Annual Reports Medicinal Chemistry Volume 1

LIST OF CONTRIBUTORS . ..............289 . .................205 . ................... 12 . ................236 . ...

Author: By C.K. Cain

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LIST OF CONTRIBUTORS

. ..............289 . .................205 . ................... 12 . ................236 . ............... 99 . ................. 99 . .................247 . ................... 30 . ............... 1 . ................. 67 . .................213 ...................247 . ...............136 . .................331 . ..................109 . ..................324 . ................. 40 . .........129 ...................331 . .................331

Anderson. G W Babock. J C Biel. J H Bloom. B M Bolhofer. W A Brodie. D A Buyske. D A Cain. C K Childress. S J Cragoe. E J Diassi. P A Dvornik. D Elslager. E F Finger. K F Flynn. E H Foye. W 0 Harris. L S Herrmann. E C., Jr Higuchi. T Higuchi. W I

. .................... 150 ..................... 277 . ...............191 ............... 78 . ................ 59 . .. .................. 129 ..................213 . ............... 92 ..................... 164 . .................... 51 . ................299 . ................ 224 . ................118 . ............... 314 . ................... 267 . ................. 67 . ................... 85 . ..................311 . ................178 .................... 233

off, D R Horita. A Jorgensen. E C Kennedy. P., Jr Kornfeld. E C Kucera L S Lerner. L J Moreland. W T Pinson. R Poos. G I Schaeffer. H J Scherrer. R A Shepherd. R G Smissman. E E Smith. C G Sprague. J M Tam. R D Taylor. W I Ursprung. J 3 Weiner. M

ANNUAL REPORTS IN MEDICINAL CHEMISTRY, 1965 Sponsored by the Division of Medicinal Chemistry of tbe American Chemical Society Editor-in-Chief: CORNELIUS K, CAIN McNElL LABORATORIES, INC. FORT WASHINGTON, PENNSYLVANIA

SECTION EDITORS JOHN BlEL 0 SYDNEY ARCHER 0 EDWlN FLYNN RICHARD HEINZELMAN 0 IRVING TABACHNICK 0 EDWARD SMISSMAN

@

ACADEMIC PRESS

New York and London 1966

B Y ACADEMIC PRESSI NC. ALL RIGHTS RESERVED. NO PART OF THIS BOOK MAY BE REPRODUCED I N A N Y FORM, BY PHOTOSTAT, MICROFILM, OR ANY OTHER MEANS, WITHOUT WRITTEN PERMISSION FROM THE PUBLISHERS.

COPYRIGHT 0 1966,

ACADEMIC PRESS INC. 111 Fifth Avenue, New

York, New York 10003

United Kingdom Edition fiublished by ACADEMIC PRESS INC. (LONDON) LTD. Berkeley Square House, London W:1

LIBRARY OF

CONGkESS CATALOG CARD

NUMBER: 66-26843

PRINTED I N T H E UNITED STATES OF AMERICA

Preface While excellent reviews in depth covering selected fields of medicinal chemistry a r e available, no publication outlines the c u r r e n t developments and trends in the whole a r e a . The p r e s e n t volume is the f i r s t of a planned annual publication in which m o r e than thirty authors p r e s e n t a c r i t i c a l summary of new and significant contributions appearing in the l i t e r a t u r e of the p a s t year concerning various fields of medicinal chemistry. Its main purpose is to enable r e a d e r s to "catch up" in fields of t h e i r p e r i pheral i n t e r e s t s and, perhaps, to find some different views in fields of their major i n t e r e s t s . The breadth of the subject and limitations of space presented to the authors a very difficult task of selection of m a t e r i a l and condensation of discussion. Recent reviews and leading r e f e r e n c e s a r e cited to guide r e a d e r s to further information if desired. Topics were chosen to achieve reasonable coverage, but a few chapters initially listed had to be postponed to future volumes. Organization of the m a t e r i a l is p r i m a r i l y by pharmacological action, although some chapter titles r e p r e s e n t concepts, chemical c l a s s e s , methods, etc. The manner of presentation v a r i e s , a s is to be expected from the various disciplines of the authors, the nature of the subjects and the lack of a previous volume to s e r v e a s a model.

1 know of no adequate way to e x p r e s s my thanks for the cheerful, enthusiastic and dedicated efforts of a l l who were involved in this undertaking. Especially to be mentioned a r e the section editors and the chapter authors, but s e c r e t a r i e s , proof-readers, a s s i s t a n t s and a l l who supplied m o r a l support and encouragement should not be forgotten. Comments, c r i t i c i s m s , suggestions and, hopefully, p r a i s e will be welcomed by authors and editors.

F o r t Washington, P a . June, 1966

Cornelius K . Cain

V

Section I - CNS Agents Editor: John H. Biel, Aldrich Chemical Co., Milwaukee, Wisconsin Chapter 1. Antipsychotic and Anti-anxiety Agents Scott J. Childress, Wyeth Laboratories, Inc., Radnor, Pennsylvania Most basic biological work concerned with CNS agents that was reported in 1965 falls into the biochemical area. The belief that the antipsychotic drugs function through some interference with adrenergic processes in the brain is widely accepted. Reserpine, for example, is known to deplete the brain of its stores of catecholamines whereas chlorpromazine has a central adrenolytic action. Although the antipsychotic agents can be shown to interfere with the brain amines, the causal relationship between the changes and the behavioral effects is less clear. The mode of action of the anti-anxiety drugs remains unknown.

A symposium on catecholamines held in Milan in 1965 and recently published1 does much to clarify present views of their role in the central nervous system. Other reviews on the biochemical effects of drugs acting on the central nervous system and on the pharmacology of the central nervous system were prepared by Decsi2 and by Bradley.3 More detailed reviews on serotonin4 and y -aminobutyric acid5 appeared. These papers provide excellent background for any fundamental consideration of the CNS drugs. If the brain amines are conceded to play a crucial part in the functioning of the central nervous system, some disorder in the supply, action or disposal of these agents might be responsible for abnormal behavior. ~ellhorn6,for example, has hypothesized that a disturbance in the noradrenalindadrenaline ratio forms a neurophysiological basis for fear and anxiety. The suggestion that toxic substances in the brain might be responsible for schizophrenia is an old one and the search for a faulty metabolic process in schizophrenics has remained a popular pursuit. Bourdillon7 has recently reEmphasized the finding of a "pink spot," probably 3 4-dimethoxyphenethylamine, in the urine of schizophrenics. Work by Ernsd supports the possibility of an abnormal metabolism of dopamine to 3,4-dimethoxyphenethylamine in schizophrenia. He studied the structure-activity relationships of a group of methoxylated phenethylamines in the production of catatonia in cats. He found the presence of a E-methoxy group and the absence of m-hydroxy group to be required with the duration of action determined by the number of methoxy groups in the molecule. Prior treatment with iprpniazid eliminated the requirement for the absence of a m-hydroxy group. The blocking of the aminooxidase resulted in g-methylation by 0-methyltransferase. A behavioral study' of this compound in the dog and cat also indicates some relationship to schizophrenia. Woolley and Gommi'' have detected in the blood of schizophrenics a substance that is synergistic with serotonin in its action on the rat uterus and are studying the possibility of a causal relationship to the mental disorder. An excellent review" on biochemistry and mental function has been published by Kety who has also republished his 1959 review12 criticizing some

2

Sect. 1 - CNS Agents

B i e l , Ed.

of the methodology involved in finding the "needle-in-the-haystack"that might explain the causes of schizophrenia. Six rejoinders from other scientists are included. Most of the compounds cited below were tested by two general methods: 1) the study of animal behavior following drug treatment in experimental models designed to mimic a clinical situation (conflict, avoidance, etc.) and 2) the measurement of classical pharmacological reactions caused or modified by the agent under test (anticonvulsant, antiemetic, etc.). These methods have been collected in a recent Hahnemann symposium volume.13 The testing of the antipsychotic compounds has been reviewed by Janssen, e t &.,I4 who rely strongly upon the production of catalepsy and the antagonism of the emetic effect of apomorphine for predicting the clinical response. In fresh work on test methods, Marriott and Spencer15 have observed that the anti-anxiety agents increase exploratory behavior in inexperienced rats whereas the antipsychotic compounds reduce such activity. The use of a treadmill in approach and avoidance studies of anti-anxiety compounds has been described by Gluckman.16 A criticism of some of the behavioral tests used for evaluating anxiety in animals has been made by Ray.17 The electronencephalographic effects of the psychotropic agents have been reviewed. 18 Methods of clinical study of psychotropic drugs have also been discussed and criticized.l9,zo Phenothiazines and Analogs - Chemical work directed toward modification of the phenothiazine drugs is presently characterized by the preparation of novel tricyclic systems to which the common basic side chains can be attached. Variation of the central ring is most frequent but the peripheral rings are attracting some attention. A group of compounds having a seven-membered central ring has been described by Stille, et a1.21,22 The synthesis of the intermediate lactams was accomplished by ring closure of the appropriate isocyanates.23 The most active of these compounds is the oxazepine (I) which is approximately equipotent with haloperidol in cataleptic and antiapomorphine effects. In a more extensive study of the thiazepine analog (11, clothiapine) an intense antiserotonin effect was measured in the paw-edema test, thus differentiating it from chlorpromazine. It is noteworthy that opening of the piperazine ring as in compound I11 practically eliminates activity.

The Czech group led by Protiva prepared a host of compounds containing seven-membered rings. Two of these having good central depressant effects are IV (octoclothepine) and V.24 Compound IV which has antiserotonin and antihistamine activities as well, is about three times as strong in its central depressant effects as its unchlorinated analog. The compounds were prepared conventionally from the corresponding dibenzothiepinone which, in turn, resulted from ring closure of the requisite 2-phenylthiophenylacetic acid.25 Reports ha e been made on several thioxanthene derivatives: VI (thiothixene), 2& 27 VII (SKF 10812), 28, 29 and VIII (N-7009). 3' Each was indicated to be effective in the treatment of psychotic states. 6iothixene was said to cause only a low incidence of extrapyramidal symptoms.

Chap. 1

Antip sychotic s, Anti -Anxiety Agents

Childres s

3 -

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v

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Sect. 1 ’

- CNS Agents

Propericiazine (IX)3 1 has been tried in psychopathic patients severe behavioral disorders with fair success and dixyrazine (X)32 found effective in anxiety associated with autonomic disturbances. ~1,33available in Europe, is a homolog of fluphenazine. Although catalepsy it does not have antiemetic properties.

B ’ i e l , .Ed. having has been Compound it produces

Neuroleptic activity has been reported for X d 4 which has a novel ring system. A metabolite of thioridazine has been identified as XIlIand shown to have a much lower neuroleptic potency than its parent.35 Since there was some suggestion of activating properties (suppression of the tetrabenazine syndrome in rabbits, potentiation of serotonin fever and central anticholinergic it was tested clinically as antidepressant agent with negative ~~~~~~~~6 However the activity in schizophrenia seems to be good.

In the continuing study of the metabolism of chlorprmazine, 2-chlorophenothiazine and 2-chlorophenothiazine 5-oxide have now been identified in human urine.37 Butyrophenones - None of the fluorobutyrophenone compounds is at present in use in the United States although they are extensively used in Europe. The recent review by Haase and Janssen is a useful summary of these comp0unds.3~ A n extension from thekr use in ps chiatry to use in surgical procedures for producinf analgesia is underway.3 j40 The appearance of several .clinical studies4 on the psychiatric use of trifluperidol indicates the prospect of its future availability for treatment of schizophrenia. There are some reports of its especial value in paranoid schizophrenia.42

B

Pharmacological and clinical data on compound XI$3 show it to resemble haloperidol except for the addition of an antireserpine effect. A homolog of XIV (XV)44 has also been studied but was found to have troublesome sideeffects. Both of these products are somewhat related to mI45 which, although having an effective antipsychotic action, caused cataracts and disturbances of cholesterol balance. A group of fluorobutyrophenones derived from 4-aminopiperidines has been described.46 The treatment of l-benzyl-4-~-aminopiperidine-4-nitriles with Grignard reagents effected displacement of the cyano group whereas organolithium reagents reacted with the cyano function to afford ketones. Subsequent debenzylation and alkylation gave the corresponding fluorobutyrophenones. These compounds are less active than haloperidol in apomorphine antagonism but are more potent in countering morphine-induced mania in cats. The most potent of these preparations is XVII. A strong neuroleptic of long duration related to the butyrophenones has recently been reported.47 Compound X a I I antagonizes the effect of apomorphine for as long as 100 hours.

Chap. 1

Antipsychotics, Anti -Anxiety Agents

-5

Child re s s

XVIII

Carbamates - A new carbamate, tybamate (XIX)48 closely resembling meprobamate in structure and in activity was marketed during 1965. Its potency is comparable to meprobamate in many tests, yet it has only one-third the potency of meprobamate in the antipentylenetetrazole test. However, in contrast to meprobamate, it antagonises the effect of LSD on the electroencephalogram and has an antiserotonin action. Convulsions are not seen in dogs receiving tybamate upon abrupt withdrawal of the drug, whereas convulsions do result upon withdrawal of meprobamate.49 In the dog tybamate is metabolized by hydroxylation and/or N-dealkylation.50 Hydroxytybamate is the principal metabolite found in the urine. Several clinical studies have appeared demonstrating effectiveness against anxiety. 51,52 One report53 suggested mild stimulant properties, but in a study with alcoholics no separation from placebo could be made.54 A series of meprobamate analogs was prepared containing silicon in place of the quaternary carbon atom.55 Each silicon compound is approximately

equivalent to its carbon analog in the rotarod test and in acute toxicity. monothiol analog (rOr) of meprobamate is also comparable to meprobamate in potency and toxicity.56

A

A chemical review of the carbamates has been written by Adams and Baron57 with some attention to biological activity.


Biel, Ed.

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Benzodiazepines - The introduction of oxazepam in 1965 brought to three the number of 1,4-benzodiazepines comycially available in the United States. ~ particularly the anticonvulsant The animal studies of oxazepam (XXI)' 3 5 8 59 and conflict tests, suggested its use as an anti-anxiety agent and clinical studies60r61 indicated its efficacy for this purpose. Its potency appears to lie between chlordiazepoxide and diazepam. The compound has also been examined as a water-soluble hemisuccinate ester, sodium salt.& In the form of its glucuronide, oxazepam is the principal excretion product in the dog and man of diazep which is also hydroxylated to some extent without N-demethylation. In the circulating serum, the most prominent metabolite of diazepam is the unhydroxylated compound XXIII. There is an indication of the presence of further phenolic metabolites whose precise structures are unknown. The metabolism of chlordiazepoxide in the dog and man results principally in the production of 7-chloro-1,3-dihydro-5-phenyl2g-1,4-benzodiazepin-2-one 4-oxide, but in the rat basic compounds as yet unidentified are produced.65 Some opening of the lactam ring was observed, but no alteration of the aromatic rings or reduction of the N-oxide function was detected. Nitrazepam (XXIV)66,67 has been introduced in Europe and is being promoted as a hypnotic but its activity profile suggests it woul be cffective against anxiety. A clinical report on a related compound (XXV)g8 indicates a resemblance to diazepam. Some additions to the list of benzodiazepinones having functional substituents have been made. French workers succeeded in preparing 3-carboalkoxybenzodiazepinones, e.g. XXVI, 69 by transimidation of the appropriate 2aminobenzophenone imines with a-aminomalonic esters followed by cyclization. The benzodiazepine esters so obtained were converted to amides and also hydrolyzed to salts of the corresponding carboxylic acids. The ease of decarboxylation upon acidification of these salts suggests that the decarboxylation products may be responsible for the high biological activity. Although the esters and amides have typical benzodiazepine profiles they are not so potent as the carboxylic acid salts which compare favorably with diazepam.

Chap. 1

Antipsychotic s, Anti -Anxiety Agents

R

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Child re s s

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Biel, Ed.

3-Acetamidobenzodiazepines were prepared by cyclization of 2-(2-acetamido2-aminoa~etamido)benzophenones.7~ A novel elimination of acetic acid from the appropriate 2-(N-acetoxyacetamid0)acetamidobenzophenone afforded the intermediate. It was possible to hydrolyze the acetamidobenzodiazepines to the corresponding 3-amino compounds and convert these products into 3-hydroxy compounds by treatment with nitrou acid. The amino and acetamido compounds are merely reported to be active.7

Stempel, et a1.,72 achieved a direct synthesis of a 3-chlorobenzodiazepinone 4-oxide by base treatment of 6-chloro-~-dichloromethyl-4-phenylquinazoline 3-oxide. The course of this ring enlargement, which was responsible for the original discovery of chlordiazepoxide, was clarified by the isolation of an intermediate, ~-dichloroacetamido-5-chlorobenzophenone oxime (ant), which slowly cyclized. Cyclization of the monochloroacetyl analog is too fast to permit its isolation. The 3-chloro substituent of the benzodiazepine product reacted conventionally with nucleophiles following removal of the N-oxide function. A number of benzodiazepinones with functional substituents in the 1position has been published along with test data.73 The general structureactivity requirements already described for the benzodiazepines obtain for the 1-aminoalkyl types. The importance of an 2-fluoro substituent on the 5phenyl ring in increasing the potency of the compounds is clear. Compound XXVII is one of the most potent of the group, but it is slightly less potent than diazepam. The activity of the related 1-aminobenzodiazepinesprepared by use of chloramine was not given.74

Compounds containing a fused naphthalene ring (XXVIII)75 and a fused pyridine ring (xxIX)76 have been disclosed. The former types are inactive and the latter are less active than diazepam. Further examples of compounds related to active benzodiazepines, but for which test data are missing, include XXXR , xw[I,78 XXXII79 and XXXIII.80 Miscellaneous Compounds - Investigations on several compounds that do not fall into the above groups were reported. The pharmacology of trimetozine (XXXIV)81 indicates it to be a tranquillizer without hypnotic or anticonvulsant properties. Compound XXXV82 has sedative properties approximating chlorpromazine but does not produce catalepsy and ataxia. A disruptive effect on conditioned behavior at very low dosage is seen with the adrenolytic compound XXXVr.83 Compound XXXVII84 is less effective than meprobamate against anxiety and it has been shown that poor absorption is not the explanation.85 The tranquillizing potency of XXXVII186 is approximately equivalent to meprobamate. Taborsky, et al.,87 have studied the effect of 1-methylation on a group of psychoactive indoles. In general, the effects on behavior of the methylated and unmethylated pairs are similar. Compound XXXIX, 88 which resembles tetrabenazine in structure, has both stimulant and depressant properties. It blocks conditioned avoidance in rats but the required dose is at least five times that of chlorpromazine. Replacement of the 2-chlorophenyl groups by an alkyl or aralkyl group leads to inactive products. A good clinical response in schizophrenics has been noted. A group of 17-haloyohimbanes89 was examined by observation of the effects on

A n t i p s y c h oti c s , A n t i - A n x i e t y A g e n t s

Chap. 1

Childress

-9

t h e behavior of untamed r h e s u s monkeys. Although 17-CT-bromoyohimbane i s approximately a s p o t e n t a s r e s e r p i n e i n a l t e r i n g behavior i t has u n d e s i r a b l e cardiovascular properties.

XXXVIII

C H -2-Cl 6 4

XXXIX References

1. 2.

3. 4. 5.

6.

7. 8. 9.

10. 11. 12.

13. 14. 15.

16.

G. H. Acheson,

Ed., "Second Symposium on Catecholamines, ' I Pharmacol. 1, P t . 1 (1966). L. Decsi i n E. Jucker, Ed., Progress i n Drug Research, Vol. 8, Birkhauser Verlag, Basel, 1965, p. 53. P.B. Bradley, Ed., "Pharmacology of t h e C e n t r a l Nervous System," Brit. Med. Bull., NO. 1 (1965). s. M r a t t i n i and L. V a l z e l l i , "Serotonin", E l s e v i e r , New York, 1965, p. 199. D.R. C u r t i s and J . C . Watkins, Pharmacol. Rev., E. Gellhorn, P e r s p e c t i v e s Biol. Med., 8, 488 (1 R . E . Bourdillon, C.A. Clarke, A.P. RiGes, P.M. Sheppard, P. Harper and S.A. L e s l i e , Nature, 208 453 (1965). A.M. Ernst, Psychopharmacologia, 383, 391 (1965). Arch. I n t e r n . Pharmacodyn., 12, M.L. Brown, W.J.. Lang and S. 439 (1965). D.W. Woolley and B.W. Gomi, Science, 1 % 670 (1965). S.S. Kety, Nature, 208, 1252 (1965). S.S. Kety, I n t e r n . r P s y c h i a t . , 409 (1965). J . H . Nodine and P.E. S i e g l e r , Eds., "Pharmacologic Techniques i n Drug Evaluation, I' Year Book Medical P u b l i s h e r s , Chicago, 1964. P.A. J. Janssen, C. J . E . Niemegeers, and K.H.L. Schellekens, A r z n e i m i t t e l Forsch., hc' 1 5 104, 1196 (1965); l& 339 (1966). A.S. M a r r i o t t and P.S.J. Spencer, B r i t . J. Pharmacol., 25 432 (1965). wd M . I . Gluckman, Current Therap. Res., 7, 721 (1965).

&., 2, No.

2,

-'

A,

cu,

S e c t . 1 - CNS Agents

10 -

B i e l , Ed.

17. O.S. Ray, Arch. I n t e r n . Pharmacodyn., 1 3 , 49 (1965). 18. 19. 20. 21. 22.

2324. 25. 26. 27. 28. 29. 30.

31.

32-

33-

34. 35.

36. 37. 38

-

39 * 40. 41. 42. 43. 44. 45. 46. 4748. 49. 50.

224 (1965). H.F. Mtfller and A.K. Mtfller, I n t e r n . J. Neuropsychiatry, L.E. H o l l i s t e r and J . E . Overall, J . New Drugs, 286 (1965). M. Ostow, J. New Drugs, 5, 3 (1965). G. S t i l l e , H. Lauener, ET Eichenberger, F. Hunziker and J. Schmutz, 841 (1965). Arzneimittel-Forsch, G. S t i l l e . H. Ackermann, E. Eichenberger and H. Lauener, I n t e r n . J. Neuropharkacol., $, 375- (1965). J. Schmutz, F. K k z l e , F. Hunziker and A . Bcrki, Helv. Chim. Acta, _336 (1965)-. J . O . J i l e k . V. Seidlova, E. Svatek, M. F'rotiva, J. Pomykacek and Z. Sedivy, Mohatsh., 96, 182 (1965). M. P r o t i v a , J.O. J;\iek, J. Metysova, V. Seidlova, I. Jirkovsky, J. Metys, E. Adlerova, I. Ernest, K. Pelz and J. Pomykacek, Farmaco, Ed. Sci., 721 (1965). A.A. Sugerman, H. S t o l b e r g and J. Herrmann, Current Therap. Res., 7, N 310 (1965). G.M. Simpson and J. Iqbal, Current Therap. Res., 7, 697 (1965). D.M. Gallant, M.P. Bishop and W. Shelton, C u r r e n t y h e r a p . Res., 7, h 415 (1965). A.A. Sugerman and F.J. L i c h t i g f e l d , Current Therap. Res., 7, 707 (1965). Y B. Holst, Acta Psychiat. Scand., 40, 415 (1965). D. Turns, H. C. B. Denber and D.N. T e l l e r , J. New Drugs, 5, 90 (1965). T . Fokstuen, I n t e r n . J. Neuropsychiatrp, 1, 294 (1965).* T.M. Itil, Arzneirnittel-Forsch, 2, 817 (y965). Sandoz, Neth. Pat. 6,507,469 (1965). D.M. G a l l a n t , M.P. Bishop and D. Sprehe, Current Therap. R e s . , 7, v 102 (1965). D.M. Gallant, M.P. Bishop and C. S t e e l e , Current Therap. k., 7, N 783 (1965). D . E . Johnson, C.F. Rodriguez and H. P. Burchf i e l d , Biochem. Pharmacol., cvv' 14 1453 (1965). H.J. Haase and P.A.J. Janssen, Eds., "The Action of Neuroleptic Drugs," Year Book Medical Publishers, Chicago, 1965. L. T o r e l l i and F. Schiavi, Aggressologie, 6, 327 (1965). N.W. Shephard, "The A p p l i c a t i o n of Neuro1e;tanalgesia i n Anesthetic and Other P r a c t i c e , Pergamon Press, Oxford, 1965. A.A. Sugerman and B.H. W i l l i a m s , J. New Drugs, 5 318 (1965). L . E . H o l l i s t e r , J . E . Overall, J . L . Bennett, I. 4 K m b e l l , Jr. and J. Shelton, Am. J. Psvchiat., 13, 9 6 (1965). J . A . Christensen, S. Hernestam, J . B . Lassen and N. S t e r n e r , Acts Pharmacol. Toxicol., 23 109 (1965). -' G.M. Simpson, E. Kunz and T.P.S. Watts, Psychopharmacologia, 5 223 (1965). G.M. Simpson, T . Farkas and J . C. Saunders, Psychopharmacologia, 306 ( 1 9 a ) . B. Hermans, P. Van Daele, C . Van De Westeringh, C. Van Der Eycken, J . Boey and P . A . J . Janssen, J . Med. Chem., 5 851 (1965). P.A.J. Janssen, Fr. P a t . 3695M (1965). F.M. Berger, M. Kletzkin and S. Margolin, Med. E x p t l . , fi 327 (1964). S. Margolin, O.J. Plekss and F.M. Berger, Pharmacoloqist, 143 (1965). J.F. Douglas, J. Edelson, A. Schlosser, B. J. Ludwig and F.M. Berger, Federation Proc. No. 1, P t . 1, 489 (1964).

3

9,

45,

a

3

2,

3,

Chap. 1 51. 52. 53 * 54. 55. 56. 57. 58. 59.

Antipsychotics, Anti-Anxiety Agents

11 -

Childress

M. C h i e f f i , Diseases Nervous System, 2 6 369 (1965).

I. Slaughter, J. New Drugs, 177 (lpbs). E . Raab, K. Rickels and E. Moore, Am. J. Psychiat., H.B. Mooney and K.S. Ditman, J. New Drugs, 233 (1 R . J . Fessenden and M.D. Coon, J. Med. Chem., 604 (1965). M.A Leaffer, W.A. Skinner and B . J . Ludwig, J. Med. Chem., 5 208 (1965). P. Adams and F.A. Baron, Chem. Rev., c 5 , 567 (1965). H. Klupp and J. G h l i n g , Arzneimittel-Forsch., 359 (1965). L.O. Randall, C.L. Scheckel and R.F. Banziger, Current Therap. Res., 590 (1965). €3. S c a s s e r r a , Diseases Nervous Sys tem, 2J_6, 511 (1965). 60. 61. W. Janke and K. -D. Stoll, Arzneimittel-Forsch., 15, 366 (1965). 62. S.N. Steen and L.R. Martinez, Anesthesia A n a l g e s g , Current Res., 44, 358 (1965). 63 H.W. -Ruelius, J.M. Lee and H.E. Alburn, Arch. Biochem. Biophys., 1,1-_1, 376 (1965). 64. M.A. Schwartz, B.A. Koechlin, E. Postma, S. Palmer and G. Krol, 2. Phannacol. E x p t l . Therap., lA8, 423 (1965). 65. B.A. Koechlin, M.A. Schwartz, G. Krol and W. Oberhansli, J. Pharmacol. Exptl. Therap., lk8, 399 (1965). 66. L.O. Randall, W. Schallek, C. Scheckel, R . E . Bagdon and J. Rieder, Schweiz. Med. Wochschr., %, 334 (1965). 67- W. F. Borck, Arzneimittel-Forsch., 9, 1155 (1965). 68. H.O. Gerz, Am. J. Psychiat., 121, 495 (1964). 69. Etab. Clin-Byla, Belg. P a t . 6 K 4 0 1 (1965). 70- S . C. Bell, R. J. McCaully and S . J. Childress, Tetrahedron L e t t e r s , 2889 (1965). 71- S. C. Bell, U . S . Pat. 3,198,789 (1965). 4267 (1965). 72- A. Stempel, E. Reeder and L.H. Sternbach, J. Org. Chem., 73. L. H. Sternbach, G.A. Archer, J .V. Earley, R. I. Fryer, E. Reeder, N. Wasilyw, L.O. Randall and R. Banziger, J . Med. Chem., 4, 815 (1965). 74. W. Metlesics, R.F. Tavares and L.H. Sternbach, J. Org. Chem., 30, 1311 (1965). R. L i t t e l l and D.S. Allen, Jr., J. Med. Chem., 5 892 (1965). 75 76. R. L i t t e l l and D . S . Allen, Jr., J. Med. Chem., 5 722 (1965). 77. E. T e s t a and L. Fontanella, Farmaco, Pavia, Ed. Sci., 20, 323 (1965). 78 * P. H.L. Wei, U. S . Pat. 3,185,680 (1965). 79. L.H. Sternbach, H. Lehr, E. Reeder, T . Hayes and N. S t e i g e r , J. Or&. Chem., 0 2812 (1965). icolaus, E. B e l l a s i o , G. Pagani, L. Mariani and E. Testa, 80. B . J . R . a i m . Acta., 1867 (1965). 81. J . - R . B o i s s i e r , P. Simon and J. Fichelle-Pagny, Therapie, 2 3 401 (1965). 82. H. Fujimori and D.P. Cobb, J . Pharmacol. Exptl. Therap., lA8, 151 (1965). V.G. Longo and V. Rosnati, Psychophannacologia, 145 (1965). 83 84. J. Janacek, B . C . Schiele, T.P. B e l l v i l l e , N.D. Vestre and 0. Raths, 2. New Drugs, 5 51 (1965). 85. B.M. P h i l l i p s , C. E. P i l k v i s t and P. J. Kraus, Arch. I n t e r n . Pharmacodyn., 156, 358 (1965). 704 (1965). 86. L.M. Rice and C. H. Grogan, J Med. Chem., 87 * R . G . Taborsky, P. Delvigs, I . H . Page and N. Crawford, J. Med. Chem., fL 460 (1965). 88. C.R. Ganellin and R.G.W. S p i c k e t t , J. Med. Chem., 619 (1965). 89. M. von Strandtmann, G. Bobowski and J. Shavel, Jr., J. Med. Chem., 338 (1965).

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Sect. I

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Biel, Ed.

f

Chapter 2. Antidepressants, Stimulants, Hallucino ens J. H. Biel, Aldrich Chemical Company, Milwaukee, W 8 .

I.

The Antidepressants A. Introduction There were no spectacular break-throughs in the treatment of mental depression durin 1965. However, the development of drugs that displayed a select ve type of antidepressant activity underscored the very complexity of mental depressive illness and afforded a greater understanding of the fact that mental depression is not a single disease entity but requires individualized therapy and the availability of drugs capable of coping with the various facets of this mosaic disease syndrome. Other major developments demonstrated the influence of the antidepressant drugs on catecholamine metabolism, uptake, storage, and intracellular binding. These findings shed new light on the mechanism of action of these drugs pointing to a possible etiology of a breakdown in central chemical homeostasis. Well-controlled clinical investigations brou ht into sharper focus the need for both stimulant and tranquiliz ng antidepressant agents, particularly where depressant symptoms were an overt expression of an underlying psychotic illness which wa exacerbated by the "stimulantT1 type of antidepressant. introduction of monodemethylated imipramine and amitriptyline derivatives was a ste in the direction of achieving greater selectivity of action.g,4,5,6 B. The MA0 Inhibitors 1. New Structures

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CH3 I $CH2CH(CH3 )N-CH2CECH

ArC O( C H 2)

(IV)

( IVa)

R;R .R -lower '-alkyl groups (VI)

p a H

N-C OR #-R

(V) Ar = phenyl or substituted phenyl R = alkyl, cycloalkyl, heterocyclic amfne

Chap. 2

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Structures I and I1 are modifications of pargyline (Eutonylm). Knoll et a1.8 d e s c r i b e s t r u c t u r e I1 as being ?'an acute psychostimulant" and ? ? achronic psychic energizer". I t s MA0 i n h i b i t o r y potency i n v i t r o i s s a i d t o be 200 times t h a t of NiamidTM. Unlike pargynn-is agent is a potent c e n t r a l stimulant comparable t o amphetamine i n potency. S t r u c t u r e 111, a phenoxy analog of tranylcypromine w a s o et h i r d a s potent a s the l a t t e r drug and twice a s long-lasting?*g I n r a t s , I11 displayed moderate anorexigenic and increased locomotor a c t i v i t i e s . As an MA0 i n h i b i t o r , compound I V was approximately onehundredth as potent a s pheniprazine (a-methylphenethylhydrazine). As a group, these compounds displayed a v a r i e t y of pharmacologic e f f e c t s : CNS stimulation, tryptamine and nfEotine antagonism The d a t a presented and suppression o f f i g h t i n g mouse behavitvr. do not allow a conclusion concerning t h e i r p o t e n t i a l a s a "lead" i n the a r e a of antidepressants o r CNS s t i m u l a n t s . The s e r i e s is i n t e r e s t i n , however, because of t h e d u a l i s t i c type of psychot r o p i c a c t on ( e x c i t a n t and t r a n q u i l i z i n g ) and bears f u r t h e r watching. Compound V i s another s t r u c t u r e displaying a multitude of pharmacologfc a c t i o n s Both n e u r o l e p t f c and Tfpotenttti n v i t r o MA0 i n h i b i t o r y p r o p e r t i e s a r e ascribed t o t h i s s e r i e s . mec l i n i c a l u t i l i t y of t h i s s t r u c t u r a l group i n mental depression remains i n doubt. Structure i l l u s t r a t e s v a r i a t i o n s on t h e theme of Monasem (etryptam n e ) . Compound V I I has been i n v e s t i g a t e d c l i n i c a l l y by Azirnal3 who found it t o be an e f f e c t i v e a n t i d e p r e s s a n t . The 7-methyl-a-ethyltryptamine ( V I I I ) is s a i d t o be s u p e r i o r a s an MA0 i n h i b i t o r t o etryptamine, both i n v i t r o ( t e n times) and vivo ( t w o t o f o u r t i m e s ) . l 4 The c l s i c a l t i l i t y o f t h i s agent E n t i d e p r e s s a n t therapy has n o t been revealed.

f

B

(VII) MP-809 (VIII) 2 . New Developments on Older MA0 I n h i b i t o r s The hypertensive c r i s e s produced by t r a n lcypromine i n t h e presence of tyramine-rich foods 15915a9 15b, has r e s t r i c t e d the a p p l i c a t i o n of t h i s valuable agent t o h o s p i t a l use. While o t h e r MA0 i n h i b i t o r s evoke s i m i l a r responses i n tyramfnet r e a t e d r a t s , 16 the i n t r i n s i c sympathomimetic a c t i v i t i e s of tranylcypromine presumably enhance i t s potency i n t h i s regard .I7 E f f o r t s t o overcome t h e p e r i p h e r a l s i d e e f f e c t s of t h e MA0 i n h i b i t o r s have taken t w o d i r e c t i o n s : (1) Masking o f t h e f r e e amino group of tranylcypromine by a s u i t a b l e a c y l radical18, 19

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(structures I X and X I which would not impede the d r u g ' s passage

( 1x1

(XI across the blood-brain b a r r i e r nor form so s t a b l e an amide linkage as t o preclude enzymatic cleavage t o the f r e e d n e a t the t a r g e t s i t e . ( 2 ) Blockade of the e r i heral c e l l receptors of MA0 by a reversible MA0 i n h i b i t o r w t h greater receptor a f f i n i t y than the therapeutically active MA0 inhibitor and an i n a b i l i t y t o penetrate the blood-brain barrier. I n t h i s way, the therapeutic MA0 i n h i b i t o r Will be forced i n t o the c e n t r a l nervous system r metabolized t o an e a s i l y excretable metabolite. HoritaS8 has succeeded i n demonstrating the u t i l i t y of t h i s concept. Wemedication of the r a t with a reversible MA0 i n h i b i t o r , BW 392C60 ( X I ) , followed by treatment with pheniprazine blocked brain MA0 completely, but maintained h i h MA0 a c t i v i t y i n the l i v e r and other peripheral organs. Phen prazine and pargyline could be e f f e c t i v e l y antagonized, but n o t tranylcypromine o r iproniazid. Compound MO 1255 ( X I 1 1 has been claimed t o be an acgfve antidepressant devoid of cardiovascular side effects. NCH3

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f

O-CI~~H~NH!!-NHCH~

( X I ) BW 392C60 ( X I I ) MO 1255 (encyprate) neTM (2-piperidino-3-methylpyrazine) has been shown by Rider t o produce g a s t r i c antisecretory e f f e c t s comparable t o atropine. The drug has properties common t o both MA0 inhibit o r s and the imipramine-type agents. A s an MA0 inhibitor, it is f o u r t o s i x t b e s as potent as phenelzine, but unlike the l a t t e r , produces r a t h e r severe o r t h o s t a t i c hypotension i n man.22a 3. Mechanism of Antidepressant Action of MA0 Inhibitors A t the present s t a t e of our knowledge, the mechanism of the antidepressant action of the MA0 i n h i b i t o r s i s thou h t t o be intimately t i e d t o brain catecholamine levels. Sch ldkraut 23 has summarized the evidence favoring the involvement of catecholamine In transmitting the e f f e c t s of the MA0 inhibitors. Spector 28 showed t h a t during selective depletion of norepinephrine and dopamine, the MA0 inhibitor, pargyline, was unable t o reverse reserpine o r tetrabenazine depression u n t i l brain catecholamine levels had stached 50% of pre-dru levels. Recently, Ingvarsson has reported dramat c remissions of long-standing drug r e s i s t a n t depressions following the administ r a t i o n of 50 mg. of DOPA every other day. Marked improvement

a

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was seen within a few hours. P a t i e n t s a l s o a f f l i c t e d with asthma and Parkinsonism experienced complete r e l i e f of t h e i r symptoms from the DOPA treatment. Relapse occurred on discontinuance of DOPA therapy. The i n h i b i t i o n of NE biosynthesis by blocking t h e r a t e l i m i t i n g s t e p with a-methyltyrosine r e s u l t e d i airment of motor a c t i v € t y and s e d a t i o n i n animals and man Clinical improvement i n t h e depres9Bd a t i e n t c o r r e l a t e d w e l l with t h e degree of MA0 i n h i b i t i o n . 9 28 Recently, Pletscher30 has presented evidence t h a t the MA0 i n h i b i t o r s may block the uptake of r e l e a s e d NE i n t o s t o r a g e granules, thereby producing an increased concentration of NE around t h e adrenergic synapses. 4. Conclusions a. P o t e n t , i r r e v e r s i b l e i n h i b i t i o n of b r a i n MA0 i s a primary p r e - r e q u i s i t e f o r e f f e c t i v e a n t i d e p r e s s a n t therapy. b. The c l o s e temporal r e l a t i o n s h i p between t h e onset of MA0 i n h i b i t i o n and a n t i d e p r e s s a n t e f f e c t s lends f u r t h e r support t o t h e hypothesis t h a t "free" NE, p r o t e c t e d from o x i d a t i v e metabolism, may be implicated i n mediating t h e a n t i depressant e f f e c t s of the MA0 i n h i b i t o r s . c. C l i n i c a l l y , t h e MA0 i n h i b i t o r s e x e r t optimum a n t i d e p r e s s a n t e f f e c t s i n r e a c t i v e and n e u r o t i c depressions. Activated, psychotic o r endogenous depressions were l e s s s u s c e p t i b l e t o MA0 i n h i b i t o r y therapy.25731 d. The "False Neurochemical Transmitter" theory promulgated by Kopin e t a1.32 t o e x p l a i n t h e sympathetic blocking p r o p e r t i e s of t h e MA0 i n h i b i t o r s , must be s e r i o u s l y considered a l s o w i t h r e s p e c t t o the c e n t r a l p r o p e r t i e s of t h e s e agents. I n essence, t h i s hypothesis proposes t h a t MA0 i n h i b i t i o n w i l l produce an accumulation of sympathomimetic m e t a b o l i t e s which a r e normally n o t present i n t h e body, but have s u f f i c i e n t a f f i n i t y f o r t h e adrenergic r e c e p t o r s i t e s t o d i s p l a c e the r e g u l a r l y p r e s e n t n e u r o t r a n s m i t t e r s (e.g., norepinephrine, dopamine) from sympathetic nerve endings. Furthermore, sympathetic nerve s t i m u l a t i o n w i l l r e l e a s e these agents i n t h e same manner a s it does NE; however, the r e s u l t a n t e f f e c t w i l l be g r e a t l y d i l u t e d , since t h e f a l s e n e u r o t r a n s m i t t e r s have d i s t i n c t l y weaker adrenergic p r o p e r t i e s than NE o r dopamine. Normally, tyramfne is r a p i d l y metabolized by MA0 so t h a t l i t t l e , i f any, octopamine is formed. I n t h e presence of MA0 i n h i b i t o r s , however, s i g n i f i c a n t amounts of octopamine a r e produced.

Ss:B -

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D 2H4NH2

(XIII) Tyramine

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(XIV) Octo m i n e 0-1

transmitter

5. Review A r t i c l e s t a i l e d information regarding ad For f u r t h s i d e e f f e c t s , 45, comparative c l i n i c a l e f f i c a c y Y$:J!,

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al sb,iysc and

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B i e l , Ed.

p o s s i b l e mechanism of a c t i o n 3 8 7 3 9 9 4 0 of t h e MA0 i n h i b i t o r s , t h e r e a d e r i s r e f e r r e d t o the c i t e d review a r t i c l e s . S t r u c t u r e- ac t i v i t y , biochemical , pharmacological and c 1i n i c a l pharmacological d a t a on both hydrazine 39, 40 and non-hydrazine MA0 i n h i b i t o r s 41 have been covered extensively i n the respect i v e references. S c h i l d k r a u t ' s paper 38 i s of s p e c i a l i n t e r e s t , s i n c e it provides much of t h e supporting evidence f o r the "Catecholamine Theory" of the antidepressant drug a c t i o n . C. The Thymoleptic Agents ( T r i c y c l i c Antidepressant Drugs) 1. Introduction Listed below a r e t h e s t r u c t u r e s of the t r i c y c l i c antidepress a n t s which a r e e i t h e r commercially a v a i l a b l e o r In advanced

(XV)

I m i ramine

R=CH3: R=H :

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(XVI) R=CH3: Amitriptgline R=H : Nortrm

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(XVIII) (XIXI Trimipramine Opipramol Kuhn's discovery42 of t h e antidepressant e f f e c t s of imipramine c o n s t i t u t e d a major break-through i n t h e treatment of mental depression. A e x c e l l e n t and comprehensive review by H'etfliger and BurckhardtQ3 covers t h e chemistry, pharmacology, and c l i n i c a l e f f e c t s of t h i s drug group u n t i l 1963. 2. Evidence f o r Enhancement of Adrenergic Responses by t h e Thymoleptic Drugs The o r i g i n a l pharmacolo i c spectrum of imipramine ave no h i n t of i t s p o t e n t i a l a c t i v t y a s a novel c l i n i c a l a n t depressant; rath the drug behaved l i k e a mild t r a n q u i l i z e r i n animals. S i gEg7w a s t h e f i r s t t o d i s c e r n pharmacologic d i f f e r e n c e s between i m pramine and chlorpromazine on t h e b a s i s of enhancement of c e r t a i n adrenergic responses t o exogenously administered NE by t h e former drug. Sigg ascribed t h i s a c t i o n of the drug t o a I * s e n s i t i z a t i o n of EQe adrenergic r e c e p t o r s Kaumann e t a l . demonstrated an increase i n c a r d i a c r a t e and f o r c e of c o n t r a c t i o n w i t h desipramine which would be blocked by D C I . U r s i l l o and Jacobsen46 working with the i s o l a t e d

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Chap. 2

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Biel

v a s deferens achieved marked q u a n t i t a t i v e d i f f e r e n c e s between m x o r and major a n t i d e p r e s s a n t s . Thus, desipramine had 50 100 times t h e potency of methylphenidate. Amitriptyline, chlorprothixene, chlorpromazine produced only i n h i b i t i o n of NE i n t h i s t e s t . Catecholami -induced h erthermia i n r a t s was p o t e n t i a t e d by imipramine.gq Imipram+a-n ne an e s pramhe, i n small doses, enhanced amphetamine stimulant and hyperthermic e f f e c t s . Opipramol produced only a s l i g h t p o t e n t i a t i o n and c l i n i c a l l y , t h i s drug i s l e s s of an a n t i d e p r e s s a n t than an a n x i o l y t i c agent. 3 . Mechanism of NE P o t e n t i a t i o n by t h e Thymoleptic Agents One of t h e major r o u t e s of i n a c t i v a t i o n of f r e s h l y r e l e a s e d (from c e l l u l a r binding s i t e s ) NE i s re-uptake by t h e cell.48a Glowinski and Axelrod 49 devised a technique capable of d e t e r mining b r a i n l e v e l s of exogenously administered (by i n t r a v e n t r i c u l a r i n j e c t i o n ) t r i t i a t e d NE. The exogenous NE i s taken up and r e t a i n e d by the sympathetic nerve endings i n the brain and behaves biochemically l i k e the endogenous neurotransmitter. These i n v e s t i g a t o r s were a b l e t o show t h a t only c l i n i c a l l a c t i v e antidepressant drugs ( h i p r a m i n e , desipramine an am tr p t y m were capable of reducing t h e uptake of t r i t i a t e d NE i n t h e r a t brain. A c l o s e s t r u c t u r a l analog of imipramine, i n a c t i v e a s an antidepressant, was devoid of any a c t i v i t y on NE uptake. The authors suggest t h a t t h e a b i l i t y of c l i n i c a l l y a c t i v e antidepress a n t s t o block t h e re-uptake of f r e s h l y r e l e a s e d "free" ( a c t i v e ) NE by t h e c e r e b r a l t i s s u e s may accoun f o r t h e mechanism of t h e i r antidepressant a c t i o n . Iversent0 working with the i s o l a t e d r a t h e a r t , found desipramine t o be 100 times more potent a s an i n h i b i t o r of NE uptake than chlorpromazine. I n the i s o l a t e d perfused c a t spleen, Thoenen e t &.51 showed t h a t NE output r e s u l t i n g from sympathetic s t f m u l a a o n was increased and t h e i n a c t i v a t i o n of exogenously administered NE delayed i n t h e presence of prev ously administered imipramine o r p r o t r f p t y l i n e . Haefely e t a l . 53 concluded from t h e i r s t u d i e s w i t h t h e , a c t i v e thymoleptic drugs, t h a t such a n t i d e p r e s s a n t s exerted a t l e a s t t h r e e types of a c t i v i t y a t t h e p e r i p h e r a l adrenergfc synapses: (1) a sympathomimetic e f f e c t , presumably due t o r e l e a s e of a c t i v e NE from i t s binding s i t e s , ( 2 ) i n h i b i t i o n of re-uptake of "E by the storage s i t e s of sympathetic nerve endings, and (3) a sympathicolytic or noradrenolytic e f f e c t i n higher doses. The desmethyl d e r i v a t i v e s were uniformly more potent i n i n n s i f y i n g t h e sympathetic e f f e c t s of neuronally r e l e a s e d NE. f

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4

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I n t e r a c t i o n of Thymoleptics with Reserpine, Tctrabenazine, o r Benzoquinolizlnes The thymoleptfc agents respond s i m i l a r l y t o t h e bove t h r e e catecholamine "releasing" drugs. S u l s e r and SorokoS3 have shown t h a t the r e v e r s a l of r e s e r p i n e sedation depends on the a v a i l a b i l i t y of NE s t o r e s and t h e r a t e of r e l e a s e of NE from i t s binding 4.

18

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s i t e s . I n animals, s e l e c t i v e l y depleted of t h e i r NE by a - M , the thymoleptic drugs were unable t o r e v e r s e the r e s e r p i n e induced depression. There was a d e f i n i t e temporal r e l a t i o n s h i p between b r a i n l e v e l s of desipramine and r e v e r s a l of the s e d a t i v e response of the benzoquinolizines .54 Hence, t h e authors concluded t h a t t h e r e v e r s a l of r e s e r p i n e s t u p o r by t h e thymolept i c drugs is dependent on r a p i d and copious r e l e a s e of b r a i n catecholamines. 5. A n t i c h o l i n e r g i c E f f e c t s of Thymoleptic Drugs An a l t e r n a t e o r a d d i t i o n a l mechanism of a n t i d e p r e s s a n t drug a c t i o n which would implicate blockade of c e n t r a l cholfgergic responses had been proposed o r i g i n a l l y by B i e l et a l . as imipramine and desipramEe have been Thymoleptic drugs , shown by S u l s e r e t :??6 t o antagonize a l l t h e c e n t r a l parasympathomimetic e f f e c t s of r e s e r p i n e (increased s a l i v a t i o n , muscular r i g i d i t y , hunchback posture and blepharospasms), even i n catecholamine-depleted animals. The c e n t r a l a n t i c h o l i n e r g i c a c t i v i t y of oxygen i s o s t e r e s o g 7 a m i t r i p t y l i n e and n o r t r i p t y l i n e <xX and XXI) w a s demonstrated . by t h e i r antagonism t o t h e c h o l i n e s t e r a s e i n h i b i t o r , d i e t h y l p-nitrophenyl phosphate (Paraoxon) and emetic e f f e c t i n pigeons. Increased p e r i p h e r a l a n t i c h o l i n e r g i c e f f e c t s were displayed by t h e c e n t r a l l y more potent diastereoisomer (B) of s t r u c t u r e X X I I . Diastereofsomer (A) w a s considerabfg l e s s a c t i v e a s an a n t i c h o l i n e r g i c and c e n t r a l stimulant.

Monro e t &.” i n v e s t i g a t e d a s e r i e s of t r i c y c l i c a n t i d e p r e s s a n t a r u g s and found a p o s i t i v e c o r r e l a t i o n between potent CNS p r o p e r t i e s and a n t c h o l i n e r g i c potency i n animals. Giarman and Pepau6& demonstrated t h a t only c e n t r a l l y a c t i v e (animals and man) b a s i c g l y c o l a t e e s t e r s caused a reduction i n b r a i n a c e t y l c h o l i n e (AcCh) l e v e l s of t h e r a t . The authors suggested as a l i k e l y mechanism, i n t e r f e r e n c e of the psychotropic g l y c o l a t e s with s t o r a g e of b r a i n acetylchoF2ne r e s u l t i n g i n reduced uptake of newly synthesized AcGh. Conclusion. On t h e basis of p r e s e n t l y a v a i l a b l e experimental evidence, one would have t o conclude t h a t t h e mechanism of a c t i o n of t h e t r i c y c l i c a n t i d e p r e s s a n t drugs may be due (1) t o an i n t e r ference with c e l l u l a r binding of b r a i n catecholamines, presumably NET thereby producing increased concentrations of catecholamines a t t h e c e n t r a l adrenergic synapses, and (2) a lowering of b r a i n AcCh l e v e l s which would tend t o enhance the o v e r a l l antidepressant effect.

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D. Newer Antidepressant Drugs Two drugs which represent structural departures from the currently marketed antidepressants are shown below (XXII1,XXIV):

QcsJ

2H4NMe2

8;

(XXIV) IN 1060

Compound XXIII displayed activity only in "septat;;; rats by suppressing the rage reaction and hyperirritability. Unlike other antidepressants, XXIII did not produce a reserpine reversal. In man, prelim nary data i n E a t e it to be a rapidly acting antidepressant drug. 62 As to compound IN 1060, Sletten et ,1.62 concluded a that the pharmacologic profile of this compous resembles that of imipramine with respect to (1) activation of psychotic processes, ( 2 ) increase in spontaneous motor activity in mice, (3) reversal of reserpine-induced ptos.is and depression in rats, (4) antagoni s m to Ditran-induced behavior in dogs,and ( 5 ) potentiation of epinephrine and NE pressor response of systolic blood pressure in man. E. The Significance of Imipramfne Metabolites K ~ h has n ~ tried ~ to correlate the urinary excretion of imipramine metabolites with clinical improvement. Imipramine Metabolites

(XXVII) desipramine n

(CH ) 3-NHCH3

(XXVIII) While a strict correlation proved difficult, clinical improvement normally became evldent following the maximum urinary excretion of metabolite XXVIII which usually occurred between the sixth and fifteenth day of therapy and was preceded by accumulation of

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metabolite X X V I I , desipramine. Kuhn suggests t h a t t h e formation of metabolite XXVIII i s dependent on t h e presence of s i g n i f i c a n t q u a n t i t i e s of X X V I I whose formation may be t h e r a t e - l i m i t i n g s t e p i n generating metabolite X X V I I I . The p a r a l l e l i s m i n t h e temporal r e l a t i o n s h i p between the o n s e t of t h e a n t i d e p r e s s a n t e f f e c t following imipramine and t h e appearance of maximal amounts of XXVIII i n the u r i n e would e x p l a i n gbe more r a p i d on t of a c t i o n S u l s e r et al.3g have shown (two t o f o u r days) of desipramine. t h a t animal s p e c i e s which a r e unable t o convert s i p r a m i n e t o desipramine a r e a l s o incapable of counteracting r e s e r p i n e o r benzoquinolizine-induced s e d a t i o n w i t h imipramine. F . C l i n i c a l P r o p e r t i e s of Antidepressant Drugs A number of review papers have appeared concerning t h e c l i n i c a l pharmacologic23 1 i 1 r o e i e s of t h e MA0 i n h i b i t o r y and thymoleptic agents. and6g, gy, 68,68,% Ayd has published a compilation of h i s c l i n i c a l experiences w i t h a m i t r i p t y l i n e during a Fix-year p e r i o d . Space permits only a summary of t h e general conclusions which have been reached by t h e s e authors: 1. Mental depression i s a multifaceted d i s e a s e syndrome w i t h varying types of e t i o l o g y . I t may be primary o r secondary ( i . e . , r e s u l t i n g from o t h e r mental disturbances such a s severe a n x i e t y o r an underlying psychosis). It may be r e a c t i v e ( i . e . , i n response t o an environmental s t r e s s ) o r a r i s i n g from within the p a t i e n t due t o a I t i s o f t e n s u b j e c t t o a spontaneous remission. make-up). 2 . W i t h r e s p e c t t o t h e comparative e f f i c a c i e s of t h e a n t i d e p r e s s a n t s , t h e r e c e n t review paper by Wechsler 5 al.69 i s probably most p e r t i n e n t . The a u t h o r s ' conclusion may-6e summarized as follows: a. V a r i a b i l i t Reported e f f e c t i v e n e s s f o r h i p r a m i n e , amit-EST, i p r o n i a z i d , phenelzine, i s o c a r boxazid and nialamide o f t e n ranged from 0 t o 100%. Amitriptyline had t h e l e a s t v a r i a b i l i t y (32 t o 79%). b. Improvement Rate - Average improvement r a t e f o r p a t i e n t s on imipramine, a m i t r i p t y l i n e , and isocarboxazid was 65%, whereas the range f o r i p r o n i a z i d , phenelzine, and nialamide was 40 t o 49%. ECT ranked t h e highest w i t h 72% improvement i n depressive symptoms and placebo therapy the lowest (23%). c . R e l a t i v e Chronicity of Depression Depressions of r e c e n t o r i g i n afforded a much higher improvement r a t e than chronic depressions. For phenelzine, the r a t e decreased from 56 t o 8%, and f o r imipramine and a m i t r i p t y l i n e from 69 t o 45% and 66 t o 32%, r e s p e c t i v e l y . 3. Anergic ( l e t h a r g i c ) depressions responded best t o the "stimulanttt type of a n t i d e p r e s s a n t (imipramine, desipramine, p r o t r i p t y l i n e ) , whereas a g i t a t e d o r anxiety depressions improved most with t h e "sedativet7 type of a n t i d e p r e s s a n t drug ( a m i t r i p t y l i n e , n o r t r l p t y l i n e ) . A l l t h e a n t i d e p r e s s a n t s exacerbated psychotic symptoms; however, a m i t r i p t y l i n e , having a t h e r a p e u t i c spectrum i n between chlorpromazine and imipramine, was t h e s m a l l e s t offender i n t h i s regard. The r e c e n t combination ( T r i a v i l m , E t r a f o n m ) of a potent a n t i d e p r e s s a n t ( a m i t r i p t y l i n e )

kt,

-

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with a p o t e n t t r a n q u i l i z e r (perphenazine, T r i l a f o n m ) r e p r e s e n t s an attempt t o d e a l more e f f e c t i v e l y with d e p r e s s i o n s accompanied by a n x i e t y , a g i t a t i o n o r schizophrenic s y p t o m a t o l o g y . The p r e l i m i n a r y r e p o r t s appear f a v o r a b l e . 72, 3 ~ 7 4 4. The desmeth 1 d e r i v a t i v e s o f hi ramine (desipramine, , Norpraminm, P e r d ) and a m i t r i p t yl-iptyline A v e n t y l m ) provided a f a s t e r o n s e t of a c t i o n (two t o f o u r days) and a l e s s e n e i n t e n s i t y of parasympatholytic and a d r e n o l y t i c s i d e e f f e c t s . 9 5 , 76977 N o r t r i p t y l i n e proved t o be a valuable adjunct i n t h e treatment of g a s t r o - i n t e s t i n a l disturbances.78 G . C l i n i c a l P r o p e r t i e s of Some Newer Antidepressant Agents More r a d i c a l s t r u c t u r a l d e p a r t u r e s from t h e imipramine and a m i t r i p t g l i n e - t y p e of a n t i d e p r e s s a n t agent a r e shown below: Newer Antidepressant Structures YH2CH2N(CH3l2

(XXX) ID-22

CH3

( X X X I I I ~P-4599

(=I)

(N

HF 1927 o G r m )

(XXXII) SKF 10810

(XXXV) IN 1060

Preliminary c l i n i c a l d a t a i n d i c a t e t h a t ID-22 is a s a t i s f a c t o r y a n t i d e p r e s s a n t endowed w i t h both s t i m u l a n t and t r a n q u i l i z i n g p r o p e r t i e s (dependin on t h e p a t i e n t ) ; s i d e e f f e c t s included o r t h o s t a t i c hypote f o n , dry mouth, c o n f u s i o n a l symptoms, and nocturnal anxiety Compound HF-1927 w a s e f f e c t i v e i n t h e treatment o f i n h i b i t e d and a g i t a t e d endogenous d e p r e s s i o n s ; t h e incidence of psychotomimetic and c a r d i o v a s c u l a r s i d e e f f e c t s w a s high. 807817 82 Freeman e t al.83 have described t h e r a p i d ( t h r e e days) o n s e t of thiazesim, n t e r two weeks' t r e a t m e n t with t h i s agent, 70% of t h e p a t i e n t s could be discharged. Unfortunately, t h e d i s char e r a t e w a s q u i t e comparable i n t h e placebo-treated group. The mipramine-like p r o p e r t i e s of I N 1060 i n animals and man In preliminary c l i n i c a l have been discussed i n S e c t i o n I - D . s t u d i e s , t h e drug e x e r t e d b e n e f i c i a l e f f e c t s i n a n e r g i c schizophrenics and a s m a l l number of depressed p a t i e n t s .84

.

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H. The Anticholinergic Antidepressants The clinical psychotomimetic and Rytidepressant properties A more recent study by of Ditran have been reviewed by Biel. Davis et a1.86 found this drug a "worthwhile, safe, and effective" antidepressant when tested in 78 patients over a period of two and one half years. Improvement became apparent after fi.ve to six treatments spaced two to three days apart. Tachyphylaxis to the psychotomimetic effects were quite pronounced in all patients. Prolonged remissions of illness appeared possible. Reactive, psychotic, and schizo-affective depressions responded best to Ditran, whereas schizophrenic and psychoneurotic depressions proved quite resistant to this type of therap In a well-controlled study by Fink et a1.87 the addition of an anticho1inergic-antiparkinsonism agent, procyclidine, to chlorpromazine produced an antidepressant effect comparable to imipramine . Centrally active anticholinergic agents, either alone or in combination with a tranquilizer, de$erve further evaluation as potential antidepressant drugs. Final Conclusions The principal developments in the field of antidepressant drugs during 1965 may be summed up as follows: 1. An increased understanding of the possible mechanisms of antidepressant drug action was gained through the study of their effects on central adrenergic and cholinergic neurotransmitters. 2. The availability of several drugs with differential types of useful antidepressant activity served to demonstrate that "mental depression'' is a "catch-allf7phrase which encompasses several disease syndromes of varying etiologies and requiring antidepressant drugs with either stimulant, tranquilizing, or antipsychotic properties. 3 . Some progress was made toward achieving a faster onset (two to four days) of action and a lessening of side effects with the desmethyl derivatives of active thymoleptics. 4. Advances in methodology of animal testing for antidepressant activity revealed definite qualitative differences between the antidepressant and tranquilizing agents. 5. On the basis of the mechanism of action of various effective antidepressant drugs, one could conceive of a biochemical etiology for mental depressive illness founded on the inability of the central nervous system to (a) elaborate sufficient amounts of neurotransmitter substance (possibly norepinephrine) (b) release adequate quantities of "active" neurotransmitters from cellular binding sites to the adrenergic synapses or (c) prevent a too rapid metabolic destruction of the critical neurotransmitter substance(s). 6. Clinical evaluation of antidepressant drugs still poses a major problem due to the complex nature of the disease, the hi h incidence of favorable placebo responses and spontaneous remiss ons.

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C e n t r a l Stimulants The c e n t r a l mechanism of a c t i o n of amphetamine s t i l l remains i n d i s p u t e . Since c e n t r a l catecholamine d e p l e t o r s ( r e s e r p i n e , a - W ) f a i l e d t o block amphetamine-induced motor s t i m u l a t i o n , f e l t t h a t amphetamine a c t s i r e c t l y on t h e CNS. s e v a r ~ 8 8 ~ ~ ~ $ o bO ~na t8h e~ ~ o t~ h e~r dhand, Stein8$ p o i n t s o u t t h a t amphetamine's f a c i l i t a t i n g e f f e c t on i n t r a c r a n i a l s e l f stimulation i n rats blocked by r e s e r p i n e and p o t e n t i a t e d by MA0 i n h i b i t o r s . Hence, he concluded t h a t t h e c e n t r a l stimulant e f f e c t s of amphetamine were mediated by catecholamine r e l e a s e . A novel mechanism h a s now been proposed by Weissman e t al.89a which is based on t h e experimental f i n d i n g t h a t t y r o s i n e T y c o x y l a s e i n h i b i t o r s ( e . g . , a-methyltyrosine) which block t h e biosynt h e s i s of dopamine and NE, a l s o i n h i b i t a l l t h e CNS e f f e c t s e x e r t e d by a m hetamine and amphetamine-like drugs (methamphetamine, Hence, t h e authors conclude t h a t t h e c e n t r a l phenmetrazine? responses induced by amphetamine r e q u i r e a ' ' c r i t i c a l l e v e l of NE a t t h e receptor" and " t h a t t h i s l e v e l d e r i v e s from a f u n c t i o n a l pool of norepinephrine i n t h e CNS h i g h l y s u s c e p t i b l e t o blockade of norepinephrine b i o s y n t h e s i s a t t h e t y r o s i n e hydroxylase s t e which is t h e r a t e - l i m i t i n g s t e p i n catecholamine b i o s y n t h e s i s . %b On t h e o t h e r hand, a-MMT which is a p o t e n t catecholamine-depleting agent, but does n o t i n t e r f e r e with NE b i o s y n t h e s i s , f a i l s t o antagonize t h e c e n t r a l e f f e c t s of amphetamine. I n essence, amphetamine may r e q u i r e t h e presence of f r e s h l y synthesized, r e a d i l y a v a i l a b l e NE t o produce i t s c h a r a c t e r i s t i c CNS e f f e c t s . C l i n i c a l s t u d i e s on a novel sympathomimetic ketone (F-1983) revealed t h a t t h i s substance was capable of i n c r e a s i n g d r i v e and spontaneous a c t h z i t y i n a group of c h r o n i c a l l y depressed and psychotic p a t i e n t s . 11.

=

.

CH3

yHC2H4CH3

("7

(XXXVI) F-1983 C e n t r a l s t i m u l a n t and a n t i t r e m o r i n e e f f e t s were d i s p l a y e d i n animals by a diphenylthiocarbamate (XXXVII). 81 A mild c e n t r a l stimulant (XXXVIII) was shown by Glasky and Simong2 romo t e ~ ~ ' t h e b i o s y n t h e s i s of RNA i n r a t b r a i n and by P l ~ t n i k o ~t o f a c i l i t a t e l e a r n i n g by i n c r e a s i n g memory and r e t e n t i o n of l e a r n e d behavior. This p r o p e r t y was n o t shared by o t h e r c e n t r a l s t i m u l a n t s . jd2NC OSC2H4NEt2

(XXXVII) (XXXVIII 1 (XXXIX) A s t r u c t u r a l l y s i m i l a r cgtpound (XXXIX) has been i n v e s t i g a t e d by G r e e n b l a t t and Osterberg. The pharmacologic spectrum of XXXIX l i e s between amphetamine and imipramine. The compound is

Sect. I

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a c e n t r a l e x c i t a n t with anorexigenic p r o p e r t i e s . The l a t t e r a r e more pronounced and longer l a s t i n g than those of amphetamine. Tolerance did n o t develop t o e i t h e r e f f e c t . The drug displayed only minimal cardiovascular e f f e c t s and w a s devoid of a n a l e p t i c p r o p e r t i e s . Like imipramine, it delayed t h e onset of r e s e r p i n e depression and i n h i b i t e d tetrabenazine depression. I t protected mice from maximum s e i z u r e s and prolonged b a r b i t u r a t e hypnosis. The Hallucinogens Most d r u s capable of p e n e t r a t i n g t h e CNS have s t r u c t u r a l r e l a t i v e s wh ch w i l l produce psychotomimetic e f f e c t s . T h i s a p p l i e s t o the a n a l g e t i c , antidepressant, a n t i c h o l i n e r g i c , a n e s t h e t i c , sympathomimetic, serotonergic and t r a n q u i l i z i n g drugs. It i l l u s t r a t e s perhaps more than anything e l s e the f i n e l i n e which we a r e s t r a d d l i n g between normal and pathologic emotional behavior and underscores t h e s e n s i t i v e chemical balance necessary f o r t h e maintenance of c e n t r a l homeostasis and presumably ttnormallt behavior. For back round materi reader is r e f e r r e d t o t h e following r e v ew a r t i c l e s . 9gy7 A m t comprehensive review on LSD has been published by Hoffer The s o c i a l and t h e r a p e u t i c fmplications conGQrning the use of LSD2 have been discussed by Cole an Savage and S t o l a r o f f , 200 and McGlothlin and S. Cohen. f 0 f a t z , S t r u c t u r e - a c t i v i t y r e l a t i o n s h i p s with regard t o the c e n t r a l stimulant and psychotomimetic p r o p e r t i e s of the basic g l y c o l a t e e s t e r have been presented by B i e l e t a1.102 and Abood and B i e l . 803 A . Analgetics Psychotomimetic p r o p e r t i e s have been reported f o r dexoxadrol Io4 and cyclazocine 05 i n man. In animals, both drugs were devoid of a n a l g e t i c a c t i v i t y but displayed morphine antagonism. I1I .

f

‘si

.!%;

.88

(XL) Dexoxadrol

( X L I ) Cyclazocine

Anesthetics A s an a n e s t h e t i c , phencyclidine (SernylTM) is q u i t e unique from t h e standpoint of high potency, lack of r e s p i r a t o r y and circulafBgy depresfhqn o r disturbance of c a r d i a c rhythm both i n animals . I t s ps chotomimetic p r o p e r t i e s have been and man reviewed by Davles and Beech. 15s The s i m i l a r i t y i n sympathomimetic p r o p e r t i e s phencyclidine, desoxyephedrine and cocaine prompted Chen e t al. t o speculate on a c e n t r a l adrenergic mechanism of a c t i o n , even though the i n s e r t i o n of a methylene group between t h e phenyl and cyclohexyl B.

188

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r i n g t o simulate a P-phenethylamine abolished a l l a c t i v i t y . A simple, s p e c i f i c and q u a n t i t a t i v e t e s t f o r t h e assessment of c a t a l e p t i c a c t i v i t y of phen l i d i n e - t y p e compounds i n pigeons The c a t a l e p t i c e f f e c t i s has been developed by Chen. a s c e r t a i n e d by t h e loss of r i g h t i n g r e f l e x without "head drop" over a wide range of dosage A s t r u c t u r e - a c t i v i t y s t u d y was conducted by Maddox e t a l . The most p o t e n t c a t a l e p t i c a g e n t s were those where R = H , ? i i e t h y l o r methoxy and N ( R , R ' ) was p i p e r i d i n o , p y r r o l i d i n o , 3-methylpiperidino, P-methoxyethylamino, methylamino o r ethylamino.

ErB

(XLII

Phenc c l i d i n e

(s e e +

(XLIII) Phencyclidine Derivat i v e s

Adrenergic Agents The proponents of an abnormal m i n e metabolism i n schizophrenic p a t i e n t s received f u r t h e r support f o r t h e i r s p e c u l a t i o n from t h e experimental f i n d i n g of Friedhoff and Van Winkle 11* t h a t 3,4-dimethoxyphenethylamine (DMPEA) was excreted i n t h e u r i n e of schizophrenic p a t i e n t s , but could never be i s o l a t e d t h e u r i n e of normal p a t i e n t s . Bourdillon e t &.I were a b l e t o demonstrate t h a t when t h e schizophrenic population was f u r t h e r subdivided, c e r t a i n groups showed high c o n c e n t r a t i o n s o f t h i s amine i n t h e u r i n e . For an up-to-date l i s t of r e f e r e n c e s on t h i s c o n t r o v e r s i a l s u b j e c t , t h e r e a d e r i s r e f e r r e d t o an E d i t o r i a l . 1 l 4 Friedhoff and Van Winkle115 f u r t h e r found t h a t l i v e r homogenates obtained from b i o p s i e s of schizophrenic p a t i e n t s were capable of 0-methylating both 'OH' groups of dopamine, whereas those obtained from normal s u b j e c t s were unable t o convert dopamine t o DMPEA. I n c a t s , DMPEA produced a c a t a t o n i c e f f e c t s i m i l a r t o t h a t of mescaline. 116,117 D . The C e n t r a l A n t i c h o l i n e r g i c s I t had p r e v i o u s l y been concluded by Bie1118 t h a t p o t e n t a n t i c h o l i n e r g i c a c t i v i t y w a s a p r i m a r y p r e - r e q u i s i t e f o r inducing psychotomimetic e f f e c t s both i n animals and man, but t h a t n o t every potent a n t i c h o l i n e r g i c d r need n e c e s s a r i l y be a psychotogenic agent. Giarman and PepeuBg r e p o r t e d t h a t r a t b r a i n l e v e l s o f a c e t y l c h o l i n e were reduced by t h e psychotomimetic g l y c o l a t e e s t e r s , but n o t by non-psychotogenic a n t i c h o l i n e r g i c s of s i m i l a r s t r u c t u r e . A s i n g l e i n j e c t i o n of 0.5 mg/kg of scopolamine t o r a t s which had been t r a i n e d f o r a s h o r t p e r i o d , produced an amnesic e f f e c t of learned performance which elated well with Both e f f e c t s t h e decrease i n t o t a l r a t b r a i n AcCh l e v e l s . were abolished by e s e r i n e and amphetamine. On t h e o t h e r hand, C.

€30"

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e l , Ed.

overtrained r a t s experienced no amnesic e f f e c t s , even though b r a i n AcCh l e v e l s were decreased t o t h e same e x t e n t . The authors concluded t h a t only r e c e n t memory may be c h o l i n e r g i c a l l y mediated. I n adequate doses, scopolamine disrupted s e v e r e l y both the s i t i o n and r e t e n t i o n of passive avoidance response in r a t s . I n a r e c e n t paper by Deutsch e t a1.122 t h e i n j e c t i o n of t h e a n t i c h o l i n e s t e r a s e drug, diisopropyl fluorophosphate, i n t o t h e hippocampi of r a t s , 30 minutes a f t e r escape l e a r n i n g , produced a p a r t i a l amnesia l a s t i n g f o r f i v e days. C e n t r a l l y , scopolamine had t e n times t h e a c t i v i t y of a t r o p i n e , whereas i n t h periphery, t h e r a t i o was c l o s e r t o t w o t o one, r e s e c t i v e l y . The compound (Ro 3-1172) was reported by Parkes lq3t o have 50 times t h e CNS a c t i v i t y of a t r o p i n e .

88Yui-

123

3I

Id2C(OH)C02C2H,N

(XLIV) RO 3-1172 S h o r t - l a s t i n g psychotomimetic e f f e c t s (two hours) were induced i n humans by N-allylnoratropine ( 5 mg/man). I n the periphery compound only had 1/16 the autonomic a c t i v i t y o f a t r o p i n e . i2thiS The i n t e r a c t i o n between phenothiazine t r a n q u i l i z e r s i n small doses and the c e n t r a l a n t i c h o l i n e r g i c s , a t r o p i n e , scopolamine, and Ditran (JB-329) was studied by Gershon e t al.125 Chlorpromazine, a t a dose of 0.1 mg/kgtpotentiated t h e e f f e c t s of 0.05 mg/kg of Ditran producing a comatose-like s t a t e i n human s u b j e c t s . Imipramine d i d not p o t e n t i a t e t h e a c t i o n of Ditran. Hence, t h i s t e s t could be applied i n dogs t o d i f f e r e n t i a t e an a n t i d e p r e s s a n t from a t r a n q u i l i z i n g drug. Buehler et a l . l 2 6 synthesized a number of t h i o l analogs of basic g l v c o l a t e e s t e r s which were considerablv weaker a s psychotomimet i c agents than t h e corresponding- oxygen analogs.

= $, cycloalkyl Rl= CH3, C2H5 R

The influence of stereochemical f a c t o r s on a n t i c h o l i n e r g i c p i p e r i d y l g l y c o l a t e s have been psychotomimetic a c t i v i t y of so d i s c w s e d by Gabel and Abood. 137 Summary Present evidence suggests t h a t mental depression may be the cauee o r consequence of a breakdown i n c e n t r a l chemical homeos t a s i s , i . e . , an imbalance between two mutually a n t a g o n i s t i c c e n t r a l neurotransmitter systems, which may possibly be adrenerg i c - l i k e and cholitlergic-like In c h a r a c t e r . Chemical c o r r e c t i o n of t h i s imbalance through drug treatment has afforded a means of accornplisAing remissions i n acute, nonpsychotic depressions.

Chap. 2

Stimulants

27 -

Biel

References L. Klerman and J . 0. Cole, Pharmacol. Rev., lJ-, 101 (1965). L. E . H o l l i s t e r , C l i n . Pharmacol. Therap., 555 (1965). 3 . J. R . Markette and Y. H. H a r r i s , Dis. Nerv. S y s t . , 3.42 (1965). 4. D. M. G a l l a n t , M. P. Bishop, W. Nesselhof and T. E. Fulmer, Curr. Therap. R e s . , 6, 69 ( 1 9 6 4 ) . 5. H. B r i c k , W. H. Doub, and W. C . Perdue, I n t e r n . J. Neuropsychiat., 1,325 ( 1 9 6 5 ) . 6. A. M. Kasich, Cum. Therap. R e s . , 1,542 (1965). 7. B r i t i s h P a t e n t 1,003,686. 8. J. Knoll, Z. E c s e r i , K. Kelcnen, J . Nievel and B. K n o l l , Arch. i n t . Pharmacodyn., 154 (19651. 9. J. F i n k e l s t e i n , E. Chang and J. Lee, J. Med. Chem., 8. 432 (1965). 10. G. A. Youngdale, D. G. Anger, W. C. Anthony, J. P. DaVanzo, M. E. G r e i g , R . V. Heinzelman, H. H. Keasling and J. Szmuszkovicz, J . Med. Chem., 1,,415 (1964). 11. P. A. M. J a n s s e n , U. S. P a t e n t 3,161,637 (1964). 1 2 . The Upjohn Co., French P a t e n t 329lM. 573 (19621. 13. H. Azima, D . A r t h u r s , A. S i l v e r and F. J. Azima, Am. J. P s y c h i a t . , 2. 14. J . B. H e s t e r , M. E. Greig, W. C. Anthony, R . V. Heinzelman and J. Szmuszkovicz, J. Med. Chern., 1, 274 ( 1 9 6 4 ) . 456 (1964). 15. L. I. Goldberg, J. Am. Med. Assoc., 15a. J. M. C u t h i l l , A. B. G r i f f i t h s and D. E. B. Powell, L a n c e t , L. 1076 ( 1 9 6 4 ) . 763 ( 1 9 6 4 ) . 15b. Council on Drugs, J. Am. Med. Assoc., 945 , (1965). 1 5 ~ . E d i t o r i a l , L a n c e t , I16. D. M. Tedeschi and E. J. Fel-lows, S c i e n c e , %, 1225 ( 1 9 6 4 ) . 456 (1964). 17 * L. I . Goldberg, J. Am. Med. Assoc., 18. J. H. B i e l , J. S p o e r l and E. S p r e n g e l e r , B r i t i s h P a t e n t 961,313 ( 1 9 6 4 ) . 19- C. L. Z i r k l e and C. K a i s e r , i n Psychopharmacological Agents, Vol. I , e d . M. Gordon, Academic Press, New York-London, 1964, 445. 20. A . H o r i t a , I n t . J. Neuropharmacol.,.lC, 337 (1965). G. M. E v e r e t t , Second Catecholamine Symposium, Milan, I t a l y , J u l y , 1965, p u b l i s h e d i n 21. (1966). Pharm. Revs., 22. J. A. R i d e r , H. C. Moeller and E . A. DeFelice. T o x i c o l . & Appl. Pharmacol., 1,438 ( 1 9 6 5 ) . 22a. H. Freeman, I . Karacan, W . E. Waterman, A. U. Khan, F. L. Zimmer, A . F e l d s t e i n , C . 0. Tedeschi and E. A. DeFelice. I n t e r n . J. N e u r o p s y c h i a t r y , 1 c5], 513 (19651. J. J. S c h i l d k r a u t , Am. J. P s y c h i a t . . 112, 509 (1965). 23. 856 (1963). 24. S. S p e c t o r , N . Y. Acad. S c i . , 25. C . G. I n g v a r s s o n , A r z n e i m i t t e l F o r s c h . , 3,849 (1965). 86 (1965). 26. S. S p e c t o r , A . Sjoerdsma and S. Udenfriend, J . Pharmacol. E x p t l . Therap.. A. Sjoerdsma, Pharm. Revs., 673 ( 1 9 6 6 ) . 27. '28. A. F e l d s t e i n , H. IIoagland. M. R. Oktem and H. Freeman, I n t . J. N e u r o p s y c h i a t . , L, 384 ( 1 9 6 5 ) . 29 * A. F e l d s t e i n and H. Freeman, C l i n . Pharmacol. T h e r a p . , 6 , 470 (19651. A. P l e t s c h e r , Pharm. Revs., 1 2 1 (1966). 30. 31. R . M. Atkinson and K. S. Ditman, C l i n . Pharmacol. Therap.. 6. 631 (1965). 32. I . J . Kopin, J. E . F i s c h e r , J. M. Musacchio, W. D. Horst and V. K. Weise, J . Pharmacol. E x p t l . Therap., 186 (1965). 33. L. I. Goldberg, J. Am. Med. Assoc., E, 456 (1964). 448 (1964). 34. J . 0. Cole, J . Am. Med. Assoc., 35. G. L. Klerman and J. 0. Cole, Pharmacol. Rev., Q, 101 (1965). 36. L. E. H o l l i s t e r , C l i n . Pharmacol. Therap., 6. 555 (1965). 37 * N. K l i n e , J. Am. Med. Assoc.. E,732 (1964). 38. J. J. S c h i l d k r a n t , Am. J. P s y c h i a t . . 112, 509 (1965). A. P l e t s c h e r . K. F. Gey and P. Z e l l e r , Progr. Drug R e s . , 2, 417 (1960) I I n t e r s c i e n c e ] . 39. J. H. B i e l , A. H o r i t a and A. E. Drukker, i n Psychopharmacological Agents, Vol. I , e d . M. Gordon, 40. Academic P r e s s , New York-London. 1964, 359. 41. C. L. Z i r k l e and C. K a i s e r , i n Psychopharmacological Agents, Vol. I , ed. M. Gordon, Academic P r e s s , New York-London, 1964, 445. 42. R . Kuhn, Schweiz. Med. Wochsch., Q, 1135 (1957). 43. F. H P f l i g e r and V. Burckhardt, i n Psychopharmacological Agents, Vol. I , ed. M. Gordon, Academic P r e s s , New York-London, 1964, 35. 1. 2.

G.

6,

a,

=,

.

a,

s,

2

m,

9.

9,

m,

z,

m,

Sect. I

28 -

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CNS Agents

B i e l , Ed.

48a. 49. 50 * 51. 52: 53. 54. 55.

E. B. Sigg, Can. Psychiat. Assoc. J., 4. Spec. Suppl.. 7 5 (1959). A. Kaumann. N. Basso and P. Armendia, J. Pharmacol. Exptl. Therap., 54 (1965). R. C. Ursillo and J. Jacobsen, J. Pharmacol. Exptl. Therap.. 247 (1965). A. Jori and S. Garattini, J. Pharm. Pharmacol., lJ, 480 (1565). W. Theobald, 0. &ch, H. A. Kunz, C. Morpurgo, E. G. Stenger and G. Wilhelml, Arch. int. Pharmacodyn., 560 (1964). J. Axelrod. G. Hertting and L. Potter, Nature, Lond.. 297 (1962). J. Glowinski and J. Axelrod, Nature, 1318 (1964). L. L. Iversen, J. Pharm. Pharmacol., 3, 62 (1965). H. Thoener:, A. Huerlimann and W. Haefely, J. Pharmacol. Exptl. Therap., %, 405 ( 1 9 6 4 ) . W. Haefely, A . Huerlimann and H. Thoenen, Helv. Physiol. Acta, 22, 15 (1964). F. Sulser and F. Soroko. Psychopharmacologia, 8. 191 (1965). F. Sulser, M. H. Bickel and B. B. Brodie, J. Pharmacol. Exptl. Therap., 144, 321 (1964). J. H. Biel. P. A. Nuhfer, W. H. Haya and H. A . Leiser, Ann. N. Y. Acad. Sci., $, 251

5657 * 58 * 59. 60. 61.

F. Sulser, M. H. Bickel and B. B. Brodie, J. Pharmacol. Exptl. Therap., 321 (1964). A. Ribbentrop and W. Schaumann, Arzneimittel-Forsch., 3, 863 (1965). A. Ribbentrop and W. Schaumann, Arzneimittel-Forsch., B,863 (1965). A. M. Monro. R. M. Quinton and T. I. Wrigley, J. Med. Chem., 6, 255 (1963). N. J. Giarman and G. Pepeu, Brit. J. Pharmacol., 9, 123 (1964). Z. P. Horovitz. A. R. Furgiuele, L. J. Brannick, 3. C. Burke and B. N. Craver, Nature,

44. 45. 46. 47 * 48.

62. 62a. 63. 64. 6566. 67. 68. 69 * 70.

-

71.

72 73. 74. 75.

76. 77. 78 * 79. 80. 81. 82. 83.

84. 85. 86. 87 88. 88a. 88b. 88c. 886. 8989a. 89b.

-

148.

B,

a,

N,

z,

(1962).

w,

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234 (1963). I. W. Sletten, X. Pichardo and S. Gershon, Curr. Therap. Res.. 1. 609 (1965). R. Kuhn. Psychopharmaeologia. 8, 201 (1965). A. Ribbentrop and W. Schaumann, Arzneimittel-Forsch., 863 (1965). J. 0. Cole, J. Am. Med. Assoc.. 448 (1964). J. E. Overall, L. E. Hollister. F. Meyer. I. Kimbell, Jr. and J. Shelton, J. Am. Med. Assoc., 605 (1964). G. L. Klerman and J. 0. Cole, Pharmacol. Rev., lJ-, 101 (1965). L. E. Hollister. Clin. Pharmacol. Therap., 6 . 555 (1965). H. Wechsler. G. H. Grosser and M. Greenblatt, J. Nerv. Ment. Dis., 141,231 (1965). N. Kline, J. Am. Med. Assoc., 732 (1964). F. J. Ayd. Dis. Nerv. Syst., 26. 719 (1965). V. #. Pennington, Am. J . Psychiat.. 120. 115 (1964). T. E. Hanlon. J . New Drugs, k, 52 (1964). E. Incas Smith, J. National Med. Assoc., 284 (1965).

x,

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a,

443 (1965). D. M. Gallant, M. P. Bishop, W. Nesselhof and T. E. Fulmer. Curr. Therap. Res., 6 . 69 (196%). J. R. Markette and Y. H. Harris, Dis. Nerv. Syst., 42 (1964). A. M. Kasich. Curr. Therap. Res., 2 , 542 (1965). E. DePerrot, Psychiat. Neurol., 146,341 (1963b.

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(1964). J. Angst acd H. Kind, Schweiz. Med. Wochschr., 2, 759 (1964). 0. H. Arnold, H. Bauer and K. Cmyral. Arzneimittel-Forsch.. 14. 510 (1964). H. Freeman, M. R . Otkem, M. W. Kristofferson and C. K. Gorby, Curr. Therap. R e s . , 1, 655 (1965) * I. W. Sletten, X. Pichardo and S. Gershon, Cum. Therap. Res., 1, 609 (1965). J. H. Biel, in Advances in Chemistry Series, No. 45, ed. F. W. Schueler, American Chemcal Society, Baston, Pa., 1964, 114. H. K. Davis, H. F. Ford, J. P. Tupin and!A; Colvin, Dis. Nerv. Syst., 179 (1964). M. Fink, D. F. Klein and J. C. Kramer, Psychopharmacologia, 5, 27 (1964). H. Brick, W. H. Doub. and W. C. Perdue, Intern. J. Neuropsychiat., 1,325 (1965). A. M. Kasich. Cum. Therap. Res., 1, 542 (1965). J. M. VanRossum. J. B. VanDerSchoot and J. A. Th. M. Hurkmans, Experientia, 18,229 (1962). A . Randrup, I. Munkvad and P. Udsen. Acta Pharm. Tox., 20, 145 (1963). R. M. Quinton and G. Halliwell, Nature, 200, 178 (1963). L. Stein. Fed. Proc.. 836 (1964). A. Weissman, B. K. Koe and S. S. Tenen, J. Pharmacol. Exptl. Therap. s,339 (1966). M. Levit, S. Spector, A. Sjoerdsma and S. Udenfriend, J. Pharmacol. Exptl. Therap., 148, 1 (1965).

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100. 101. 102.

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x,

106.

x,

m,

m.

x,

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Sect. I Chapter 3 .

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CNS Agents

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Sedatives, Hypnotics, Anticonvulsants, Muscle Relaxants, Gene r a1 Anesthetics

Cornelius K. Cain, McNeil Laboratories, Inc., F o r t Washington, P a .

-

The classification of a given drug according to the pharmacoIntroduction logical actions listed i n the title (plus tranquilizers discussed in Chapter 1) is recognized as a r b i t r a r y and dependent upon dosage being used. The following discussion is divided m o r e on the basis of established o r projected clinical utility than on the basis of widely different pharmacological proper ties o r chemical s t r u c t u r e .

1 Some y e a r s ago, Chen and P o r t m a n undertook a quantitative approach to the problem. They determined the C D 5 0 1 of ~ a convulsant in mice p r e treated with graded doses of a depressant. Plotting these values gave a graph showing two points of inflection, and t h r e e corresponding straight lines were constructed. The slopes of these lines were interpreted a s r e p resenting the sedative, hypnotic and anesthetic potencies of the depressant. The i n t e r s e c t s represented minimal hypnotic and anesthetic doses. The authors concluded that this approach was useful in indicating that a given d e p r e s s a n t drug might be m o r e useful as a hypnotic, an anesthetic o r as a sedative.

;"8

Sedatives and Hypnotics - Several a r t i c l e s d e s c r i b e the favorable r e s u l t s obtained with nitrazepam, Mogadona, RO 4-5360 (I). The pharmacology was thoroug y investigated by Randall and coThey postulate that the sleepworkers inducing effect is due not to a d i r e c t effect on the a r o u s a l system, but to a reduction of stimuli acting on it. Metabolic studies O2 showed the unchanged drug as well a s i t s 7-amino and 7-acetylamino derivative in human plasma and urine. \ I 3 Clinical studies by Wyss and Mgder in 200 patients gave good r e s u l t s in onset and duration of sleep a t doses of 5 to 10 mg. At higher doses (up to 200 mg.), tolerance was excellent. They state h a t the mechanism of action differs f r o m known hypnotics. Lanoir, Dolce and Chirinos4 found that in a battery of neurophysiological t e s t s in cats, nitrazepam and diazepam showed the s a m e type of activity in many respects, such as action on spontaneous rhythm, evoked responses, etc. Both are potent anti-convulsants. The m a j o r difference is that nitrazepam induces a lasting and profound slee while diazepam a c t s essentially as a relaxant and not as a hypnotic. Borck

7

9.

!?

Chap. 3

Depressants

Gain

31 -

reported that the drug in doses of 5 to 15 mg. was a highly suitable hypnotic in psychiatric patients. E g e r t and Jahn6 found it gave v e r y good to good results in 75% of a wide variety of clinical c a s e s . P a r t i c u l a r l y noteworthy were i t s new type of mechanism of action when compared with b a r biturates, i t s low toxicity and i t s u s e l e s s n e s s f o r suicidal pur o s e s . In 40 children ranging in age f r o m a few days to 11 y e a r s , Matthes 7p induced daytime sleep in 50% of the c a s e s . B e s t results were obtained in infants up to 12 months of age. About 10 y e a r s ago, the hypnotic, anticonvulsant and sedative p r o p e r ties of a s e r i e s of 2-alkyl-3-aryl-4(3H)quinazoloneswere reported by Gujral and co-workers 8~ 9 and confirmed by B o i s s i e r . l 0 Recently, a s e r i e s of 79 compounds of this type was examined by Leszkovszky, Erdely and Tardos" who reported that compound I1 showed the highest o r a l activity. Swift, Dickens and Becker12 published a thorough pharmacological study of this compound in 1960. Clinical studies were published by s e v e r a l investigators 13, 14J15J16,17 who 0 compared methaqualone to glutethimide, chloral hydrate and cyclobarbital. A r e cent l e t t e r to the editor cites four I1 patients who consumed l a r g e amounts of the drug daily f o r extended periods, raising the question of physical dependence. In 1965, compound 11 was marketed a s a hypnotic and sedative in the f o r m of 150 m g . tablets as methaqualone (Quaaludem).

qJ$

Fenimide i s the non-proprietary name recently adopted19 for 3-ethyl-

2-methyl-2-phenylsuccinimide(111) which was described by Chen and BassZO

a s a sedative agent comparable to m e p r o bamate and phenobarbital. It protects against s t r e s s -induced u l c e r s while m e p r o bamate and phenobarbital do not.

Q$ . . f . 2Hc3Hc 111

At the same time, the non-proprietary name trimetozine was adopted for 4-(3, 4, 5-trimethoxybenzoyl)morpholine. This compound (IV) was r e o r t ed e a r l i e r by Vargha and co-workers 8 , 2 2

d3

as being selected f r o m a l a r g e s e r i e s of alkoxybenzamides f o r clinical t r i a l as a neurosedative in Hungary. Of particular 6 7 - C OCH3 i n t e r e s t in their p a p e r s is the r e p o r t of OCH3 the marked influence on pharmacological activity of changes in position and/ o r IV nature of the afkoxy groups. B o i s s i e r and c o - w o r l ~ e r sstated ~ ~ that tests in animals show the compound to be a sedative but not a hypnotic even a t toxic doses.

r

/ \

32

Sect. I - CNS Agents

B i e l , Ed.

Metabolic studies of the optical antipodes of glutethimide (V) (Doriden@)by Keberle, Riess and HoffmannZ3 a r e of especial interest since the authors showed stereospecific metabolism in dogs. The dextrorotatory form of V was hydroxylated in the ring to give mainly V I (isolated a s the glucuronide) and VII, resulting from dehydration. The levorotatory f o r m of V was hydroxylated in the ethyl group to give mainly VIII (isolated a s the glucuronide) and IX, resulting from l o s s of acetaldehyde. Total r e covery of these products was 96% of theory. No products resulting f r o m ring opening were detected. CH2CH3

p CH2CH3 I

k

v

VIII

IX

The sedative and hypnotic properties of thalidomide have been almost forgotten in view of i t s reported embryotoxic effects. Recent metabolic studies of thalidomide in abbits, r a t s , mice and guinea pigs by SchuL macher, Smith and Williams 2 4 showed that up to 12 hydrolysis products appear in the urine. These products a r e the same a s those obtained from thalidomide in aqueous solutions a t pH values above 6, 25 and can be accounted for by initial hydrolysis of the phthalimide ring followed by hydrolys i s of the glutarimide ring. E a r l i e r , the same group of investigatorsz6 had studied the relationship of embryotoxic activity and chemical structure in a s e r i e s of compounds related to thalidomide and had concluded that a phthalimide group was important in determining teratogenic activity; and, in a recent article, 27 suggest that the reactivity of the drug towards certain natural diamines such a s spermidine, putresciae, etc., may be of significance in relation to its biological properties. Anti-convulsants - A s in previous years, many compounds were tested and reported to be active a s anti-convulsants during 1965. No new drugs for this use were marketed in the United States, and none marketed in other countries appear to offer considerable advantages over those in general use. A recent review by Millichap28 discusses clinical and EEG indications, efficacy and toxicity of some 2 0 drugs in current use in this field.

Chap. 3

Depressants

Gain

33 -

Central Muscle Relaxants - No new drugs in this field were introduced in the domestic market during 1965. Several reports were published of clinical t r i a l s of various compounds in severe spastic conditions. Bhargava and S r i ~ a s t a v astudied ~~ the anti-tetanus activity in cats of central muscle relaxants and found 3210220, 3-(q-chloropheny1)-3-hydroxy-2,2-dichloropropyl carbamate (X) to be the most potent and longest-acting of 11 compounds tested. Hendrickse and Sherman30 found CHOHCCSLCHZOCONHZdiazepam (Valium@)an effective muscle relaxant in children suffering from X tetanus, although it was not very effective in controlling convulsive spasms. Marsh31 obtained excellent results in 10 of 26 severely cerebralpalsied children using o r a l doses of diazepam in a controlled study, confirming e a r l i e r reports of effectiveness in adults similarly affected. Encouraged by the results of Berman, Noe and Goodfield3’ using chlorzoxazone in cerebral-palsied patients abandoned to supportive care, Darienzo 33 used a combination of chlorzoxazone and acetaminophen and obtained a change from severe to mild symptoms in 12 of 15 children.

A metabolic study of chlormezanone (Trancopala) in rat, dog and man by McChesney and co-workers34 showed that the compound was excreted as such. A review of benzazoles; chemistry, pharmacology and clinical application a ~ p e a r e d ?SKF ~ 13,436, 3 -amino5-trifluoromethyl- 1H -indazole (XI) was reported by Santella and c o - ~ o r k e r to s~~ be a muscle relaxant in r a t s , cats, dogs, F3C&NH2 rabbits and monkeys.

XI Anesthetics (a) - D a t a from thousands of patients were examined for possible relation between post-operative liver damage and anesthesia. Herber and S p e ~ k reviewed t ~ ~ findings in about 20,000 cases and estimated that one case of hepatic necrosis may be expected in about 800 halothane anesthetics. They suggest that careful selection of patients should minimize liver necrosis in the continued use of this valuable anesthetic. Gingrich and Virtue38 reviewed records of nearly 3800 cases using fluorinated hydrocarbons and over 20,000 cases using other inhalation agents a s well a s 48, 000 non-surgical patients. They doubt that either halogenated hydrocarbons o r other anesthetic agents p e r s e have been of significance in the production of hepatic necrosis.

Sect. I

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B i e l , Ed.

OH3 g

(b) Injection Anesthetics

XI1

XI11

-

McCarthy, Chen, Kaump and E n ~ o studied r ~ ~ the general anesthetic and o t h e r pharmacological p r o p e r t i e s of CI 581 (XI), an analog of phencyclidine (Se rnyl@) (XIII) in eight species of animals and concluded that XI1 showed a l e s s e r d e g r e e of CNS XIII. stimulation However, and of Domino, b r i e f e r Chodoff durationand than Corssen40 found that in humans, XIII, like XI, was hallucinatory and that skeletal muscle tone was increased. They sugg e s t the t e r m "dissociative anesthetic" for this c l a s s of agents.

s ~ ~by G. The earlier r e p o r t s by H. Laborit and c o - ~ o r k e r and Laborit and co-workers4' on the clinical u s e of sodium y -hydroxybutyrate f o r sedation, hypnosis and general anesthesia stimulated s e v e r a l other authors to investi4gte the pharmacology of this compound. 43s44,45 B e s s m a n and Skolnick found that the d e p r e s s a n t action paralleled the concentration in brain of the lactone and not of the anion. Recently, Winters and S p ~ o n e suggest r ~ ~ that a r e - a p p r a i s a l of the clinical usefulness of this drug m a y be in o r d e r , based on the epileptiform EEG patterns and grand ma1 s e i z u r e s in cats after intraperitoneal administration of 0,7 to 1.0 g/kg. Propanidid (XIV) and a few other substituted phenoxyacetamides have been investigated f u r t h e r as very short-acting intravenous anesthetics. Gunner and ~ o - w o r k e r sfound ~ ~ propanidid useful in electroconvulsive therapy in 70 patients. They found the OCHZCON(CzH5)z duration of unconsciousness averaged four minutes a t a dose of 5 mg/Kg. and s i x minutes a t a dose of 7 mg/Kg. They a s c r i b e the brevity of action to hydrolysis of the e s t e r group by e s t e r a s e s . E i s t e r e r and c o - ~ o r k e r found s ~ ~ the drug CH2C OOC 3H very suitable in 96 ambulatory patients r e XIV quiring anesthesia of up to five minutes' duration. Hewitt, Hamilton, O'Donnell and Dundee50 reported that, while propanidid showed a slightly higher incidence of venous thrombosis than thiopentone o r methohexitone, the incidence was not enough to influence clini cal acceptability

6"'". .

Adjuncts to Anesthesia (a) - Lunsford and coworkers5l synthesized a s e r i e s of substituted pyrrolidinones (XV) and

Chap. 3

Depressants

Cain

35 -

studied their pharmacological properties. Some were stimulants of r e s p i ration and the CNS, and m o s t of these showed p r e s s o r activity; o t h e r s were depressants. One of the stimulants (XVI) was selected f o r f u r t h e r study.

xv

R = alkyl, cycloalkyl, benzyl B = basic residue

o & c H 2 cR H2B

XVI B R = morpholino ethyl

Dopram@Doxepram

52 E v e r s , Malik and Dobkin found doxepram to be a s effective a s d-amphetamine in shortening the recovery time in dogs given a standardized dose of thiopental; no untoward effects were observed. They a l s o used the drugs a s an intravenous infusion in 50 healthy female patients and found it effective for stimulating respiration (both tidal volume and r e s p i ration r a t e ) without producing any appreciable circulatory changes.

53

Mauro and co-workers studied 52 patients to whom doxepram was given and 23 controls; all were anesthetized with thiopental. A few seconds after a single injection of 0 . 3 mg/Kg. of doxepram, t h e r e was a marked i n c r e a s e in tidal volume to levels approaching control values. Noe, Borrillo and G r e i f e n ~ t e i n injected ~~ 0. 5 mg/Kg. doses into 20 patients anesthetized with (1) pentobarbital-pentothal, (2) nitrous oxideoxygen o r ( 3 ) halothane -nitrous oxide and found r e s p i r a t o r y stimulation with m o r e o r l e s s arousal in a l l t h r e e groups. Brief E E G changes were observed in five subjects and m o s t c a s e s showed moderate hypertension; otherwise, there were no side effects. (b) - Combinations of neuroleptic agents and narcotic analgesics have been widely used in surgical procedures with o r without inhalation o r injection anesthetics. Such combinations a r e r e f e r r e d to a s neuroleptanalgesics and a r e usually considered a s adjuncts to anesthesia. Proceedings of a Symposium held a t Edinburgh were published. 6 8 During 1965, some 20 to 30 a r t i c l e s appeared concerning clinical studies with Innova@, a combination of the neuroleptic droperidol (XVII) and the analgesic fentanyl (XVIII). Contributions by the m o s t active workers

0

XVII

XVIII

36

Sect. I

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CNS Agents

B i e l , Ed.

in the field a r e : Israel, Jansen and Dobkin;” Corssen, Chodoff, Domino and Kahn;56 DeCastro, Mundeleer and B a ~ d u i n :Gorodetzky ~~ and Martin; 58 Aubry, Denis, Keeri-Szanto and Parent;59 and Gemperle and Buhler. 60 Pharmacological studies using the combination of the two drugs were reported by Dobkin and co-workers;61, 62 Chodoff and D o m i n 0 ; 6 ~and Canellas, Roquebert and Courtois. 64 A combination of the two d r u s was marketed during 1965 as Innova@-Vet. Yelnosky and Fieldg5 investigated i t s u s e i n s i x species of animals and found it m o s t useful in dogs. Franklin and Reid66 obtained good to excellent r e s u l t s in 564 out of 601 surgical procedures usin various b r e e d s of dogs. Mortelmans, Marsboom and Vercruyssee’ reported highly successful r e s u l t s in 174 t r i a l s using p r i m a t e s and lower monkeys.

Chap. 3

D e p r e s s a n ts

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References (1) G. Chen and R. P o r t m a n , A.M.A. A r c h . Neurol. P s y c h i a t . 68, 498 (1952). L. 0. Randall, W. Schallek, C. Scheckel, R. E. Bagdon and J. (2) Rieder, Schweiz. Med. Wochschr. 95, 334 (1965). S. W w .zy -ie Med. Wochschr. 2, 338 (1965). (3) J. Lanoir, G. Dolce and E. Chirinos, Compt. Rend. SOC.Biol. (4) 431 (1965). W . F. Borck, A r z n e i m i t t e l - F o r s c h . 1155 (1965). (5) (6) H. E g e r t and 0. Jahn, A r z n e i m i t t e l - F o r s c h . l5, 1159 (1965). (7) A. Matthes, A r z n e i m i t t e l - F o r s c h . l5, 1157 (1965). (8) M. L. Gujral, P . N . Saxena and R. S. Tiwari, Indian J. Med. R e s e a r c h 43, 637 (1955), Chem. A b s t r . E, 6662b (1956). (9) M. L. Gujral, K. N. S a r e e n and R. P. Kohle, Indian J. Med. 51 15787h (1957). R e s e a r c h 45, 20? (1957), C h e m . A b s t r . -’ (10) J. R. B c i s s i e r , T h e r a p i e 2, 30 (1958). (11) C. Leszkovszky, I. E r d e l y and L. T a r d o s , A c t a P h y s i o l . Acad. Sci. Hung. 27, 81 (1965), Chem. A b s t r . 62, 16782g (1965). (12) J. G. Swift, E. A. Dickens and B. A. B e c k e r , A r c h . I n t e r n . 112 (1960). Pharmacodyn. (13) A. Ravina, P r e s s e Med. 3, 891 (1959). (14) R. Neubauer, Med. T i m e s s , 61 (1963). (15) N. Asbell, J. Am. G e r i a t . SOC. lo, 1032 (1962). (16) V , Matthews, H. E. Lehmann and T . A. Bau, Appl. T h e r . 6, 806 (1964). (17) T. W . P a r s o n s and T . J. Thomson, B r i t . Med. J. L, 171 (1961). (18) J. S. Madden, B r i t . Med. J. 1 , 676 (1966). 208 (1966). (19) J. Am. Med. A s s o c . *, (20) G. Chen and P. B a s s , A r c h . I n t e r n . P h a r m a c o d y n . E , 115 (1964). (21) L. Vargha, E . K a s z t r e i n e r , J. B o r s y , L. F a r k a s , J. Kuszmann and B . Dumbovich, Biochem. P h a r m a c o l . g, 639 (1962). (22) E. K a s z t r e i n e r , J. B o r s y and L. Vargha, Biochem. P h a r m a c o l . 651 (1962). (23) H. K e b e r l e , W . R i e s s and K. Hoffmann, A r c h . I n t e r n . P h a r m a c o d y n . 142, 117 (1963). (24) H. Schumacher, R. L. Smith and R. T. W i l l i a m s , B r i t . J. P h a r m a c o l . 25, 338 (1965). (25) H. Schurnacher, R. L. S m i t h and R. T . W i l l i a m s , B r i t . J. P h a r m a c o l . 25, 324 (1965). (26) S. F a b r o , H. Schumacher, R. L. Smith and R. T. W i l l i a m s , Life Sci. 2, 987 (1964). 1208 (1965). (27) S. F a b r o , R. L. Smith and R. T . W i l l i a m s , N a t u r e (28) J. G. Millichap, P o s t g r a d . Med. 37, 22 (1965).

m,

2,

z,

z,

-

m,

38 -

Sect. I

- CNS Agents

B i e l , Ed.

References

P

g,

(29) K . P. B h a r g a v a and R. K. S r i v a s t a v a , B r i t . J. P h a r m a c o l . 74 (1965). (30) R. G. H e n d r i c k s e and P. M. S h e r m a n , Lancet 1965, p. 737. (31) H. 0. M a r s h , J. Am. Med. A s s o c . &, 797 (1965). (32) H. H. B e r m a n , 0. Noe and F. Goodfield, D i s e a s e s Nervous S y s t e m 2!5, 430 (1964). (33) C. Darienzo, D i s e a s e s Nervous S y s t e m 27, 189 (1965). (34) E. W. McChesney, W . F. Banks, J r . , G. A. P o r t m a n a n d A . V . R . Grain, F e d e r a t i o n P r o c . (2), 418 (1966). (35) C. K . C a i n and A. P. Roszkowski in”Psychopharmacologica1 Agents:‘ Vol. I, M. Gordon, E d . , A c a d e m i c Press, New York, N. Y. 1964, Chap. 10. (36) P. J. Santella, D. H. Tedeschi, J. J. Lafferty, C. L. Z i r k l e and E . J. Fellows, P h a r m a c o l o g i s t ‘7, 164 (1965). 266 (1965). (37) R. H e r b e r and N. W. Specht, A r c h . I n t e r n a l Med. (38) T . F. Gingrich and R. W. Virtue, S u r g e r y = , 241 (1965). (39) D. W . McCarthy, G. Chen, D. H. K a u m p a n d C. E n s o r , J. New D r u g s 5, 21 (1965). (40) E. F. Domino, P. Chodoff and G. C o r s s e n , Clin. P h a r m a c o l . T h e r a p h , 279 (1965). (41) H. Laborit, J. M. Jouany, J. G e r a r d and P. Fabiani, P r e s s e Med. 68, 1867 (1960). 1216 (1961). (42) G. Laborit, A. Kind and C. d e L. Regil, Presse Med. (43) A. B. Drakontides, J. A. Schneider and W. H. F u n d e r b u r k , J. P h a r m a c o l . Exp. T h e r a p . 135, 275 (1965). (44) E. H. Jenny, H. B. M u r p h r e e , L. Goldstein and C. C. Pfeiffer, P h a r m a c o l o g i s t 4, 166 (1962). (45) M. J. HOsko, Jr. and M. I. Gluckman, P h a r m a c o l o g i s t ? , 254 (1963). (46) S . P. B e s s m a n and S . J. Skolnick, Science E,1045 (1964). (47) W. D. W i n t e r s and C. F.Spooner, Intern. J. Neuropharmacol. 4, 197 (1965). (48) B. W. Gunner, G. A. H a r r i s o n , W. D. W a l k e r and I. S. Jenkinson, (11), 327 (1965). Med. J. A u s t r a l i a (49) H. Eisterer, G. F r a u n d o r f e r , P. F o r g e s , H. Seidl and K. Stein638 (1965). b e r e i t h n e r , Wien. Med. Wochschr. (50) J. C. Hewitt, R. C. Hamilton, J. F. O’Donnell and J. W. Dundee, B r i t . J. A n a e s t h e s i a 2 , 115 (1966). (51) c. D. Lunsford, A. D. Cale, J r . , J. W. Ward, B. V. F r a n k o and H. Jenkins, J. Med. Chem. 7 ‘ , 302 (1964). (52) W. E v e r s , K. Malik and A. B. Dobkin, Canad. Anaesth. SOC. J. l2, 281 (1965). (53) A. L. Mauro, L. Labartino, E . Mojdehi and B. Reynolds, Am. J. Med. Sci. 269 (1965).

c,

3,

u,

z,

Chap. 3

Depressants

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39 -

References

(54) F. W. Noe, N. B o r r i l l o and F. E. Greifenstein, A n e s t h e s i a Analgesia, C u r r e n t R e s . 44, 206 (1965). (55) J. s. Israel, G. T. J a n s e n and A. B. Dobkin, Anesthesiology 26, 253 (1965). (56) G. C o r s s e n , P. Chodoff, E. F. Domino and D. R. Kahn, J. T h o r a c . 901 (1965). Cardiov. Surg. 2, (57) J. DeCastro, P. Mundeleer and T. Bauduin, S u r v e y of A n e s t h e s i ology (3, 348 (1965). (58) C. W . Gorodetzky and W. R. Martin, Clin. P h a r m a c o l . T h e r a p . 6, 731 (1965). (59) U. Aubry, R. Denis, M. Keeri-Szanto and M. P a r e n t , Canad. Anaesth. SOC. J. l2, 510 (1965). (60) M. G e m p e r l e and J. C. Buhler, Schweiz. Med. Wochschr. 158 (1965). (61) A. B. Dobkin and P . K . Y . Lee, Canad. Anaesth. SOC. J. l2, 34 (1965). (62) A. B. Dobkin, P . K . Y . L e e and P. H. Byles, Canad. Anaesth. SOC. JI, 39 (1965). (63) P. Chodoff and E . F . Domino, A n e s t h e s i a Analgesia 44, 558 (1965) (64) J. Canellas, J. Roquebert and P. Courtois, Compt. Rend. SOC. Biol. 159 1538 (1965). (65) J. Yelnosky and W. E. Field, Am. J. V e t . R e s . 25, 1751 (1964). (66) I. I. F r a n k l i n and J. S. Reid, V e t . Med. / S m a l l Animal Clinician 60, 927 (1965). (67) J. M o r t e l m a n s , R. M a r s b o o m and J. V e r c r u y s s e e , Bull. SOC. Roy. 2001. d ' A n v e r s 36, 13 (1965). (68) N. W. Shephard, Ed., "The Application of Neuroleptanalgesia in Anesthetic and O t h e r Practice", P e r g a m o n Press, Oxford, 1965. (69) J. R. B o i s s i e r , P. Simon and J. Fichelle-Pagny, TherapieAO, 401 (1965). I

s,

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-J

Sect. I

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- CNS Agents

B i e l , Ed.

Chapter 4. A n a l g e t i c s --Stronf and Weak Louis S . H a r r i s , U n i v e r s i t y of North Carol na, Chapel H i l l , N.C. Introduction The p a s t few y e a r s have witnessed a ferment i n t h e f i e l d of a n a l g e t i c s . S e r i o u s q u e s t i o n s have a r i s e n t o challenge o u r concept of p a i n as a s p e c i a l i z e d sensory system. Indeed we now take a more A r i s t o t e l i a n view of p a i n and speak of t h e " p a i n experience" which encompasses n o t o n l y t h e s e n s a t i o n of p a i n but a s s o c i a t e d s e n s a t i o n s such as touch and h e a t and f e e l i n g s t a t e s such a s f e a r and p l e a s u r e . I t i s n o t s u r p r i s i n g t h e n t h a t more and more drugs a r e becoming a v a i l a b l e f o r t h e t r e a t m e n t of p a i n which appear t o have mechanisms which d i f f e r , sometimes q u i t e markedly, from those of t h e c l a s s i c a l a g e n t s . We now have s t r o n g a n a l g e s i c s which a r e devoid of morphine-like a d d i c t i o n p o t e n t i a l and mild a n a l g e s i c s which a r e i n c r e a s i n g i n t h e i r p a i n r e l i e v i n g potency. I t would appear t h a t we a r e approaching c l s e r and c l o s e r t o t h e i d e a l a n a l g e s i c agent. A r e c e n t monograph P p r e s e n t s an e x c e l l e n t summary of much of t h i s work.

I.

Strong Analgesics Morphine and Morphinans There was l i t t l e a c t i v i t y i n t h i s a r e a i n 1965. P i r k l e and Gates2 prepared t h e hydroaromatic analogs ( I and 11) of t h e p o t e n t a n a l g e s i c s &-3-hydroxy-N-methylmorphinan and t h e c o r r e s ponding isomorphinan. The morphinan ( I ) w i t h a c i s - r i n g f u s i o n was e s s e n t i a l l y i n a c t i v e while t h e isomorphinan pronethalol > MJ 1999.

.

2. Catecholamine Depletors It follows that since beta adrenergic blocking agents are able to antagonize certain types of arrhythmias that catecholaminedepletion might also afford protection against some arrhythmias. In 1963 Roberts et al.17 reported that following reserpinization the ability of digitalis to induce ventricular arrhythmias was diminished. Moreover, $TM 10, an agent which prevents the release of catecholamines, markedly reduced the response of the ventricular pacemaker to digitalis. The abilit of reserpine to antagonize but it should be noted arrhythmias has been confirmed by several workers,al'* that the degree of success is much higher if an adrenalectomized preparation is employed so as to reduce the circulating catecholamines. In addition, guanethidine and bretylium have been reported to antagonize the arrhythmias pro21 duced by acetylcholine and electrical stimulation

-

.'"

3 . Sympathomimtic and Pressor Agents. Certain types of arrhythmias (especially

supraventricular tachycardias) may be converted to normal sinus rhythm by raising the blood pressure, thereby eliciting reflex vagal stimulation. E l l i s a2 has reported that metho-ne and some closely related substituted phenylisopropylamines can effectively convert ventricular tachycardias to sinus m h m . Special mention was made of a-methyl-$-hydroxy-$-( 2,5 diethoxyphenyl)-N-isopropyl ethylamine, which was found to be effective in restoring sinus rhythm under a number of experimentally produced ventricular tachycardias (e .g ouabain, epinephrine with or without hydrocarbon anesthesia, DMPP and coronary artery ligation). Similarly, isopropyl methoxamine has been found to be effective in converting digitalis-induced ventricular tachycardia to sinus rhythm, though the duration was rather transient.'' In their review on the use of vasopressor d r u g s in the therapy of cardiac arrhythmias, Corday and co-workerg4note that in addition

.

88

Sect. I1

- Pharmacodynamics

A r c h e r , Ed.

to methoxmuine, such agents as norepinephrine, mephentermine, m e t a r a m l , phenylephrine and angiotensin have been used successAiLly. However, such therapy is only u s e m when the arrhythmia is associated wlth hypotension. A possible exception lies in the usage of angiotensin which has been found to protect against a variety of experimentally induced arrhythmias both in vitro and in vivo ?,' aeAccordingly, these investigators also ascribed a "quinidine-like" action to angiotensin. In the presence of heart block, ventricular tachycardia and quinidine The mechanism inintoxication, isoproterenol has been used success~ully.~~ volved is apparently based on the fact that isoproterenolaccelerates the basic idioventricular pacemaker thereby suppressing ectopic ventricular activity. The increase in heart rate, coronsry f l o w and cardiac output may also be responsible for terminating arrhythmias. O f course, driving the heart at a more rapid rate could achieve the s8me result as drug therapy. The inherent danger in the use of isoproterenol is that it is almost a pure beta adrenergic stimulator and may precipitate ventricular tachycssdia or fibrillation.a7

4. Local Anesthetics. Since the observation that procaine was effective in suppressing arrhythmias, and the subsequent developnt of procaine amide, numerous local anesthetics psVe been employed in antiarrhythmic drug therapy. Lidocaine, a synthetic local anesthetic, has recently been reported to be of value in the treatment of cardiac arrhythmias.asThe mechanism of action appears to be similar to that of procaine. The conduction time is slowed, excitability depressed and the refractory period prolonged. In therapeutic doses mlyocardial contractility does not appear to be depressed nor is the blood pressure depressed. It ha8 a brief duration, is relatively safe and may be given i.v., all of which may mske it useful in arrhyt,hmias which sometimes occur during cardiac surgery. Pruss and Hidalgo2@have reported on a new substance kvoxadrol!, which is a local anesthetic and a ganglionic blocking agent. The authors claim that it is slightly less potent than quinidine but more potent than either procaine amide or lidocaine in reversing atrial fibrillation caused by the topical application of acetylcholine. Moreover, it is very effective in restoring sinus rhythm in dogs with coronary artery ligation ventricular arrhythmias.

5. htihistaminics. In 1948 it was demonstrated that a number of antihistamines possessed sane pharmacologic properties in common with atropine, procaine amide and quinidine. By 1952 the suppression of ventricular premature

systoles by antazoline had been described, and in 1959 a report appeared noting that antazoline was more effective than quinidine in the suppression of spontaneous and surgically induced ventricular fibrillation in the hypothermic dog?' In conrmDn with quinidine, antazoline is a local anesthetic, possesses sane anticholinergic properties and causes mild adrenergic blockade. However, as opposed to quinidine, It increases peripheral vascular resistance but decreases both stroke volume and cardiac output without altering mean blood pressure. Thus, pressor agents are never required?* Like quinidine it produces its antiarrhythmic effects primarily by depressing conduction velocity. Apparently it is effective in atrial, nodal and

Chap. 8B

Antiarrhythmics

T anz

89 -

ventricular tachycardias, as well as arrhythmias associated with d i g i t a l i s intoxication. Diphenhydramine has also proven t o be an effective31antif l b r i l l a t o r y agent at low doses both i n the laboratory and c l i n i c .

6. Central Nervous System (CNS) Agents. Diphenylhydantoin (Dilantifl) is a potent antiepileptic which produces generalized depression of the CNS. It has been used successfldly i n abolishing numerous arrhythmias both i n the laboratory and i n the c l i n i c ?1 j a 4 * 7 Its duration of action i s however, relatively short (2 30 mins .) I n the heart Dilantin i s said t o diminish conduction velocity, may depress c o n t r a c t i l i t y and produces a net efflux of i n t r a c e u u l a r sodium and an influx of potassium, which tends t o r a i s e the resting membrane potential thereby reducing the likelihood of cardiac arrhythmias. The general impression i s that it should not be used as an antiarrhythmic u n t i l procaine amide and quinidine have been tried f i r s t .

-

.

38

Fekete and Borsy have shown that certain thymoleptics, such as imipramine, desmethylimipramine, amitriptyline and trimepropimine display mild antiarrhythmic a c t i v i t y i n rats and dogs.

7. Miscellaneous Agents. Space limitations preclude the inclusion of the

numerous substances that have been tested for antiarrhythmic a c t i v i t y . The antimalarial substance chloroquine, depresses myocardial e x c i t a b i l i t y and exerts a n t i f i b r i l l a t o r y a c t i v i t y as does the o r a l hypoglycemic phenformin (DBfl).33 Sparteine is a potent, short acting a n t i f i b r i l l a t o r y substance which, i n contrast t o quinidine, increases myocardial conduction velocity. 33 Much i n t e r e s t has been generated i n the antiarrhythmic properties of synthetic oxytocin (Syntocino#) especially by Canadian workers. Syntocinon has been demonstrated t o suppress a variety of laboratory and c l i n i c a l srrythmias, including those related t o catecholamines as w e l l as arrhythmlas induced by injecting metrazol into the fourth ventricle. 39-43 It should be noted however, that 0.55 chlorobutanol is used i n the vehicle and that it a l s o displays antiarrhythmic a c t i v i t y (un ublished observations). The cholinergic drug edrophonium chloride (Tensilo& has been reported t o display transient antiarrhythmic a c t i v i t y , eliminating paroxysmal auricuLar tachycardia i n about 505 of treated patients .a4 Russian workers have recently described the use of cocarboxylase as being effective against a variety of c l i n i c a l l y observed arrthythmias .45 Iproveratril (Isoptin@) i s a new beta adrenergic blocker that has been claimed t o possess antiarrhythmic a c t i v i t y greater than e i t h e r pronethalol or MJ l ~ f ~ ~ 4 7 H o w e v it e r i, s also a toxic substance with a ra.t;her n a r r o w margin of safety. Chelating agents, such as EUI!A, have been employed with various degrees of success i n the past. A new substance in t h i s group i s 10-phenanthroline which was reported t o be as effective as quinidine i n reversing auricular f i b r i l l a t i o n of isolated rabbit hearts. Apparently it accomplishes t h i s by lengthening the refractory period and the depolarization p e r i ~ d f * r ~ ~ Newer chemicalmieties which have been reported t o possess antiarrhythmic activity, but which cannot be c r i t i c a l l y evaluated a t t h i s t i m e , are:

90 -

Sect. I1

-

Pharmacodynamics

A r c h e r , Ed.

,

a s e r i e s of N,N-diisopropyl-N' -isoamyl-N' -diethylaminourea (P-286)s0 N-(~aminoalkyl)phthalimidese~ *5 the procaine amide analogs of p-&no-N[2-( substituted amino) ethyl) benzamides,66 derivatives of morphanthridineB7 2-diethylmino-l-phenylethy1, 2-ethoxy HC1 and i t s 4-ethoxy analoff*, and the l o c a l anesthetic N,N-bis (phenykarbamoyl-nethyl) dimethylaamnium C 1 (QX$ 7 ~ ? ) ' ~More . work w i l l have t o be done on these substances before a fair pharmacologic appraisal can be made.

,

,

References 1. b e , R. A. and Abrams, W. B.: i n "Cardiovasculaz Drug Therapy", ed. A. N. w e s t and J. H. Moyer, G r u n e and Stratton, I?. Y. p.455 (1965). 97 ( 1 9 ~ 1 2. E r l i j , D. and Mendez, R.: J. m c o l . , 21, 462 (1963). 3. Selciya, A. and E. M. Vaughan W i l l i a m s : 4. Wyte, S. R. and R. E. Tan Eick: Fed. Proc., 5. Lucchesi, B. R.: J. Pharmacol., 6. Stickney, J. L., B. R. Lucchesi and G, D. Abrams : Fed. Proc a , 6 2 1 (1966.. 7. Lucchesi, B. R., L. S. Whitsitt and J. L. Stickney: Confr. on New Adrenergic Blocking Drugs; N. Y. Acad. Sci., Feb. 24-26, 1966. 8. Benfey, B. G. : Fed. Proc 24, 234, (1965) 9. Benfey, B. G. and D. R. Varma: Brit. J. P h w c o l . , 26, 3 (1966) 10. Rowlands, D. J,, G. Howitt and P, Ihrkman: Brit. Med. J., 1,891 (1965) ll. Sloman, G., J. S. Robinson and K. Mchan: B r i t . Med. J., 1, 895 (1965). 12. G i l l , E. W. and E. M. Vaughan W i l l i a m s : Nature, 201, 199 T1964) 13. Wallace, A . G., W. G. Troyer, M, A. Lesage and Zotti: 140 (1965) 14. Somani, P. and B. K. B. Lua: J. Pharmacol., 147, 194 (1964). Fed. Proc., &, 712 (1965). 15 Somani, P. and B. K. B. h: 16. Somani, P., J. G. Fleming, G, K. Chan and B. K. B. Lum: J. Phe;rmacol., 151, 32 (1966) 149 (1963). 17. Roberts, J., R . Ho, J. Reilly and V. J. Cairoli: Circ. Res., 325 (1964) 18. Lu, G. G.: Fed. Proc. 19 Ievitt, B., F. Ciofalo and J. Roberts: Fed. 20. Leveque, P. E. and R. C. Grubbs: Fed. Proc. M.: ~ m .J. cardioi., 21. -caner, (1964). 22. E l l i s , C H. : Arch. i n t Phamcodyn., JJO, 23 Paradise, R. R. and V. K. Stoelting: Proc. SOC. Exp , Biol. Med., U6,72 (1964) 24. Corday, E., F. F. Barbieri and T-W. lang: i n Cardiovascular Drug Therapy, ed. A. N. Brest and J. H. Moyer, Grune and Stratton, N. Y., p. 485, 1965. 25 8 Beltrami, E. and A. Beaulnes: Rev. Can. B i o l . , a , 191 (1964). 121 (196; Beaulnes, A., G. Gariepy, J. Brodeur and E. Beltrami : Fed. Proc 25 26. Dreifus, L. S., M. D. Rabbino and Y. Watanabe: i n Cardiovascular Drug Them y, ed. A. N. Brest and J. H. Moyer, G r u n e and Stratton, N. Y., p.491,

144,

145,

.

.,

0

E. x., 18,

a,

a,

.

.

IJ,=~

h.4

a,

0

(196523. . - _ _ 27. Dresel, P. E., M. 28. 29

30 31 32

.

140, 67

C Hart and B. C Stromblad: J. Pharmcol., Frieden, J. : Am. H e a r t J., 713 (1965). pruss, T. P. and J. Hidalgo: Fed. Proc., 32'7 (1964). Angelakos, E. T. and A. R. Hegnauer : J. Pharmacol., 12, 37 (1959) Dreifus, L. S., M. D. Rabbino and Y. batanabe: Med. m n . N. Amer., 371 (1964). Bellet, S : B r i t . Pract 19 (1961).

.

s,

., 186,

a,

(1963).

. 48,

Chap. 8B

Tanz

Antiarrhythmic s

x,

33 34 35 36

9

37 38 39

91 ,-

Lamla, M.: Arch. int. Pharmacodyn., 442 (1965). Mixter, C. G., J. M. &ran and W. Austen: Am. J. Cardiol., 332 (1966). Ruthen, G. C.: Am. Heart Jln., 70, 275 (&). Bernstein, H., H. Gold, T-W. Law, S. Pappelbaum, V. Bazika and E. Corday: JAA-A., 695 (1965)Conn, R. D.: New Engl. J. Med., 2J2, 277 (1965). Fekete, M. and J. Borsy: _Med. exp. l0, 93 (1964). Klassen, G. A.,J. W. Rubin and M. McGregor: Am. J. Cardiol., l2, 523 (1963). Varma, D. R., K. I . Melville and M. D. S i l v e r : Arch. i n t . Pharmacodyn., 4-40(1963). M e l v i l l e , K. I. and D. R. Varma: Biochem. Pharmacol., 8, 136 (1961). Panesset, J. C. and A. Baulnes: Rv. Can. Biol., 20, 47-(1961).

x,

a,

40.

41.

.

42.

43 Bircher, R. P. : Fed. Proc 3, 560 (1964). 44. Moss, A. J. and L. M. Aledort: Am. J. Cardiol., JJ, 62 (1966). 45 Bakumenka, M. S.: Kardioloaiya (U.S.S .R.), abstracted i n Excerpta Med. 2, 1965. 46. Melville, K. I., Shister, H. E. and S. Huq: C a n . Med- Jln., g,761 (1964). 47. Schmid, J. R . and C. Hanna: Fed. Proc., 3, 382 (1966). 48. Yaw, W. C., S. Rothman and A. Gimeno: Proc. SOC. EXP Biol. Med., 2, 136 (1963). 49 Rothmsn, S. and W. C. Yaw: Am. J. Physiol., 206, 283 (1964) 50 Garrett, J., M. Goncalves Moreira, W. Osswald and S. GUimaraeS: 9

s.,

.

143,

51 52

53

54. 55

-

56 57

.,

J. Pharmacol., 243 (1964). Kempen, R. R . : Fed. Proc 3, 327 (1964). Hideg, K and H. 0. Hankovszky: Acta Chima. Acad. Sci. Hun@;., 3, 391 (1963) Hideg, K., L. Szekeres, H. 0. Hankovszky and J. Pam: Biochem. pharnaacol. (Suppl.), 12, 171 (1963). Hideg, K. and H. 0. Hankovszky: J. Med. Chem., 8 257 (1965). Szekeres, L., K. Hideg, H. 0. Hankovoszky and G. Papp: Acta phxsiol. Hung., 26, 287 (1965). Thyrum, P and A . R. Day: J. Med. Chem., 107 (1965) Werner, L. H., S . Ricca, E. Mohacsi, A , Rossi and V. P o Arya: J. Med. Chem.,

6

-8 74 (1965). 58. Grelak, R. P. and T. R. Sherrod: Fed. Proc. 24, 234,(1965). 59 Covino, B. G. and P. Rachwell: J. New Dru@;6 , Jan-Feb., 30 (1964). 0

92 -

Sect. I1 Chapter 9 .

- Pharmacodynamics

A r c h e r, Ed.

Pulmonary and A n t i a l l e r g y Agents.

Walter T. Moreland, Chas. P f i z e r ti Company, Inc.,

Groton, Conn.

Medicinal chemical p r o g r e s s i n t h e f i e l d s of pulmonary and a n t i a l l e r g y a g e n t s * h a s been slow i n r e c e n t y e a r s . A t least t h r e e f a c t o r s a p p e a r t o have been r e s p o n s i b l e , i n v a r y i n g d e g r e e s , f o r t h i s h i a t u s : ( 1 ) t h e r e have been r e l a t i v e l y few advances i n i n s i g h t i n t o t h e n a t u r e of u n d e r l y i n g mechanisms, SO t h a t s c r e e n i n g methods have tended t o remain u n s p e c i f i c o r i n a p p r o p r i a t e ; ( 2 ) t h e p u r s u i t of e x i s t i n g s t r u c t u r a l l e a d s h a s f a i l e d t o p r o v i d e a g e n t s s u p e r i o r to t h o s e a l r e a d y i n u s e ; and ( 3 ) i n some i n s t a n c e s t h e r e h a s n o t been a n obvious need t o improve upon e x i s t i n g d r u g s , e s p e c i a l l y i n t h e f a c e of more u r g e n t probl e m s i n o t h e r areas, which h a s tended to d i s c o u r a g e s p e c i f i c r e s e a r c h c a l c u l a t e d t o produce new l e a d s and new methodology. R e t r o s p e c t i v e l y , t h i s p a t t e r n was s u b s t a n t i a l l y unchanged i n 1965, and a d e q u a t e summaries of c u r r e n t s t a t u s are provided i n a p p r o p r i a t e s e c t i o n s of newly r e v i s e d e d i t i o n s of s t a n d a r d reference t e x t s. 192 The f i e l d of pulmonary a g e n t s seems c e r t a i n t o become c o n s i d e r a b l y more a c t i v e i n t h e f u t u r e , however, i n t h e l i g h t of c l i n i c a l developments t h a t have r e c e i v e d widespread a t t e n t i o n i n 1965. The N a t i o n a l Heart I n s t i t u t e , i n a r e p o r t t o t h e S e n a t e A p p r o p r i a t i o n s Subcommittee,3 s t a t e d t h a t "emphysema h a s mushroomed i n t o a major h e a l t h problem, seemingly o v e r n i g h t d i s a b i l i t y benef i t s f o r emphysema are (now) exceeded o n l y by d i s a b i l i t y b e n e f i t s f o r a t h e r o s c l e r o s i s and coronary h e a r t d i s e a s e . 'I Many c l i n i c a l d i s c u s s i o n s of c h r o n i c o b s t r u c t i v e lung d i s e a s e p r e s e n t e d similar c o n c l u s i o n s .4 I n s p e c t i o n of t h e a g e n t s p r e s e n t l y a v a i l a b l e t o t h e p h y s i c i a n shows t h e l i s t 5 t o be dominated by sympathomimetic and x a n t h i n e b r o n c h o d i l a t o r s , e x p e c t o r a n t s and mucolytic a g e n t s and none of t h e s e i s p a r t i c u l a r l y new. ( C e r t a i n r e s p i r a t o r y s t i m u l a n t s 3 , 6 and a n t i i n f l a m a t o r y a g e n t s 3 are a l s o r e p o r t e d , b u t t h e i r u s e i s n o t u n i v e r s a l l y f a v o r e d . 4 ~ 7 ) The e n t i r e f i e l d was t h o r o u g h l y reviewed by Aviado i n two volumes c i t i n g ' s e v e r a l thousand r e f e r e n c e s . 8 It i s clear t h a t t h e r e i s room f o r improvement i n a l l classes, and i t may be e x p e c t e d t h a t o t h e r approaches t o complement o r d i s p l a c e t h o s e i n c u r r e n t use w i l l emerge as r e s e a r c h i n t e r e s t i n c r e a s e s .

...

****** *For t h e purpose of t h i s review, t h e c a t e g o r y "pulmonary and a n t i a l l e r g y a g e n t s " is c o n s i d e r e d t o i n c l u d e b r o n c h o d i l a t o r s , a n t i t u s s i v e s , e x p e c t o r a n t s , m u c o l y t i c s , n a s a l d e c o n g e s t a n t s and a n t i p r u r i t i c s ( a n t i h i s t a m i n e s ) . A n t i b i o t i c s , which occupy a n important t h e r a p e u t i c p o s i t i o n i n t h e r e s p i r a t o r y area, and a n t i i n f l a m m a t o r y a g e n t s are excluded because they u s u a l l y would n o t be developed s p e c i f i c a l l y f o r these indications (although antiinflammatory s t e r o i d s d e s i g n e d f o r t o p i c a l u s e might c o n s t i t u t e a n i m p o r t a n t e x c e p t i o n ) . D e s e n s i t i z a t i o n p r o c e d u r e s are c o n s i d e r e d t o be o u t s i d e t h e scope of medicinal chemistry.

Chap. 9

Mo reland

Pulmonary, Antiallergy

93 -

There can be l i t t l e doubt t h a t b r o n c h o d i l a t i o n by sympathom i m e t i c a g e n t s i s mediated through p - r e c e p t o r s , so t h a t i t i s n o t s u r p r i s i n g t h a t s i d e e f f e c t s such as t a c h y c a r d i a , r e s u l t i n g from e x c e s s i v e s t i m u l a t i o n o f p - r e c e p t o r s a t o t h e r s i t e s , should be a common o c c u r r e n c e . l a , 2a Poor o r e r r a t i c o r a l a b s o r p t i o n o f t e n p r e s e n t s an a d d i t i o n a l problem. I s o p r o t e r e n o l (I) , t h e p r o t o t y p e p-sympathomimetic, dominates !he group. 3Y4 Most o f t h e newer a g e n t s are c l o s e l y r e l a t e d t o i s o p r o t e r e n o l , and a l l are most o f t e n a d m i n i s t e r e d l o c a l l y i n some form o f a e r o s o l t o minimize s i d e e f f e c t s . Two a d d i t i o n a l a n a l o g s , c l o r p r e n a l i n e ( I n 9 and metaprot e r e n o l ( o r c i p r e n a l i n e , 111) ,lo r e c e i v e d c o n s i d e r a b l e c l i n i c a l a t t e n t i o n , e s p e c i a l l y i n Europe. The former i s s u i t a b l e f o r o r a l a d m i n i s t r a t i o n , b u t

I

i t a p p e a r s t o e l i c i t s u f f i c i e n t CNS s t i m u l a t i o n t o r e q u i r e concomitant a d m i n i s t r a t i o n o f a CNS d e p r e s s a n t . The l a t t e r , which i s r e p o r t e d t o have a minimal e f f e c t on h e a r t r a t e , h a s been most o f t e n a d m i n i s t e r e d by a e r o s o l . A v e r y r e c e n t report'' d e s c r i b e d a s e r i e s o f catecholamine a n a l o g s i n which t h e p h e n o l i c hydroxyls a r e r e p l a c e d by a l k y l - o r a r y l sulfonamido s u b s t i t u e n t s o f comparable a c i d i t y . When t h i s s u b s t i t u t i o n i s meta t o t h e ethanolamine s i d e c h a i n , p o t e n t a - o r p - r e c e p t o r s t i m u l a n t s r e s u l t ; t h e most a c t i v e p - a g o n i s t s o f t h e s e r i e s ( I V Y V and VI) approach t h e potency of e p i n e p h r i n e o r i s o p r o t e r e n o l i n smooth muscle p r e p a r a t i o n s . B r o n c h o d i l a t o r s t u d i e s w i t h t h e s e a n a l o g s have n o t been r e p o r t e d , and l i t t l e can be d i s c e r n e d from p r e s e n t e v i d e n c e r e g a r d i n g s p e c i f i c i t y o f a c t i o n . I n t e r e s t i n g l y , comparable s u b s t i t u t i o n i n t h e para p o s i t i o n

R1 IV V

R2

H

H

OH

H

VI a f f o r d s predominantly p-blocking a g e n t s . The problem o f s p e c i f i c i t y of a c t i o n among $-sympathomimetics remains a s u b s t a n t i a l c h a l l e n g e , which many would a r g u e t o be e s s e n t i a l l y u n r e s o l v a b l e because of t h e wide a n a t o m i c a l d i s t r i b u t i o n o f p - r e c e p t o r s . However, t h e work o f Lands and Brown," showing t h a t a - e t h y l s u b s t i t u t i o n i n c e r t a i n 6 - a g o n i s t s markedly f a v o r s p - r e c e p t o r s i n t h e b r o n c h i o l e s o v e r t h o s e i n t h e h e a r t ( T a b l e I ) , s u g g e s t s t h a t d i f f e r e n t i a t i o n among p - r e c e p t o r s i s p o s s i b l e and that c a r e f u l s t u d y may r e v e a l c o n s i d e r a b l e o p p o r t u n i t y t o achieve s p e c i f i c i t y f o r a particular site.

Sect. I1

94 -

- Pharmacodynamics

A r c h e r , Ed.

Table I E f f e c t of a - E t h y l S u b s t i t u t i o n on t h e S e c i f i c i t y o f A c t i o n o f P2 Sympat homime t i c A m i ne s

Rl -

H C2H5 H C2H5

R2 isopropyl isopropyl cyc l o pent y 1 cyclopentyl

R e l a t i v e P o t e n c i e s ( I s o p r o t e r e n o l = 1) +Cb Bronchodi l a t i o n +Ia -

1 0.06 .6

.016

1 0.001 .6 .0005

1 0.33

.7

.45

(a) positive inotropic effect (b) positive chronotropic e f f e c t Over tbe y e a r s , a c o n s i d e r a b l e number of x a n t h i n e a n a l o g s and d e r i v a t i v e s have been s t u d i e d . However, none h a s y e t succeeded i n d i s p l a c i n g t h e o p h y l l i n e , which remains t h e predominant non-sympathomimetic bronchol b , 21 d i l a t ~ r , ~ i n- s~p i t e of s u b s t a n t i a l o r a l a b s o r p t i o n and s i d e e f f e c t problems. Because of t h e a p p a r e n t s t r u c t u r a l and pharmacological l i m i t a t i o n s i n h e r e n t i n t h e sympathomimetic approach, t h e f u t u r e seems c e r t a i n t o b r i n g a s u b s t a n t i a l i n c r e a s e i n e f f o r t s t o d e v e l o p a g e n t s more c l o s e l y r e l a t e d t o t h e x a n t h i n e s . A novel workin h y p o t h e s i s , which d e r i v e s from t h e e l e g a n t work of S u t h e r l a n d and h i s g r o u p Y f 3 o f f e r s a p o s s i b l e new approach t o t h e development o f improved a g e n t s i n t h i s class. Although t h e r e i s some evidence t h a t i s not e n t i r e l y c o n s i s t e n t , l b t h e h y p o t h e s i s s u g g e s t s t h a t t h e b r o n c h o d i l a t o r a c t i o n of theop h y l l i n e i s t h e r e s u l t o f i n c r e a s e d l e v e l s of c y c l i c 3',5-AMP brought about by p h o s p h o d i e s t e r a s e i n h i b i t i o n . T h i s would d i r e c t l y r e l a t e t h e o p h y l l i n e t o p - r e c e p t o r s , where c y c l i c 3 ' ,5'-AMP s y n t h e s i s i s thought t o be i n c r e a s e d through s t i m u l a t i o n of a d e n y l c y c l a s e by a p p r o p r i a t e a g o n i s t s . There i s y e t l i t t l e d i r e c t e v i d e n c e , however, t o s u g g e s t t h a t t h i s i s t h e o n l y , o r even t h e major, m e c h a n i s t i c component o f t h e o p h y l l i n e b r o n c h o d i l a t i o n , so i t remains t o be determined how f r u i t f u l t h e approach w i l l be. Mucolytic a g e n t s and e x p e c t o r a n t s l C y 2a' r e used t o d e c r e a s e t h e v i s c o s i t y o f , and a i d i n c l e a r i n g b r o n c h i a l s e c r e t i o n s . A number o f a g e n t s are a v a i l a b l e Y 5 i n c l u d i n g many o l d e r p r e p a r a t i o n s such as i o d i d e s and g u a i a c o l a t e s . The more r e c e n t a d d i t i o n s , N - a c e t y l e y s t e i n e , r i b o n u c l e a s e and v a r i o u s p r o t e o l y t i c enzymes, are u s u a l l y a d m i n i s t e r e d l o c a l l y i n a nebul i z e d form. The c l i n i c a l v a l u e o f t h e s e a g e n t s does n o t a p p e a r t o be unanimously acce t e d Y 4and o b j e c t i v e d e m o n s t r a t i o n of e f f i c a c y i s o f t e n d i f f i c u l t t o o b t a i n . l I T h i s s u g g e s t s a decided need f o r more e f f e c t i v e p r o d u c t s , s i n c e t h e r e seems t o be l i t t l e doubt t h a t t h i s i s a v a l u a b l e t h e r a p e u t i c a p p r ~ a c h . ~ , ~

Chap. 9

Mo reland


95 -

Better a g e n t s w i t h l o c a l a c t i o n , designed from chemical knowledge o f s p e c i f i c components i n b r o n c h i a l s e c r e t i o n s , l5 r e p r e s e n t a n obvious avenue o f a t t a c k . The r e p o r t s t h a t p i m e t i n e ( V I I I ) 1 6 and Bisolvon ( I X ) 1 7 reduce sputum v i s c o s i t y a f t e r systemic a d m i n i s t r a t i o n a r e probably of g r e a t e r p o t e n t i a l i n t e r e s t , s i n c e a g e n t s n o t dependent on d e l i v e r y through a i r w a y s t h a t may be s e v e r e l y o b s t r u c t e d would be e x p e c t e d t o have i n h e r e n t advantages.

Br VIII

IX

A n t i t u s s i v e d r u g s l c y Z cwere reviewed by Bucher,18 who c l e a r l y p o i n t e d o u t t h e need f o r more s o p h i s t i c a t e d s c r e e n i n g t o o l s based on a b e t t e r u n d e r s t a n d i n g of t h e cou h r e f l e x . A n t i t u s s i v e a c t i v i t y i n s e v e r a l s t r u c t u r a l t y p e s was r e p o r t e d , f9-25 b u t t h e s e do not a p p e a r t o r e p r e s e n t 26 s u b s t a n t i a l d e p a r t u r e s from t h o s e reviewed e a r l i e r by Chappel and von Seeman. Drug t r e a t m e n t of a l l e r g i c d i s o r d e r s , i f a n t i i n f l a a o r y a g e n t s a r e excluded, i s l i m i t e d almost e x c l u s i v e l y t o antihistamines','d and c e r t a i n sympathomimetic a g e n t s . l a , 2a The l a t t e r class i n c l u d e s b o t h a-mimetics, used as n a s a l d e c o n g e s t a n t s , and p - m i m e t i c s ( d i s c u s s e d a b o v e ) , which are g e n e r a l l y f o r a c u t e use as i n a n a p h y l a c t i c r e a c t i o n s . A new a - m i m e t i c , amidephrine (X) , from t h e s e r i e s of sulfonamido a n a l o g s a l r e a d y 11,2 mentioned, was r e p o r t e d t o be a n e f f e c t i v e and l o n g - a c t i n g n a s a l d e c o n g e s t a n t .

CHCHzNHCH3

I

OH

CH3

X The complexity o f a l l e r g i c phenomena, and t h e need f o r t r u e understanding o f t h e i n t e r p l a y of t h e v a r i o u s c o n t r i b u t i n g f a c t o r s h i s t a m i n e , s e r o t o n i n , k i n i n s and o t h e r s - i s a p p a r e n t i n the m e c h a n i s t i c s t u d i e s 2 8 t h a t c o n t i n u e t o i n v e s t i g a t e v a r i o u s a s p e c t s of h y p e r s e n s i t i v i t y and e s p e c i a l l y i n t h e review o f methods f o r t h e i n d u c t i o n o f e x p e r i m e n t a l h y p e r s e n s i t i v i t y by Spencer and West.29 A symposium c h a i r e d b Ungar e x p l o r e d t h e v a r i e t y of p h y s i o l o g i c a l f u n c t i o n s proposed f o r h i s t a m i n e ," and G a r a t t i n i and V a l z e l l i p r e s e n t e d a n e x t e n s i v e review of ~ e r o t o n i n . ~ ' Cursory reviews o f p r e s e n t a n t i h i s t a m i n e usage32 s e r v e d t o emphasize t h e r e l a t i v e q u i e s c e n c e o f t h e f i e l d i n terms of d r u g development.

96

Sect. I1

- Pharmacodynamics

A r c h e r , Ed.

Various 6-7-6 t r i c y c l i c r i n g systems - s t r u c t u r a l l y t h e most i n t e r e s t i n g class of a n t i h i s t a m i n e s , even though t h e i r impact h a s been f a r g r e a t e r i n o t h e r f i e l d s - continued t o receive a t t e n t i o n . Structurea c t i v i t y s t u d i e s i n dibenzocycloheptene a n a l o g s r e l a t e d t o cyproheptadine were reported.33 Rubin d e s c r i b e d t h e pharmacology of a dibenzoxazepine w i t h 1-10 times t h e potency of p y r i l a ~ n i n e ,and ~ ~ P r o t i v a reviewed r e c e n t I n o t h e r areas, a developments i n s e v e r a l o t h e r , r e l a t e d systems.35 series of t e t r a h y d r o q u i n a z o l i n e s w a s described,36 one of which (XI) was r e p o r t e d t o be comparable t o chlorpheniramine i n t h e c l i n i c . 3 7 CH2CH2N(CH3)2

0

XI References (1)

" D r i l l ' s Pharmacology i n Medicine," 3rd ed., J . R. D i P a l m , Ed., M c G r a w - H i l l Book Company, New York, N. Y . , 1965. ( a ) B. Levy and R. P. A h l q u i s t , Chapter 31; ( b ) E . B. T r u i t t , Chapter 27; ( c ) E. M. Boyd, Chapter 49; ( d ) F. E . Roth and I. I. A. Tabachnick, Chapter 48.

(2)

'The Pharmacological Basis of T h e r a p e u t i c s , ' ' 3rd e d . , L. S. Goodman and A. Gilman, Ed., Macmillan Company, New York, N. Y . , 1965. ( a ) I. R. Innes and M. Nickerson, Chapter 24; ( b ) J . M. R i t c h i e , Chapter 19; ( c > J. H. J a f f e , p. 280; ( d ) W. W. Douglas, C h a p t e r s . 2 9 and 30.

(3)

Anon., Drug Research Reports, 4, No. 34 ( s u p p l . ) , S-2 (August 25, 1965)

(4)

see, f o r example: H. A . Lyons, J . Am. Med. ASSOC., 1 9 4 , 1234 (1965); R. J . Johnston and H. W . Harris, Med. C l i n . N. Am., 49, 1309 ( 1 9 6 5 ) ;

w.,

B. M. Cohen, Geriatrics, 20, 999 ( 1 9 6 5 ) ; F. J . C . M i l l a r d , 20, 854 (1965); R. F. Corpe, S. Grzybowsbi, F . M. MacDonald, M. M. Newman, A. H. Niden, A. B. Organick, and W. Lester, Am. Rev. Respirat. Dis., 92, 513 (1965); R. M . Cherniak, Ann. N. Y. Acad. S c i . , 121,942 (1965). (5)

Anon.

, pharmhdex,

41 ( J a n u a r y 1965).

Chap. 9


P. Sadoul, Ann. N. Y . Acad. S c i . ,

121, 836

Mo reland

97

(1965).

M. E . Bader and R. A. Bader, Am. J. Med., 38, 165 ( 1 9 6 5 ) . D. M. Aviado, 'The Lung C i r c u l a t i o n , " Vole. I and XI, Pergamon P r e s s , New York, N. Y . , 1965.

B. K r a f t and J. G. Armstrong, Appl. Ther.,Z,

829 ( 1 9 6 5 ) .

M. E . Coleman and L. A. Howard, Ann. Alergy, 23, 434 ( 1 9 6 5 ) ; examples from t h e European l i t e r a t u r e i n c l u d e : A. Knopp, Med. Welt., 764 (1965); H. I l l i g , Med. Klin.(Munich), 60, 1452 ( 1 9 6 5 ) ; M. F i s c h e r and U. Mielki, g ,1824 ( 1 9 6 5 ) .

a.,

R. H. Uloth, J . R. K i r k , W. A. Gould, and A. A. L a r s e n , J. Med. Chem., 88 (19661, and r e f e r e n c e s t h e r e i n .

-9 ,

Lands and T. G. Brown, Jr., Proc. SOC. E x p t l . B i o l . Med., 116, cf. D. R. Van Deripe and N. C. Moran, E e d e r a t i o n P r o c . , 24, 712 (1965); B. Levy, J. Pharmacol. E x p t l . Therap., 129 (1964) f o r r e l a t e d observations with p-blocking agents. A. M.

331 (1964);

146,

E . W. S u t h e r l a n d , I. $ye, and R. W . B u t c h e r , Recent P r o g r . Hormone Res 21, 623 (1965)

- - 3

Committee on Drugs of t h e Research C o u n c i l , J. A l l e r g y ,

3,:488

(

1965).

P. L. Masson, J. F . Heremans, and J. P r i g n o t , Biochim. Biophys. Acta, (1965).

111, 466

S. Chodosh, A b s t r a c t s , 6 6 t h Annual Meeting of t h e American T h e r a p e u t i c S o c i e t y , June 1965, p . 29. see f o r example, W . Junge, W. Guenthner, E . Haslreiter, K . Hess, and M. Loos, Med. K l i n . (Munich), @, 2058 (1965); cf. J. Hamm and E . Hunekohl, A r z n e i m i t t e l - F o r s c h . , l6, 209 (1966). K . Bucher i n " P h y s i o l o g i c a l Pharmacology," V o l . 11, W. S . Root and F. G. Hofman, Ed., Academic P r e s s , New York, 1965, p . 175. M. C a r i s s i m i , A . C a t t a n e o , R. D'Ambrosio, V. DePascale, E . G r u m e l l i , E. Milla, and F. Ravenna, J . Med. Chem., 2, 542 ( 1 9 6 5 ) . F . P . Doyle, M. D. Mehta, R. Ward, J . B a i n b r i d g e , and D . M. Brown, 571 ( 1 9 6 5 ) .

m.,2,

S. Casadio, G. P a l a , E . C r e s c e n z i , T . Bruzzese, E . Marazzi-Uberti, -8, 589 (1965). and G. Coppi,

w.,

Sect. I1

98 -

- Pharmacodynamics

A r c h e r , Ed.

#

(22)

J . C. LeDouarec, G. Regnier, and R. C a n e v a r i , A r z n e i m i t t e l - F o r s c h . , 1 5 , 1330 (1965).

(23)

E . M a r c h e t t i , G. Mattalia, and F. Samueli, Farmaco, Ed. S c i . , 696 (1965).

(24)

M. Pesson, S. Dupin, M. Antoine, D . Humbert, and M . J o a n n i c , SOC. Chim. F r a n c e , 2262 ( 1 9 6 5 ) .

(25)

K . Takagi, I. Takayanagi, and M. Imamura, J . Pharm. SOC. J a p a n , 85, 550 (1965).

(26)

C.

(27)

(28)

I . Chappel and C . von Seeman, P r o g r . Med. Chem.,

m.

89 (1963).

H. C. S t a n t o n , K . W. Dungan, and P. M. L i s h , I n t e r n . J . Neuropharmacol., 235 ( 1 9 6 5 ) ; K . W. Dungan, H . C . S t a n t o n , and P . M. L i s h , 4, 219 ( 1 9 6 5 ) .

w.,

4,

T y p i c a l examples are:

209, 545, 550 ( 1 9 6 5 ) ; 13, 189 (1965).

B. M. A l t u r a and B. W. Zweifach, Am. J . P h y s i o l . , G. B. Fregnan and A. H . G l b s e r , Med. E x p t l . ,

P. S . J. Spencer and G. B. West, P r o p r . Med. Chem., G. Ungar, F e d e r a t i o n P r o c . ,

24,

1293ff.

4,

1 (1965).

(1965).

S . G a r a t t i n i and L. V a l z e l l i , " S e r o t o n i n , " N e w York, N . Y . , 1965.

(32)

3,

E,

E l s e v i e r P u b l i s h i n g Company,

R. W. M o r r i s , p h a r m h d e x , 4 ( J a n . 1 9 6 6 ) ; J . D. Horan, Can. Med. Assoc. 93, 1031 (1965).

2-9

(33)

E . L. E n g e l h a r d t , H . C . Z e l l , W. S . S a a r i , M. E . C h r i s t y , C. D . C o l t o n , C. A. S t o n e , J . M. S t a v o r s k i , H. C . Wenger, and C. T . Ludden, J . Med. Chem., 2 , 829 ( 1 9 6 5 ) .

(34)

B. Rubin, J . J . P i a l a , R. M i l l o n i g , and B. N . C r a v e r , Arch. I n t e r n . Pharmacodyn., 155, 47 ( 1 9 6 5 ) .

(35)

M. P r o t i v a , Farmaco, Ed. S c i . ,

(36)

G . Muacevig, H .

(37)

H. J. Lange,

J

(1965).

21,

76 ( 1 9 6 6 ) .

S t B t z e r , and H . Wick, A r z n e i m i t t e l - F o r s c f i . ,

m.,l5, 1411 ( 1 9 6 5 ) .

l5, 613

Chapter 10.

Agents Affecting G a s t r o i n t e s t i n a l Functions

W i l l i a m A. Bolhofer and David A. Brodie, Merck Sharp & Dohme Research Laboratories, West Point, Pa. EXPERIMENTAL INVESTIGATIONS Stimulation of Gastric Secretion

A major advance i n t h e biochemistry of g a s t r i c s e c r e t i o n has the determination of s t r u c t u r e and synthesis of g a s t r i n I and I1 from yarious species. Porcine g a s t r i n I has been shown t o be the heptadecapeptide I. Porcine g a s t r i n I1 (11) has t h e same peptide sequence but with n

RL

1-GluGluGluGluGluAlaTyrGlyTryMetAspPheNH2 I

@GluGlyProTry-R

2

R1 = Met, R = H 1 2 11, R = Met, R = SO H I,

3

111,

R

1

= Leu, R~ = H

IV, R~ = Leu, R~

= SO~H

Both were equipotent t h e tyrosine hydroxyl i n t h e form of i t s s u l f a t e ester.' and showed the same b i o l o g i c a l e f f e c t s . The pure h y n g a s t r i n s have been isol a t e d , 2 and degradative analyses3 and t o t a l synthesis showed t h a t human gast r i n I (111) and human g a s t r i n I1 (IV) w e r e heptadecapeptides i d e n t i c a l t o t h e porcine g a s t r i n s except f o r replacement of one of t h e methionine components by leucine. The porcine g a s t r i n s stimulated s e c r e t i o n i n other species including dogs and man. Elucidation of t h e amino acid sequence of t h e g a s t r i n s permitted an exami n a t i o n of the e f f e c t of s t r u c t u r e modification on the b i o l o g i c a l a c t i v i t y and presented an opportunity f o r the synthesis of i n h i b i t o r y analogs of t h e n a t u r a l The Chormone. A series of peptides r e l a t e d to g a s t r i n I has been t e ~ t e d . ~ terminal t e t r a p e p t i d e (V) was the minimum fragment of t h e g a s t r i n molecule which V,

TryMetAspPheNH2

showed a l l t h e physiological a c t i v i t i e s of t h e n a t u r a l hormone. Based on s t i h u l a t i o n of g a s t r i c acid s e c r e t i o n i n dogs, i t was about 20% as potent as gast r i n . The C-terminal amide was e s s e n t i a l f o r a c t i v i t y , whereas acylation of t h e N-terminal amino group had l i t t l e e f f e c t on t h e a c t i v i t y . The e f f e c t on a c t i v i t y o f a numb r of s t r u c t u r a l modifications of the t e t r a p e p t i d e (V) has been determined.' The v a r i a t i o n s i n t h e main group of analogs studied consisted of s i n g l e or multiple s u b s t i t u t i o n of one or more of the amino acid residues, including replacement o f the normal L amino acids by D amino acids. Activity of products with respect t o g a s t r i c s e c r e t i o n i n dogs varied from equipotent with g a s t r i n f o r c e r t a i n acylated d e r i v a t i v e s (VI, VII)

100 -

Sect. 11. - Pharmacodynamics VI9

A r c h e r , Ed.

H2NCOTryMetAspPheNH2

VII, (CH3) 3COCD.&AlaTryMetAspPheNH2 to inactive for those peptides not having a terminal amide group. In addition, the effect of some of the analogs on other physiological functions such as gastric motility was not uniformly consistent with the direction of the effect on gastric secretion, thus indicating a separation of the various gastrin activities. The presence of D amino acids gave peptides of decreased activity, and none of these products, including the inactive all D tetrapeptide, inhibited the action of gastrin. It was concluded that the most important structural feature of the tetrapeptide for activity was the aspartic carboxyl-terminal amide combination.

In humans, gastrin was 80-fold more potent than histamine in stimulating ~ecretion.~At present, the major clinical use of gastrin or active fragments thereof would appear to be for the replacement of histamine and other secretagogues for diagnostic analysis of gastric secretion^.^" Gastrin appeared to exert a stimulatory and inhibitory effect on acid secretion, at l o w and high doses, respectively, and a stimulatory effect on pepsin secretion at high doses regardless of whether the initial stimulation was histamine or However, it has been suggested that timulation was the normal effect and inhibition was the result of overdosage.” The histamine content of the stomach mucosa was decreased by astrin, indicating that it may act as a secretory agent by releasing histamine.f2 Acid secretion stimulated b exogenous gastrin was inhibited by heparin13 and by insulin hypoglycemia. ll Gastrin I1 has been shown o increase oxygen consumption and cause vasodilation in the stomach m u c o ~ a . ~It~ also caused a pronounced increase in gastrointestinal motility which was inhibited by atropine.16 Gastrin I and I1 were approximately 20-fold more active than histamine for the stimulation of intrinsic factor secretion by the human ~tomach.~ 2-Deox~glucose: Study of acid secretion stimulated by 2-deoxyglucose indicated that it functions by foming nonmetabolizable 2-deoxyglucose-6-phosphate, resulting in cytoglucopenia at the vagal secretory center. Thus, in effect, this mechanism of stimulation of gastric secretion was apparently equivalent to the hypoglycemic mechanism of stimulation resulting from insulin administration. It has recently been shown that, after insulin stimulation, the increase in f l o w of gastric contents occurred simultaneously with or followed the lowest point reached by the blood sugar. l8 Since the central regulatory mechanism for gastric secretion acts through the vagus nerve, stimulation of the secretory center by insulin is a method which has been used to study the completeness of vagotomy in the surgical treatment of peptic ulcer. Tests in humans showed that 2-deoxyglucose produced the same hypersecretion as insulin without the attendant side effects. Therefore, it has been suggested that insulin be re laced by 2-deoxyglucose for evaluation of patients who have undergone vagotomy. P9

Chap. 10

Gastrointestinal

Bolhofer and Brodie

101 -

Histamine: Numerous studies devoted to the evaluation of the role of histamine in stimulating gastric secretion have been reported. All results indicated that histamine is the chemical mediator of gastric secretion c m o n to all stimulants. Inhibition of specific histidine decarboxylase by the hydrazino analog of histidine and NSD-1055 4-bromo-3-hydroxybenzyloxyamine), agents which lower tissue histamine levels,‘O in pylorus-esophagus-ligated rats prevented stimulation of acid secretion by reserpine, bethanechol chloride (2-carbamoylpropyltrimethylanrmonium chloride), insulin and gastrin, but not exogenous histamine. These results showed hat acid secretion was dependent on the presence of histamine in the mucosa.“ It has also been shown that vagal stimulation led to mobilization of gastric histamine.22 Gastric secretagogues, such as gastrin, insulin, betazole &(&aminoethyl)pyrazola and bethanechol chloride, lowered gastric tissue histamine levels, but it was not luiown if their stimulatory effect on secretion was a consequence of gastric histamine release. However, the enzyme histaminase prevented gastric acid secretion in dogs under the stimulating effect of a gastrin extract.23 Portacaval shunt, which in man results in an increased incidence of duodenal ulcer, in rats caused an increase in acid secretion. Als6, histidine decarboxylase activity in the fundus, the acid-secreting portion of the stomach, has been shown to undergo a 4-fold increase after this operation. The elevated acid secretion was reduced essentially to normal by treatment with NSD-1055, the previously mentioned inhibitor of histidine decarboxylase. 24 Inhibition of Gastric Secretion Benzothiazoles: Antisecretory activity in a series of 3-amincr2,l-benzisothiazoles (VIII), determined by measuring gastric volume reduction after

VIII,

c , ” > s R 1/

\R2

f

subcutaneous administration to pylorus-li ated rats, varied from an ED50 of 1.5 mg./kg. to greater than 50 mg./kg. R and R2 consist of hydrogen, lower alkyl and phenyl, and some members of the series were also substituted in the benzenoid ring. Representative examples from the series did not show anticholinergic activity.25 Anticholinergics: The effects of anticholinergic agents on gastric acid secretion were compared with pharmacological effects on gastric emptying and pupil diameter, and it was concluded that the relationship of the secondary actions to the desired action’ofgastric acid inhibition was more important in evaluation than the absolute potency. 26 Experimental Ulcer Production The major objectives of the examination in laboratory animals of agents which produced gastrointestinal irritation or ulceration have been the discovery of preventative or counteracting agents and elucidation of the mechanism

102

Sect. I1 - Pharmacodynamics

A r c h e r , Ed.

of ulceration. The ulcerative action of serotonin was significantly diminished by administration of the antiserotonin methysergide (Deseril; 1-methyl-Dlysergic acid butanolamide tartrate) .29, 2g Antienzymes of pancreatic origin (Kunitz inhibitor) 29 or parotid origin (Frey inhibitor)3O markedly reduced the number of lesions resulting from reserpine or phenylbutazone. Aspirin damage to the intestinal mucosa occurred regard1 ss of whether It has been contact with the drug was from the lumen or the cir~ulation.~~ shown that aspirin greatly increased the ionic permeability of the mucosa and broke down its normal barrier to diffusion of sodium, potassium and hydrogen ions, so that absorption of hydrogen ions through the damaged barrier from the stomach led to mucosal bleeding. During active secretion of acid these effects It has also been proposed that aspirin decreased the rate may be enhan~ed.~~t33 of formation of the mucous lining and also lowered its resistance to proteolysis.34 Acetazolamide damage to the mucosa appeared to depend upon the presence of acid and, in addition, it accelerated the l o s s of hydrogen ions from the luminal fluid through the surface muc0sa.~5 Enhancement of gastric secretion was suggested to be a part of the mode of action of caffeine in ul~erogenesis.3~ The polysaccharide carrageenin has been found to have a protective effect from ulceration induced by histamine, cortisone or the Shay t e ~ h n i q u e . ~ ~ , ~ ~ Absorption and Transport Most experimental studies on absorption and transport were carried out to determine mechanism of these actions rather than to search for agents affecting in vivo action. Much of the work was done in in vitro gut sac preparations. Stimulation of glucose and sodium transport by reserpine resulted, at least in part,3$s a result of release of catecholamines from storage sites in the intestine. Similarly, Lepinephrine and &norepinephrine stimulated glucose and sodium absorption, but stimulation was blocked by prior treatment with dichloroisoproterenol or ergotamine, although the latter two agents alone had no effect. Cyclic AMF’ also had no effect.40 It was concluded that calcium binding substances reduced gastrointestinal absorption of drugs mainly by markedly decreasing the rate of gastric emptying.41 Transport of amino acids across the intestinal wall was inhibited by 4deoxypyridoxine, a vitamin B6 antagonist, whereas glucose transport was unaffected. It was concluded that vitamin B6 may be necessary for a metabolic process involving the amino acid carrier systems.42 CLINICAL INVESTIGATIONS Peptic Ulcer Therapy Anticholinergics: Although anticholinergic drugs are prescribed for the inhibition of gastric acidity in peptic ulcer disease, there was no indication that average doses of these agents significantly inhibited gastric acid secre-

Chap. 10

Gastrointestinal

Bolhofer and Brodie

103 -

Thus, for any significant degree of inhibition of gastric secretion, an anticholinergic agent must be administered at the maximally tolerated However, combinations of antacids and anticholinergics were found to be more effective in reducing gastric acidity than either drug given alone. Several new anticholinergics have undergone clinical trial, but none appeared to be any more potent or selective in action than a t r ~ p i n e . ~ ~Glycopyrrolate ,~~ (1-methyl-3-pyrrolidyl aphenylcyclopentaneglycolate methobromide) (IX) has been

CH3

'CH3

Br-

shown to be a clinically useful anticholinergic,47'48 but the drug had no special qualities which distinguished it from the more than 50 anticholinergics now available. The Wphenylcyclohexaneglycolate congener of glycopyrrolate, which was equiactive in animals, was found to be only minimally effective in suppressing gastric acidity in man.49 Antacids: These agents are widely used to reduce gastric acidity and relieve pain in the peptic ulcer patient. The mechanism of pain relief was unclear, since new telemetry techniques for measuring gastric pH50 have confirmed the older reports that the acid-neutralizing action lasted only from 30 to 40 minutes, while pain relief lasted for hours. A new antacid, bismuth aluminate, has been reported to be effective in relief of pain, but this agent had no effect on gastric acidity or peptic a~tivity.~' The effect was postulated to be due to a coating action of the gastric mu~osa.~* As with anticholinergics, the antacids53 gave symptomatic relief, but did not alter the natural course of the disease. Antipeptic Agents: Since acid-pepsin digestion is considered to be essential for the production of peptic ulceration, regardless of the underlying cause of the disease, reduction of pepsin concentration of gastric juice remains a practical aim in ulcer therapy. Sun54 has reviewed this area with particular attention to a new antipeptic agent, Depepsen, a sulfated amylopectin. The place of these agents in peptic ulcer treatment is still controversial. Gastric Ulcer Therapy Gastric ulcer patients differ from those with duodenal ulcer, in that the former have normal or low gastric acidity and -amuch higher incidence of gastric cancer Carbenoxolone (B iogastrone) , the pentacyc 1ic triterpene, glycyrrhetinic acid, has been reported to give symptomatic relief in gastric ulcer patients and to increase the rate of gastric ulcer healing, confirming the original clinical s t ~ d i e s . 5 ~Some ~ ~ investigators, however, have failed to find effects better than placebo,58 and side effects related to salt and water retention were common. The mechanism of the antiulcer action was not clear, but could be related to the drug's antiinflannnatory effects.

.

104

Sect. I1 - P h a r m a c o d y n a m i c s

A r c h e r , Ed.

Functional Gastrointestcnal Disorders Anticholinergics have been used f o r treatment of hypermotility s t a t e s with some success, but with t h e usual s i d e e f f e c t s . A l a r g e series of thioxanthene d e r i v a t i v e s was studied f o r s e l e c t i v e anticholinergic action, and 9-flN-methyl3-piperidy1)methylJ thioxanthene, marketed as methixene (Trest) (X) , has been found t o provide symptomatic r e l i e f w i t h l o w incidence of atropine-like s i d e

H C-

.

3

e f f e c t s 59s60 It i s too e a r l y t o t e l l i f t h i s drug w i l l replace t r a d i t i o n a l anticholinergic treatment i n hypermotility states. I n t h e carcinoid syndrome, i t has been suggested t h a t serotonin was responsible f o r t h e d i a r r h e a seen i n t h i s condition. Treatment with a serotonin a n t a g o n i s t J 6 l methysergide, was e f f e c t i v e i n c o n t r o l l i n g t h e diarrhea and was f u r t h e r evidence f o r t h e r o l e of serotonin i n i n t e s t i n a l m o t i l i t y . The search f o r agents which a l t e r smooth muscle a c t i v i t y yielded several new compounds. Antispasmodic e f f e c t s were reported f o r ipyrrole, 62 acetophenone63 and piperidine derivatives,64 as w e l l as d e h y d r o m e t h y s t i c ~ s nand ~ ~ 2-(2'phenylace tylhydraz ino)-4,6-bisdiethylamino- 1,3 ,5- t r i a z ine (Ciba 28,882-Ba) . 66 The spasmo enic e f f e c t of dihydrocodeine w a s reversed by n i c o t i n i c acid esteri f i ~ a t i o n . Nicotinyldihydrocodeine ~~ was found t o i n h i b i t drug-induced spasm of t h e b i l e duct sphincter. Stimulation of smooth muscle a c t i v i t y w a s reported f o r t et r ahydr oaminoacr i d i n e c ompounds 68

.

Metoclopramide ~-(2-diethylaminoethyl)-2-methoxy-4-amino-5-chlorobenzamide d i h y d r c x h l o r i d g (XI) has been widely used i n Europe as a "digestive C O W C H ~ C H ~ - N(C 2139

I

c1QH3

2 HC1

modifier" t o r e l a x t h e pylorus and increase g a s t r i c m o t i l i t y and as an a i d t o t h e x-ray study@ of the g a s t r o i n t e s t i n a l t r a c t . I t s primary use has been as an antiemetic. A t t h e present t i m e , t h i s d k g i s not a v a i l a b l e i n t h e United States.

Chap. 10

Gastrointestinal

Bolhofer and Brodie

105 -

Ulcerative Colitis Therapy The choice between medical and surgical treatment of this disease remains a problem to the clinician. Reviews of the l i t e r a t ~ r e ~indicated ~ , ~ ~ that steroids were the most commonly used drugs; however, as with anticholinergic therapy for peptic ulcer, they alleviated the symptoms but did not cure the disease. Drug Effects on Gastrointestinal Motility Stimulation of gastrointestinal motility has been studied, usually with isolated tissues, with a wide variety of drugs. Serotonin has been suggested to be a naturally occurring material which stimulates motility, perhaps as a local hormone. However, its role remained unclear, since it has been shown to stimulate human tissues in ~ i t r o but ,~~ up to 90% depletion in the rat did not inhibit peri~talsis.~3 A study on the isolated rat colon indicated that the effect of serotonin was dose-related: small doses had a direct effect on muscle fibers, while higher doses acted by stimulating parasympathetic ganglia in the gut wall.74 Bile Drug-induced jaundice as a side effect of phenothiazine derivatives is well documented. The effect of these drugs and C17~alkyl-substitutedsteroids was studied by in vivo and in vitro t e s t ~ , ~and s it was concluded that these agents inhibited glucuronyl transferase. The steroids prevented excretion of conjugated bilirubin by blocking a stage after conjugation, but the mechanism of phenothiazine jaundice was still unclear. The steatorrhea observed in patients receiving cholestyramine (a basic ion exchange resin which binds bile acids) and a diet containing triglyceride fats of normal chain length was eliminated by replacing the long chain triglycerides with medium chain triglycerides (less than C12). Bile acid absorption by the cholestyramine was comparable for both diets. The medium chain triglycerides may be of value in clinical management of patients with malabsorption due to biliary 0bstruction.7~ Salivary Glands Physalaemin, a polypeptide was found to be the most active sialogogic agent tested in rats and dogs.7f Its action appeared to be a direct one on the salivary gland, since its effect was not blocked by sympathomimetic, parasympathomimetic or ganglionic blockers, but its effect was reduced by serotonin. Drug-Induced Gastrointestinal Lesions The incidence of pathological changes in the gastrointestinal tract due to therapeutic agents has increased as new drugs and formulations appeared on the market. Gastrointestinal ulceration due to steroids and antiinflammatory drugs is well known and continues to be a major side effect. Reduction of ulcerogenic activit was reported with ketophenylbutazone as compared to phenylbutazone itself,78 while the use of indomethacin capsules reduced the incidence of peptic ulcers seen with indomethacin The mechanism of steroid-

tablet^.^'

106

Sect. I1

-

Pharmacodynamics

A r c h e r , Ed.

induced g a s t r o i n t e s t i n a l l e s i o n s i s s t i l l not resolved. Hydrocortisone d i d not a f f e c t g a s t r i c s e c r e t i o n i n t h e r a t , leading t o t h e conclusion t h a t some mechanism o t h e r increased g a s t r i c a c i d i t y was t h e cause of c o r t i c o s e r o i d ulceration.86518' There d i d not s e e m t o be a s p e c i f i c s t e r o i d ulcer8' a s distinguished from u l c e r s due t o o t h e r causes. It has been suggested83 t h a t s t e r o i d s aggravated e x i s t i n g inflammation by loosening i n t e r c e l l u l a r cement and permitting p e n e t r a t i o n of t h e mucosa by t h e g a s t r i c j u i c e . S t e r o i d therapy i n cancer p a t i e n t s appeared t o induce more severe g a s t r i c complications than ,in p a t i e n t s with nonmalignant disease.84

A new i a t r o g e n i c .lesion, small bowel u l c e r a t i o n following a d m i n i s t r a t i o n of enteric-coated t a b l e t s of potassium c h l o r i d e and a t h i a z i d e d i u r e t i c , 8 g 39 described i n l a t e 196485 and r a p i d l y confirmed by numerous c a s e r e p o r t s . Experimental s t u d i e s i n d i c a t e d t h a t t h e l e s i o n was due t o t h e release of a high l o c a l c o n c e n t r a t i o n of potassium from t h e enteric-coa ed t a b l e t over a s h o r t segment of t h e i n t e s t i n e . 9 0 I n one c l i n i c a l report," a p a r t i a l l y digested t a b l e t was found i n a l e s i o n c r a t e r i n t h e i n t e s t i n e . The t h i a z i d e d i u r e t i c d i d n o t appear t o be connected with t h e l e s i o n p r o d u c t i ~ n . ~ ~ , ~ ~ REFERENCES

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.

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Gastrointestinal

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&I.

36. 37. 38. 39 40. 41. 42. 43.

.

44.

45. 46. 47. 48 49 50. 51. 52. 53. 54. 55. 56. 57. 58

.

.

59 60. 61. 62.

63. 64.

107 -

108

Sect. I1

- Pharmacodynamics

A r c h e r , Ed.

65. H.J. Meyer, Arch. Intern. Pharmacodyn., 154, 449 (1965). 66. P.P. Spinnler, Arch. Intern. Pharmacodyn., 156, 217 (1965). 67. R.A. Cahen, A. Boucherle and M. Sautai, Compt. Rend. SOC. Biol., 159, 1123 (1965). 68. M.J. Bleiberg, Life Sci., 4, 449 (1965). 69. R. Van Lerberghe, Acta Gastroent. Belg., 28, 440 (1965). 70. M. Sparberg and J.B. Kirsner, Current Therap. Res., 7, 324 (1965). 71. T.P. Almy and A.G. Plaut, Gastroenterology, 49, 295 (1965). 72. D.J. Fishlock, A.G. Parks and V. Dewell, Gut, 6, 338 (1965). 73. D.J. Boullin, Brit. J. Pharmacol., 23, 14 (1964). 74. K. Ulrich, J. Pharm. Pharmacol., 17, 710 (1965). 75. T. Hargreaves, Nature, 206, 154 (1965). 76. R.B. Zurier, S.A. Hashin and T.B. Van Itallie, Gastroenterology, 49, 490 (1965). 77. G. Bertaccini and C. de Caro, J. Physiol. (Lond.1, 181, 68 (1965). 78 2. Horakova, 3. Metys and V. Cepelak, Therapie, 20, 617 (1965). 79. 0. L%rgren and E. Allander, Brit. Med. J., 1, 996 (1965). 80. P.H. Guth and R. Mendick, Am. J. Gastroenterol., 44, 545 (1965). 81. R.E. Wiederanders, J, Lancet, 85, 315 (1965). 82. A.E. Garb, E.H. Soule, L.G. Bartholmew and J.C. Gain, Arch. Intern. Med., 116, 899 (1965). 83. D.H. Johnston, Gastroenterology, 48, 823 (1965). 84. D.L. Roseman and S.C. Economou, Arch. Surg., 90, 488 (1965). 85. D.R. Baker, W.H. Schrader and C.R. Hitchcock, J. Am. Med. ASSOC., 190, 586 (1964). 86. R.J. Rosen and D.T. Borucki, J. Am. Med. ASSOC., 191, 419 (1965). 87. D.J. Buchan, F. Murphy and C.S. Houston, Gastroenterolopy, 48, 808 (1965). Lancet, 2, 593 (1965). 88. L. 89. T.B. Binns, A.K. Pittman, D.M. Burley and J.M. O'Brien, Brit. Med. J., 1, 248 (1965). 90. S.J. Boley, L. Schultz, A. Krieger, S. Schwartz, A. Elguezabal and A.C. Allen, J. Am. Med. ASSOC., 192, 763 (1965). 91. H. Payan and A. Blaustein, Gastroenterology, 48, 877 (1965). 92. R.M. Diener, D.H. Shoffstall and A.E. Earl, Toxicol. Appl. Pharmacol., 7, 746 (1965). 93. F.D. Lawrason, E. Alpert, F.L. Mohr and F.G. McMahon, J. Am. Med. Assoc., 191, 641 (1965).

sf,

S e c t i o n I11 Editor:

Edwin H.

Chemotherapeutic Agents

Flynn, E l i L i l l y a n d Co.,

C h a p t e r 11. Edwin H.

-

Indianapolis,

Ind.

A n t i b i o t i c s and R e l a t e d Compounds

Flynn, E l i L i l l y and Co.,

Indianapolis,

Ind.

The y e a r 1965 w a s marked by a p p e a r a n c e of a number of v a l u a b l e r e p o r t s b e a r i n g on t h e u s e of a n t i b i o t i c s i n t h e chemotherapy of i n f e c t i o u s d i s e a s e s . Nek advances have been made i n u n d e r s t a n d i n g t h e b i o s y n t h e s i s of some a g e n t s and e x p e r i m e n t s have been r e p o r t e d which were d e s i g n e d t o make t h e mode of a c t i o n u n d e r s t a n d a b l e . Although n o t a l l - i n c l u s i v e , p a p e r s r e f e r r e d t o i n t h e f o l l o w i n g pages s h o u l d g i v e t h e r e a d e r a s t a r t i n g p o i n t f o r f u r t h e r r e a d i n g and may i n d i c a t e t h e d i r e c t i o n s b e i n g t a k e n by r e s e a r c h i n t h i s a r e a . Penicillins new d e r i v a t i v e s of 6 - a m i n o p e n i c i l l a n i c a c i d ( I) c o n t i n u e t o

f i n d a p l a c e b o t h i n e x p e r i m e n t a l work on i n f e c t i o u s d i s e a s e Two d e r i v a t i v e s c l o s e l y r e l a t e d t o and i n m e d i c a l p r a c t i c e . o x a c i l l i n ( 11) a r e c l o x a c i l l i n ( 111) and d i c l o x a c i l l i n ( IV) These compounds, though d e s c r i b e d e a r l i e r , have been s t u d i e d further. It has been said1 t h a t c l o x a c i l l i n i s p r i m a r i l y u s e f u l i n i n f e c t i o n s c a u s e d by p e n i c i l l i n a s e p r o d u c i n g s t a p h y l o c o c c i . Blood l e v e l s a f t e r o r a l and i n t r a m u s c u l a r a d m i n i s t r a t i o n w e r e s l i g h t l y more d e l a y e d when compared w i t h o x a c i l l i n b u t l a s t e d longer. Peak l e v e l s were t h o u g h t t o be s i m i l a r , a l t h o u g h o t h e r workers2 have r e p o r t e d b e t t e r a b s o r p t i o n t h a n t h a t o b t a i n e d w i t h oxacillin. A c l i n i c a l s t u d y 2 of c l o x a c i l l i n showed good r e s u l t s i n s t a p h y l o c o c c a l , pneumococcal and s t r e p t o c o c c a l i n f e c t i o n s and c o n s i s t e n t l y h i g h e r a n t i b a c t e r i a l blood l e v e l s

.

110

Sect. 111

-

Chemotherapeutics

F l y n n , Ed.

a f t e r o r a l administration. It w a s c o n c l u d e d t h a t c l o x a c i l l i n c o u l d s u b s t i t u t e f o r m e t h i c i l l i n when o r a l t h e r a p y i s f e a s i b l e . D i c l o x a c l l l i n a p p e a r s t o be a b s o r b e d e x t r e m e l y w e l l , g i v i n g p e a k blo& l e v e l 8 t w i c e t h u s e of c l o x a c l l l i n and f o u r - f o l d greater than o x a c i l l i n . g It w a s f e l t t h a t serum b i n d i n g w a s comparable t o t h e o t h e r i s o x a z o l y l p e n i c i l l i n s . These blood l e v e l s have been confirmed.4 A m p i c i l l i n ( V ) , known t o be a b s o r b e d w e l l o r a l l y and t o have a b r o a d e r s p e c t r u m of a c t i v i t y t h a n o t h e r p e n i c i l l i n s , has been s t u d i e d a s t h e sodium s a l t f o r p a r e n t e r a l a d m i n i s t r a t i o n . 5 R e s u l t s i n d i c a t e d t h i s form t o be s a t i s f a c t o r y f o r p a r e n t e r a l u s e , t h u s e n h a n c i n g t h e c l i n i c a l v a l u e of a m p i c i l l i n . H e t a c i l l i n ( V I ) , t h e r e a c t i o n p r o d u c t of a m p i c i l l i n and a c e t o n e , has been r e p o r t e d . 6 It is s a i d t o g i v e more p r o l o n g e d b l o o d l e v e l s a f t e r o r a l dosage t h a n does a m p i c i l l i n , and a p p a r e n t l y is a c t i v e i n v i v o by v i r t u e of h y d r o l y s i s t o ampicill~n.~

N a f c i l l i n ( V I I ) has been r e p o r t e d t o be a n e f f e c t i v e and w e l l t o l e r a t e d a n t i s t a p h y l o c o c c a l a g e n t comparable t o o t h e r penicillinase resistant penicillins.* a - a l k y l d e r i v a t i v e s of phenoxymethyl p e n i c i l l i n ( p e n i c i l l i n V) have been d e s c r i b e d and t u r n o u t t o be e s s e n t i a l l y i n a c t i v e as a n t i b a c t e r i a l s u b s t a n c e s when compared w i t h t h e u n s u b s t i t u t e d compound.8 A c t i v e d e r i v a t i v e s of 6 - a m i n o t h i o p e n i c i l l a n i c a c i d ( V I I I ) have been r e p o r t e d . 1 0 An i n t e r e s t i n g s e r i e s i s t h a t r e p r e s e n t e d by I X ; t h i s member showing good gram n e g a t i v e as w e l l as gram p o s i t i v e a c t i v i t y . ' l

(VIII)

A p r o p o s a l c o n c e r n i n g t h e mechanism of a c t i o n of p e n i c i l l i n s on t h e b a c t e r i a l c e l l has been advanced.12 An i n t e r e s t i n g p a p e r c o n c e r n i n g t h e i n i t i a l s t r u c t u r a l l e s i o n s roduced by p e n i c i l l i n a c t i n g on t h e b a c t e r t a l c e l l has appeared. It v e r i f i e s a h i g h l y s p e c i f i c p o i n t o f a t t a c k by t h i s a n t i b i o t i c .

Antibiotics

Chap. 11

Flynn

111 -

A w o r t h w h i l e r e v i e w of p e n i c i l l i n s h a s a p p e a r e d L 4 and a book h a s been p u b l i s h e d x S which is c o n c e r n e d p r i m a r i l y w i t h b i o c h e m i c a l and b i o l o g i c a l f a c t o r s r e l a t e d t o p e n i c i l l i n . Cephalosporins The c e p h a l o s p o r i n g r o u p of a n t i b i o t i c s , whose g e n e s i s may be t r a c e d t o t h e d i s c o v e r y of c e p h a l o s p o r i n C ( X ) , h a s demons t r a t e d t h e i r v a l u e i n t h e t r e a t m e n t of i n f e c t i o u s d i s e a s e . C e p h a l o t h i n ( X I ) , t h e f i r s t of t h e s e s u b s t a n c e s t o find wides p r e a d u s e , w a s f o l l o w e d by c e p h a l o r i d i n e ( X I I ) which is now employed in many c o u n t r i e s f o r t h e r a p y of b a c t e r i a l i n f e c t i o n s . It seems a p p a r e n t t h a t o t h e r v a l u a b l e compounds of t h i s c l a s s may be e x p e c t e d .

X, R = H 0 2 C - C H N H 2 ( C H 2 ) 3 C O XI,

R = O H z C O - , S

XIII,

-

R'

, R'

= CHsC02-;

= CH3C02-;

R = D - C B H ~ C H N H ~ C O - , R'

CH3C02-

C e p h a l o r i d i n e h a s been e v a l u a t e d i n a number of c l i n i c a l and l a b o r a t o r y o t h e r r e p o r t s n o t c i t e d h e r e may be f o u n d in t h e A b s t r a c t s of t h e F i f t h I n t e r s c i e n c e C o n g r e s s on A n t i m i c r o b i a l Agents and Chemotherapy. It c a n be s a i d i n g e n e r a l t h a t t h e a g e n t w a s e f f e c t i v e i n a v a r i e t y of b o t h gram n e g a t i v e and gram p o s i t i v e b a c t e r i a l i n f e c t i o n s . Cephaloridine was ' i n e f f e c t i v e a g a i n s t Pseudomonas, t h e t u b e r c l e b a c i l l u s , a n d fungi. I n a comparison w i t h c e p h a l o t h i n s i g n i f i c a n t d i f f e r e n c e s in t h e r a p e u t i c r e s p o n s e were n o t d e t e c t e d . 1 7 G e n e r a l l y s a t i s f a c t o r y r e s u l t s were s e e n i n a p e d i a t r i c study" of cephaloridine. A s e r i e s of 92 c a s e s w i t h a v a r i e t y of i n f e c t i o n s w a s s t u d i e d with impressive r e s u l t s . l s !Cwo c a s e s of r e n a l f a i l u r e were e n c o u n t e r e d w h i l e u n d e r t r e a t m e n t w i t h 8-12 grams of c e p h a l o r i d i n e d a i l y ; t h e complex h o s p i t a l c o u r s e s d i d n o t I n a n o t h e r s e r i e s of 70 a l l o w d i r e c t i m p l i c a t i o n of t h e d r u g . c a s e s a t what would seem t o be low d a i l y d o s e s , good r e s u l t s were r e p o r t e d . 2 0 The same r e p o r t m e n t i o n s t o x i c c h a n g e s in r a b b i t k i d n e y a t a s i n R l e d o s e of 90 mg./kg. b u t not a t 45 mg./kg. d a i l y f o r e i g h t weeks. A l l of t h e f o r e g o i n g s t u d i e s employed p a r e n t e r a l a d m i n i s t r a t i o n . The b a c t e r i c i d a l a c t i v i t y o f c e p h a l o r i d i n e h a s been commented upon f a v o r a b l y 2 1 a n d i t s s t a b i l i t y t o s t a p h y l o c o c c a l p e n i c i l l i n a s e h a s been ~ t u d i e d . ~ ~ AJ l ~ l e 3r g y t o c e p h a l o r i d i n e h a s r e c e i v e d n o t i c e 2 * as h a s a c a s e of a n a p h y l a x i s a t t r i b u t e d t o c e p h a l o t h i n . 2g

112

S e c t I11

- Chemotherapeutics

F l y n n , Ed.

A n i n t e r e s t i n g i n v e s t i g a t i o n of s y n e r g i s m between p e n i c i l l i n s and c e p h a l o s p o r i n s a g a i n s t pS. pyocyanea h a s been p u b l i s h e d show‘ing marked enhancement of a c t i v i t y i n c e r t a i n c a s e s . 26 C e p h a l o g l y c i n ( X I I I ) has been e v a l u a t e d 2 7 I n t h e l a b o r a t o r y b o t h in v i t r o and in v i v o and shows a good l e v e l of a c t i v i t y v e r s u s gram n e g a t i v e organisms. The a r t i c l e p o i n t s o u t some d i f f i c u l t i e s i n h e r e n t in e v a l u a t i n g a s u b s t a n c e which is r e l a t i v e l y u n s t a b l e in s o l u t i o n as is t h e c a s e w i t h c e p h a l o g l y c in. Chemical p a p e r s have a p p e a r e d , one d e s c r i b i n g p h y s i c a l c h e m i c a l d a t a on a s e r i e s of c e p h a l o s p o r i n s P 8 and a n o t h e r m e n t i o n i n g p r e p a r a t i o n of a number of d e r i v a t i v e s . = e Lincomyc in L l n c o m n i n . a n a n t i b i o t i c e f f e c t i v e in t r e a t m e n t of i n f e c t i o n s caus;d by gram p o s i t i v e organisms, is f i n d i n g Earlier w i d e s p r e a d u s e in t h e . t r e a t m e n t of human d i s e a s e . r e p o r t s ( 1 9 6 3 and l a t e r ) d e m o n s t r a t i n g c l i n i c a l e f f i c a c y have been e x t e n d e d . 30-91 T h a t s t r u c t u r a l m o d i f i c a t i o n of l i n c o m y c i n is p o s s i b l e w i t h o u t loss of a n b i b a e t e r i a l a c t i v i t y has been shown in s e v e r a l papers.32’3s*34 Some s t u d i e s o n b i o s y n t h e s i s have been r e p o r t e d . 3 5

\

w r a l r e p o r t s c o n c e r n e d w i t h a new e n t i t y c a l l e d kasugamycin hav; a p p e a r e d . T h i s s u b s t a n c e has been shown t o have t h e s t r u c t u r e , XIV.36 O r i g i n a l l y d i s c o v e r e d b e c a u s e of i t s

H2N-i-iPHs NH

H

~~

( XIV)

H

OH

o

~

o

~

OH

a c t i v i t y i n p. o r y z a e i n f e c t i o n s of t h e r i c e p l a n t , it has a n t i b a c t e r i a l a c t i v i t y of a f a i r l y wide r a n g e , though of a low order.37 O r a l l y a b s o r b e d , and a p p a r e n t l y r e l a t i v e l y n o n - t o x i c , kasugamycin may f i n d a p p l i c a t i o n in t r e a t m e n t of human infections. I t s u t i l i t y in Pseudomonas i n f e c t i o n s of t h e g e n i t o u r i n a r y t r a c t has been s u g g e s t e d in one pa er.36 D e r i v a t i v e s of r i f a m y c i n have been r e p o r t e d e * 4 0 a n d a t l e a s t one compound has been shown t o be e f f e c t i v e in human disease.41 The d i e t h y l a m i d e of r i f a m y c i n B has shown e f f e c t i v e n e s s i n a c u t e c h o l e c y s t i t i s and i n s t a p h y l o c o c c a l i n f e c t i o n s . L e s s favorab1.o r e s u l t s were o b t a i n e d in pneumonia. A revidw has a p p e a r e d on r i f a m y c i n SV.42

P

Chap. 1 1

Antibiotics

Flynn

113 -

A d d i t i o n a l i n f o r m a t i o n on t h e g e n t a m i c i n complex, f i r s t r e p o r t e d i n 1963, h a s been made a v a i l a b l e d u r i n g 1965. T h i s m u l t i p l e f a c t o r a g e n t ( s ) has been shown t o have v a l u e i n t h e t r e a t m e n t of Pseudomonas s e p s i s i n burns4cg and t h e ( r a b b i t ) eye44 and h a s been u s e d i n p e d i a t r i c s t o t r e a t gram n e g a t i v e i n f e c t i o n s . 4 5 Although somewhat t o x i c , g e n t a m i c i n a p p e a r s t o have c l i n i c a l v a l u e . Some c h e m i c a l s t u d i e s have been r e p o r t e d , 4 6 showing t h e p r e s e n c e i n t h e m o l e c u l e of D-glucosamine, 2 - d e o x y s t r e p t a m i n e and a n amino s u g a r named g e n t o s a m i n e A. A c o n f e r e n c e t o d i s c u s s new a n t i t u b e r c u l o u s a g e n t s w a s h e l d by t h e New York Academy of S c i e n c e s September 13-15, 1965, i n N e w York C i t y . The u s e of e t h a m b u t o l and capreomycin i n t h e r a p y was discussed. Aatinospectacin, a n a g e n t w i t h broad spectrum a ~ t i v i t y , 4 ~ showed promise i n a c u t e i n f e c t i o n s of t h e g e n i t o u r i n a r y t r a c t s 4 ' The r e l a t i v e l y low p e r c e n t a g e of "good" r e s p o n s e s w a s p r o b a b l y due t o i n a d e q u a t e dosage. I s o l a t i o n a n d b i o l o g i c a l a s s e s s m e n t of coumermycin has been reported.4a The s t r u c t u r e has been e s t a b l i s h e d 5 O and i t s s y n t h e s i s from a n o v o b i o c i n i n t e r m e d i a t e h a s been mentioned.'l Chemically r e l a t e d t o n o v o b i o c i n , coumermycin A 1 shows c r o s s r e s i s t a n c e w i t h novobiocin; i t a p p e a r s t o be more a c t i v e i n It is i d e n t i c a l t o sugordomycin. Coumermycin A 2 i s general. c l o s e l y r e l a t e d t o A 1 hhemically.s2 Chemistry of t h e polymyxins h a s been discassed.'" S y n t h e s i s of polymyxin E ( c o l i s t i n A) w a s t h e s u b j e c t of a r e c e n t study.s4 S t r u c t u r e s t u d i e s were d e s c r i b e d showing t h e i d e n t i t i e s of polymyxin El and E2 w i t h c o l i s t i n A and B, respectively.' F u s i d i c a c i d , t h e s t e r o i d a l a n t i b i o t i c now i n c l i n i c a l u s e , has been shown t o be i d e n t i c a l w i t h ramycin.56 A comprehensive s t u d y of t h e e f f e c t of s t r u c t u r a l v a r i a t i o n on a n t i b a c t e r i a l The s t r u c t u r a l r e l a t i o n s h i p w i t h a c t i v i t y has been r e p o r t e d . s 7 h e l v o l i c a c i d and c e p h a l o s p o r i n P1 i s mentioned. Erythromycin has been shown t o be e f f e c t i v e c l i n i c a l l y 5 * in pneumonia due t o Mycoplasma pneumoniae, t h e Eaton a g e n t pneumonia. Bios n t h e s i s and metabolism of e r t h r o m y c i n s were s t u d i e d u s i n g 1-f4c p r o p i o n a t e as p r e c u r s o r . sg The a g l y c o n e w a s formed and gave e r y t h r o m y c i n s A, B, and C. A biosynthetic scheme w a s proposed. The s t r u c t u r e s of s p i r a m y c i n and magnamycin were published.6o The s t r u c t u r e of magnamycin r e p r e s e n t s a r e v i s i o n of an e a r l i e r p r o p o s a l . The s t r u c t u r e of viomycin h a s been d e t e r m i n e d . e l Moenomycin, a macromolecule h a v i n g h i g h i n t r i n s i c a n t i b a c t e r i a l a c t i v i t y % v i t r o and i n v i v o when a d m i n i s t e r e d The recommendation p a r e n t e r a l l y , has been r e p o r t e d . 6 2 , 6 3 , 6 4 w a s made t h a t t h i s i n t e r e s t i n g s u b s t a n c e be r e s e r v e d f o r u s e a s a n a n i m a l growth s t i m u l a n t .

114

Sect. III

-

Chemotherapeutics

F l y n n , Ed.

T e t r a c y c l i n e d e r i v a t i v e s have been p r e p a r e d by a l k o x y a l k y l a t i o n of t h e amide f u n c t i o n . 6 5 The mode(s) of a c t i o n of t e t r a c y c l i n e s have been s t u d i e d u s i n g A. a e r o g e n e s . 0 0 They a r e s a i d t o i n t e r f e r e w i t h hydrogen t r a n s f e r r e a c t i o n s . A disturbing r e p o r t of t r a n s d u c t i o n of 2. a u r e u s t o t e t r a c y c l i n e r e s i s t a n c e in v i v o h a s a p p e a r e d . 6 7 Although a similar c i r c u m s t a n c e seems A further remote in humans, t h e p o s s i b i l i t y w a s noted. e l a b o r a t i o n of b i o s y n t h e t i c pathways f o r t e t r a c y c l i n e s h a s been provided.ee The i s o l a t i o n and c h a r a c t e r i z a t i o n of h-hydroxy-6m e t h y l p r e t e t r a m i d , a t e t r a c y c l i n e p r e c u r s o r accumulated by a b l o c k e d mutant, has been r e c o r d e d . e a A new t o t a l s y n t h e s i s of 6-deoxy-6-demethyltetracycline w a s a c h i e v e d by an e l e g a n t p r o c e d u r e .70 The c h e m i s t r y of t h e d e p s i p e p t i d e t y p e a n t i b i o t i c s ( s t r u c t u r e s made up of hydroxy- and amino a c i d m o i e t i e s l i n k e d t h r o u g h e s t e r a n d amide bonds) apd t h e i r mechanism of a c t i o n has been reviewed.71 A d e t a i l e d a c c o u n t of t h e c h e m i s t r y a l s o h a s been p u b l i s h e d . 7 2 It is t h o u g h t t h a t t h e s e s u b s t a n c e s a c t by a l t e r i n g ion t r a n s p o r t t h r o u g h c e l l membranes v i a changes in t h e l i p o p r o t e i n component of t h e c e l l membrane. Some s t r u c t u r a l a s p e c t s of t h e vancomycin m o l e c u l e have been d e f i n e d . 7 3 C l i n i c a l l y , vancomycin has been shown t o be e f f e c t i v e in s t a p h y l o c o c c a l e n t e r o c o l i t i s . 7 4 , 7 5 L y s o s t a p h i n , a l y t i c enzyme p r e p a r a t i o n s p e c i f i c f o r t h e genus S t a p h y l o c o c c u s , h a s been r e p o r t e d t o be a m i x t u r e of two enzymes, a h e x o s a m i n i d a s e and a p e p t i d a s e . 7 6 L y t i c a c t i o n is due t o t h e p e p t i d a s e . I t s t h e r a p e u t i c a c t i v i t y i n animals has been d i s c u s s e d . 7 7 A paper h a s been p u b l i s h e d which r e c o g n i z e s t h e d i f f i c u l t y of d e t e r m i n i n g r e l a t i v e c l i n i c a l e f f i c a c y of a n t i b i o t i c s and proposes p o s s i b l e alternatives.78 The i m p o r t a n c e of o b t a i n i n g a n optimum b a l a n c e of p r o p e r t i e s i n a d d i t i o n t o u s a b l e a n t i b a c t e r i a l a c t i v i t y has been n e g l e c t e d by many e x p e r t s . A comprehensive s t u d y and d i s c u s s i o n of serum b i n d i n g of a n t i b i o t i c s has been p u b l i s h e d . 7 e S t i l l t o be c o r r e l a t e d e x p e r i m e n t a l l y is t h e s u g g e s t e d d e l e t e r i o u s e f f e c t on c l i n i c a l e f f e c t i v e n e s s v i t h t h e n a t u r e and d e g r e e of serum p r o t e i n binding P o s s i b l e involvement of p r o t o p l a s t forms of b a c t e r i a in an i n f e c t i o n have been c o n s i d e r e d . I n a n e x p e r i m e n t a l approach, e v i d e n c e w a s o b t a i n e d t o s u g g e s t t h a t a c o m b i n a t i o n of p e n i c i l l i n a n d kanamycin e l i m i n a t e d b o t h c l a s s i c a n d p r o t o p l a s t forms in e x p e r i m e n t a l p y e l o n e p h r i t i s . 8 0 Major advances in i n f e c t i o u s d i s e a s e t h e r a p y a r e d e s t i n e d t o o r i g i n a t e from s t u d i e s of t h e r e l a t i o n s h i p of a b e r r a n t b a c t e r i a l forms t o disease. The b i o s y n t h e s i s of m a c r o l i d e a n t i b i o t i c s w a s considered.81 A s p e c t s of t h e b i o g e n e s i s of s e v e r a l o t h e r a n t i b i o t i c groups have been c o v e r e d in a c o l l e c t i o n of papers.82 A u s e f u l r e v i e w of t h e c h e m i s t r y of nev a n t i b i o t i c s h a s appeared.89

--

.

Chap. 11

115 -

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Antibiotics

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H. Kawaguchi, T. Naito and H. Tsukiura, g., 18, ll (1965). A. Furlenmeier, J. Berger, A. Batcho, €I Spiegelberg, . H. Schocher, 0. Keller, B. Pecherer and B. Vaterlaus, Chimia, 597 (1965). H. Kawaguchi, T. Miyaki and H. Tsukiura, J. Antibiotics (Tokyo),

a

Ser. A, &l 220 (1965). K. Vogler, h e w . Chem., 77, 974 (1965). R. 0. Studer, Helv. Chim.Tcta, 48, 1371 (1965). T. Suzuki, K. Hayashi, K. FujikaG and K. Tsukamoto, J. Biochem. (Tolgro), 57, 226 (1965). H. VanderGghe, P. VanDijck and P. DeScmer, Nature, 225, 710 (1965). W. 0. Godtfredsen, W. VonDaebne, L. Tybring and S. Vangedsl, J. Med. B., 8, 15 (1966). J. R. Rasch and W. J. Mogabgab, "Fifth Interscience Conference on Antimicrobial Agents and Chemotherapy" Abstracts, American Society for Microbiology, Ann Arbor, Mich. , 1965, p. 36.

Antibiotics

Chap. 1 1

Flynn

59. P. Hung, C. L. Marks and P. Tardrew, J. Biol. Chem., 60. M. Kuehne and B. Benson, J. Am. Chem. S O C . , ~ , 4660 61. J. Dyer, C. Kellogg, R. Nassar and W. Streetman, Tetrahedron Letters, 1965, 585. 62. m e s e m a n n , P. Prave, A. Steigler and K. H. WaUhauser, "Fifth

63. 64. 65. 66.

Interacience Conference on Antimicrobial Agents and Chemotherapy" Abstracts, American Society for Microbiology, Ann Arbor, Mich., 1965, p. 44. E. V. Wasielewski, R. Muschaweck and E. Schutze, E., p. 45. F. Bauer and G. Dost, E.,p. 46. C. R. Temorria and R. C. Esse, J. Med. Chem.,& 870 (1965). J. Benbough and G. A. Morrison, J. Pham. Phannscol., 17 409 (1965). H. Jarolmen, A. Bondi and R. L. Crowell, J. Bacteriol.T&, 1286 (1965). P. A. Miller, J. A. Hash, M. Lincks and N. Bohonos, Biochem. Biophys. Res. Cam., 325 (1965). J. R. D. McCormick and E. R. Jensen, J. Am. Chem. SOC., ,7'8 1794 (1965). H. lvfuxfeldt and W. Rogalshi, 87, 933 (1965). M. M. Shemyakin, "Fifth Interscience2onference on Antimicrobial Agents and Chemotherapy" Abstracts, American Society for Microbiology, Ann Arbor, Mich., 1965, p. 16. M. M. Shemyakin, E. I. Vinogradova, M. Yu. Feigina, N. A. Aldanova, N. F. Loginova, I. Ryabova and I. Pavlenko Experientia, 21, 548 (1965). F, J. Marshall, J. Med. Chem.,A ' , 18 (19651. J. F. Wallace, R. H. Smith and R. G. Petersdorf, New Engl. J. Med., 2 3 , 1014 (1965)W. E. Herrell, Clin. Med., 72, 19U (1965). H. P. Browder, W. A. Zy-7 J. R. Young and P. A. Tavormina, Biochem. &383 (1965). Biophys. Res. Canrm., I E. F. Harrison and C. B. Cropp, "Fifth Interscience Conference on Antimicrobial Agents and Chemotherapy" Abstracts, American Society for Microbiology, Ann Arbor, Mich., 1965, p. 115. B. A. Waisbren, Am. J. Med. Sci., 2 0, 406 (1965). G. N. Rolinson and R. Sutherland, J. E'harmacol., 3, 638 (1965). J. Z. Montgamerie, G. M. Kalmanson, W. L, Hewitt and L. B. Guze, "Fifth Interscience Conference on Antimicrobial Agents and Chemotherapy" Abstracts, American Society for Microbiology, Ann Arbor, Mich., 1965,

E.,

72.

73 74. 75 76

77. 78 79

80.

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At.

P. 78. 81. H. Brisebach, p. 22. 82. Z. Vanek and Z. Hostalek, Eds., "Biogenesis of Antibiotic Substances," Academic Press, New York, N. Y., 1965. 83 E. P. Abraham, Am. J. Med., 39, 692 (1965).

s.,

K.

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Sect. I11

-

Chemotherapeutics

Flynn, Ed.

Chapter 12. Synthetic Antibacterial Agents Robert G. Shepherd, Lederle Laboratories, American cyanamid Co., Pearl River, New York Developments during 1965 involved primarily laboratory and clinical study of analogs of known antibacterial structures and of their metabolism and mechanism of action. The importance of antibacterials is indicated by the large research effort being expended. The difficulty of finding new antibacterial structures is demonstrated by the fact that Only a very few have been reported in this decade in spite of this effort. Most of the 119 y e a r s since the beginning (Semlweiss 1847 and Lister 1865) of modern(1) antibacterial chemotherapy have been spent in stagnation or in significant but slow improvement on the small numbers of different active types so far discovered. Into the attack on the antibacterial frontiers are being brought biochemistry at the enzyme level, molecular vibrations, electronic energy-level calculations and pharmacokinetics via computers but the push-button age of "magic bullets" is still far in the future. In Vivo Actives.--The new compounds first shown by published data in 1965 to be active against infections in animals are discussed here. A laboratory study(2) on 2-sulfanilamido-4,6-diethyl-s-triazine showed it to be the most active of the sulfatriazines in vlvo an3 the first clinical report was promising(3). It is highly soluble, well absorbed, less conjugated than other clinical sulfas, and excreted largely unchanged(3). Its behavior is between short-acting and long-acting and its renal clearance is uniquely acceleratable by adjustment of urinary pH(3). Chemotherapeutic application of 4-sulfa-1,2,3-thiadiazoles is limited by their explosive intermediates (4). 5-Dimethylsulfamyl-antnthranilic hydrazide is only formally a sulfanilamide derivative since it is not antagonized by PAB. The in vivo antibactes ial activity(5) is rather specific structurally and is limited to Staphylococcus @D50 25-5Orng/kg) and Pneumococcus (ED50 250mg/kg) but, curiously, shows up in vitro only against Pneumococcus. Low activity against the expen imental TF3 infection in mice was reported for 2-carbethoxyaminoethylnbutylsulfide(6) and for beta-alanylhydroxamic acid(7). The latter shows some similarities in mechanism of action to cycloserine. Additional data(8) on 1-(aralkoxy and higher alkyloxy)-k, 6-diamino-l,2-dihydro-2,2-dimethyls-triazines show that some are active in vivo against Strep. hemolyticus but only at just below toxic doses. The broad-spectrum in vitro activity and the toxicity appear to be antifolic in nature. New activity (leprosy, below) was reported for ethambutol and for thalidomide as well as for some azo dyes. Antituberculous Agents.-Although major advances in TI3 therapy have been made, treatment is still far from satisfactory and the incidence of new urban cases is increasing, i n some instances drastically(9). Ethambutol (dextro-2,2'-ethylenediimino-di-l-butanol), one of two new active types reported in this decade, has successf'ully undergone clinical trials (10, 11, 12, 13) in several countries. Ethambutol acts clinically (12, 13) and experimentally(l4, 15) against strains of mycobacteria resistant to other agents, and combinations of sub-effective concentrations are inhibitory (16) in vitro. Resistant strains, which develop with difficulty(17, IS), have different biochemical characteristics than isoniazid-resistant strains (19). Human and bovine mycobacterial strains, which were experimentally

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made resistant to ethambutol, have been fo~na(16) to be attenuated for mice. Using 3513 and 32P to estimate protein and nucleic acid synthesis, it has been concluded(l9, 20) that ethambutol acts by interfering with a function of cellular polyamines and divalent cations in the synthesis or stabilization of RNA. Preliminary reports of its activity against human(21) and mine(22) leprosy have appeared. Quickly following a report drawing attention to the carcinogenic activity of isoniazid was a word of caution(23), much needed in the present, solnewhat hysterical atmosphere'surraundingW s . The production of tumors only in mice may well have prevented introduction of isoniazid in recent years but should not diminish its use until a harmful effect is established and weighed against its proven merits. Extensive investigation of N,N'-diaryl and N-aryl-N'Aeteroaryl thioureas appears to be ending in naught. N,N'-Bis(k-isoamyloxyphenyl)thiourea, the member most studied clinically, is judged to be only slightly active in man, by the usual criteria(24, 25, 26), on the basis of all the published controlled trials(27) in several countries. In addition, there is a high frequency(28) of natural resistance to this agent and cross-resistance with 4acetamidobenzalthiosemicarbazone(29). 2-Ethyl isonicotinic thicamide kthionamide) is undergoing clinical study at decreasing dosage. Although effective(30, 31) in producing clinical improvement and preventing emergence of resistance, high incidence of liver (31, 32, 33) and gastrointestinal(30, 34, 35) toxicity seems likely to restrict its use to retreatment of resistant cases. Mental disturbance and neural effects were cited(31, 36) as reasons for not using it in ambulatory patients. It is converted in man to several metabolites(37), among them the thioamide sulfoxide. It is not cross-resistant with isoniazid but shows B?m cross-resistance with thiocarbamylhydrazides (thiacetazone) and diarylthioureas(38, 39, 40, 41). Reports on the N-morpholino-methylde of pyrazinoic acid, proposed as a form of pyrazinamide with decreased toxicity and maintained activity(froln conversion to pyrazinamide), fail to confirm either of these characteristics(&). Gram-negative Antibacterials. -l-Ethyl-7-methyl-~oxo-l, 8-naphthyridine3-carbo~ylicacid(na1idixic acid) is one of two new active types reported & this decade. Its Gram-negative activity was first published by Lesher in 1962 and a brief structure-activity summary followed in 1964(43). There is no cross-resistance(44, 45) with other agents used in Gram-negative infections and its ED50 is comparable(4.6). The primary antibacterial action of nalidixic acid against E. coli is specific inhibition of DNA synthesis(47, 48). This antibacterial is unusual in being active as such and in rapidly forming an equally active metabolite, the 7-hydroxymethyl anslog(49). About one-third is excreted as this metabolite plus two-thirds as glucuronides of parent and metabolite. Antibacterial activity(50) in urine is predominantly (7:l) due to 7-hydroxymethyl metabolite while in tissue the two agents are about equal in concentration(@). Clinical assessments(51, 52) rate it rapidly effective orally against certain Gram-negative bacteria. Since genitourinary tract infections due to these organisms should be treated for several weeks to avoid relapse, it is an important shortcoming that a high 53) or after a degree of resistance can develop rapidly during therapy(% s m a l l number of transfers in vitro. A small trial(54) against brucellosis was successful. As is common in the early stages of clinical use, reports are conflicting on the breadth of application(55, 56, 57, 58) to urinary

120

Sect. 111 - Ghemotherapeutics

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infections (reported percentages of sensitive strains: 2-22s) Wb 8% 9%) and on side-reactions( 51, 59). Sulfanilamides.-Work on sulfa drugs is beginning its 4th decade with i& terest in and use of these agents continuing, especially since microbes ap~n apPliparently have not meanwhile progressively developed resistance(@). cation for sulfas (and other antibacterials) now receiving attention(6l) is treatmt of bacteriuria(frequently asymptamatic) of P r e V t W-n, a Condition with serious consequences for the child (higher incidence of' prematurity, neonatal death, congenital abnormalities, cerebral palsy, and lower I&) as well as for later chronic disease of the mother. The various drug-ofchoice uses of sulfas have been sunmarized(62) and chemotherapeutic research with sulfanilamide derivatives reviewed(63). B means of pharmacokinetic equations and computers, various papers(64, 657 attempt to adjust experimental and clinical dosage of sulfas to get equitherapeutic plasma-water concentration-time curves. Several long-acting sulfas introduced in recent y e a r s are in clinical evaluation (in approximate order of increasing persistence): 4-sulfa-3,6dimethoxypyrid~zine(66), 3-sulfa-4-iodo-5-methylisoxazole(67), 2-sulfa-5methoxypyrimidine(68), 2-sulfa-3-methoxypyrazine( 69), and ksdfa-5,6-dimethoxypyrimidine(70). The latter is so slowly excreted that oral, parenteral or rectal doses once per week or per disease episode are being explored(71, 72, 73). In contrast to its 2,&dimethoxy is-r, It yields only about 2$ of glucuronide. In relation to crystalluria potential(68), the l o w solubility of the long-acting sulfa8 is partly compensated for by glucuronide formation, but more significant is the amount of sulfa and/or metabolite excreted per unit time in relation both to actual urine flow rate and to the therapeutic dosage required for the particular sulfanilamide. Considerable study has been made of the binding of sulfas to blood albumin. Although bacterial inhibition varies directly with the percent unbound in a simple experimental mode1(74), the activlty relationship in vivo can not be aseumed to be the same as that of relative binding, and a highly bound compound need not be less desirable than a slightly bound one. Two agents with different degrees o f binding to blood albumin also differ in binding to tissue, in vltro potency, &, lipid solubility, excretion, metabolism, and distribution in body water, all of which directly or indirectly affect in vivo efficacy. In addition, the relationship of blood albumin binding to the degree of binding to the key enzyme site where the sulfa competes with PAB(75) is unknown. In an excellent sympoeium on interaction between drugs, Brodie(76) pointed out that binding is an advantageous and necessary characteristic without which a therapeutic agent would oscillate between toxic and inactive plasma concentrations and require frequent administration. Releasing an agent from binding to protein can be accomplished by means of a broadly similar chemical compound because of the rela tively non-specific nature of the binding but this release can lead to greater toxicity(76) and excretion and metabolism as w e l l as to the desired physiological action. Of interest in laboratory and clinical studies, it has been observed that the mouse, dog, man and other species v a r y 17-fold in extent of albumin binding of sulfas. Variation of binding is 2-fold among normal human sera, and 10-fold in certain illnesses(77) partly due to circulating blood constituents and partly due to albumin variation. The locus of binding of several sulfas to serum albumin has been shown(78) by relaxation-time

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measurements on high-resolution pmr spectra to involve the benzene ring and not the heterocycle; in 5-sulfa-1-phenylpyrazole the two benzene rings bind at different sites. Infonoation about sulfa drug metabolism in man has been reviewed(79). &Acetylation has been known to occur enzymatically to an extent dependent on N1-substituent and animal species. -Glucuronides(l-4$) result from nonenzymatic chemical reaction whileI*!J sulfamstestl (about I$) are true metabolites. Formation of N1-glucuronides occurs quite generally; with some N1heterocycles it amounts to only a few percent of dosage(sulfisoxazole, sulfathiazole) but with sulfamethoxyppidazine is substantial(l5-20$) and with sulfadimethoxine is 60-85$ of the substances excreted. 4-Sulfa-6-methoxy-2methylpyrimidine yields a large amount of 2-hydroxymethyl 0-glucuronide. Wfferences in the So;! infrared frequency in amino and imino isomers led to assignment of the sulfadimethoxine metabolite as NL rather than ring-N substltuted(80, 81). 5-Sulfa-1-phenylpyrazole is 70-9srenally excreted as a glucuronide of still uncertain structure( 82 ). 2-Sulf'a-4,5-dimethyloxazole is reported(83) in a study by thin-layer chromatography to be grossly unstable in water as w e l l as urine and blood, but a paper chrumatographic study (84)flatly contradicts this. Nitrof'urans.-Twenty-two years after the first report of their antibacterial activity, this class is receiving renewed clinical and laboratory interest. In spite of several thousand publications cove ng some six hundred analogs and 803116) structure-activity generalizations required: 5-N% o 3- or 4-substituan ring, some kind of 2-substituent and the critical characteristics that govern their activity especial. ly in vivo are far from clearly defined, The chemotherapeutic properties of the earlier nitrofurans have been reviewed(86). 4-(5'-Nitro-2'-furyl)-2-(3' '-pyridy1)thiazole is unusual in being a nitrofurylheterocycle bearing a heterocyclic substituent and in having broadspectrum activity in vivo (about 8 times as active as furaltadone and furadantin). Unfortunately, blood dyscrasias occur at doses just below the therapeutic range(87). An experimental model was reported(88) for the polyneuropathy which occurs with furadantin and other nitrofurans(86, 89). Recent work has involved linking nitrofuran to various heteroaromatic rings either directly or through one or more ethylene units. 3-(5'-Nitro2'-fUryl)-1,2,4oxadiazoles and thiadiazoles and 2-(nitrofury1)thiazoles were found low in activity in vitro and "largely ineffectivev in animals (90)while the 1,3,4-isamers and 4-(nitro 1)thiazoles reported earlier were active in vivo (many at max. tol. doses Hydroxymethyl- and bishydroxymethyl-amino derivatives(g1) are less active and less toxic acutely than the parent known nitrofbylvinyl-aminoheterocycles. It is stated that in vitro activity is increased by insertion of vinyl or substituted vinyl between the 5-nitro-2-furyl unit and a pyridazine or thiadiazole(92), oxadiazole(93, 94), quinoline(g5), pyridine(96) and its l-oxl&?(97), range of minimal inhibitory concentration6 being 0.03 to lOmcg/ml. The insertion of another vinyl group is claimed to increase the in vitro activity still W h e r for oxadiazoles(98) and pyrimidines(gg), range of m.i.c. 0.02 to O.%cg/ml. Several were found active in vivo but only at maximum tolerated doses. 3-( beta-Substituted ethyl)-1-( 5'-nitro-2'-~furylideneamino)-imidazolidin-2-ones are claimed(100) to be more active in vivo but less active in vitro than the 3-H parent(101).

r

E%5T,

7.

122

Sect. I11

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Chemotherapeutics

F l y n n , Ed.

Antileprotic Agents.--Although the age of chemotherapy has benefitted its treatment, the effect on this wide-spread(lW) disease is incomplete and slaw. The slowness is befitting this, the most ancient infectious disease of man, which has the longest known incubation period (from 3 to 8 or more years) and the longest generation time (30 dws)(l(X?, 103). New agents have come from trying in human leprosy anything active against tuberculosis, hoping for activity on the basis of the taxonomic relationship of the causative organisms. Neither an in vitro test nor an experimental form of the disease has been available but recent advances have been made(lOe, 103, 104, 105). Although some antituberculotics are effective against human leprosy, activity against tuberculosis is an unreliable indicator(l06) of humin antileprotic activity, and vice versa. Three reports of activity have come from clinical use of agents available for widely differing purposes. ~li~de(cCphthalimidoglutarimide),while being employed as a sedative, showed activity against human lepromatous leprosy in 6 consecutive cases by several criteria. It will be interesting to await confirmation of this preliminary report(107). In another preliminary report(108) involving a more extensive trial(50 patients) in a controlled comparison with diaminodiphenylsulfone, ethambutol was reported equally active. Against an experimental Wco. lepraemurium infection(109) in mice it was estimated to be s o m e a t less active than the sulfone. &re active than this standard in the murine infection are Lsulfa-6-methoxypyrimidine and 3-sulfa-6-methoxypyridazine. Several papers on clinical ficacy of the latter have appeared(ll0, 111). Using the murine test, 1$44- ubstituted phenyl or pyridyl)-5,6,7,8-tetrahydro-l-naphthyltuninopropyiJ piperidines were found to have an interesting level of activity(ll2). In Vitro Actives.-Such compounds are potentially useful for bacterial control of body cavities, genitourinary tract, wounds, skin prior to operations, hands of medical personnel, and for preservation of parenteral and topical~dicinals. The significance of many publications can not be judged since tests are not adequately defined or related to standards nor are toxicity, in vivo results and effect of protein on activity given. The following were active against Gram-positive and Gram-negative organisms at the minimal inhibitory concentrations given: 6-( 4t-methoxyphenyl)-Mdazo @, at 8-60, 2-(phenyl and 2' -pyridyl)-isatogen( 114) at 25-200, -2-(dichloroacetyl)guanidine(ll5) at 0.05-25, and 3-(methyl and ethyl)-l-hydroxy-2-oxoquinoline(116) at 0.3-5mcg/ml. In the latter which is 1-10 times as active as aspergillic acid, the hydroxamic acid moiety is necessary but not sufficient for activity. Dibenziodolium(ll7, 118) and dibenzoxaiodinium analogs(119) were claimed to be more stable and more active (m. i. c. 0.3-25mcg/ml) than the diphenyliodonium analogs; acute LD50 10-

1-d

1oow/kg.

Work continues on detergent bases and cationic surfactants, whose activity was first reported in 1935. Antibacterials of this kind generally inhibit both Gram-positive and Gram-negative organisms. 2-(N-Decylpyrrolidinium) ethyl trans-beta-(l-naphthyl)acrylate(l20) was 50-100-fold less active in the presence of serum, an effect common to many agents of this class. Other compounds active were polychloro-2,3-diphenylpropylamines( 121) and 3,3,3tris(4' -chlorophenyl)propyl-N,N-bis(beta-pyridinium ethy1)amine dichloride at l-lOOmCg/ml. Several kinds of phenylenebis (4-amino-6-amidinoquinainoquines (122) were active at the same concentration but were not active in vivo. The activity of N-( 3-phenyl-2-propyl)-3,3-diphenylpropylamine( 123) at l-lOmcg/ml

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against Gram-positive organisms is reversed by nucleic acids or by divalent cations. The latter also antagonized the action of steroidal tertiary amines or quaternaries(l24) whose cellular damage is prevented by spermine also. 5-Azacytidine at 0.2mcg/ml inhibits growth of E. coli as a result of spontaneous triazine ring-opening in the nucleic acid into which it is incorporated( 125). Mono and di-chloro Z-benzamido-4,6-dialkoxypyrimidines (126) inhibited Staph. aureus at l-5mcg/ml but the somewhat more active Lsulfa-2, 6-dimethoxypyrimidine standard inhibited Gram-negative organisms also. Their activity may be a variant of the halo-salicylanilide type(l27). 2,bDialkanoyl phloroglucinols( 128) also have narrow spectra(Staph. and Strep. inhibition at 0.1-0.5 mcg/ml); related resacetophenones are inactive(129). A rela tively unstable chelate permits cell penetration by salicylaldehydes whose activity against Pseud. aeruginosa is dependent on the amount of free aldehyde group liberated inside the cells(l29). This organism is subject to bactericidal action (130) by ethylenediaminetetraacetic acid but not other chelators; it produces damage to the protoplast membrane. Research Techniques and Screening &tho&.-Radioactive tracers have been used in studying pharmacology and mechanism of action. The primary antibacterial action of nalidixic acid was shown(47, 48) to b specific inhibition of DNA synthesis by following the incorporation of lEC- and 3H- labeled purines, pyrimidines and amino acids into DNA, RNA and protein of E coli. Ethionamid ' 8 mechanism of action was investigated(38) by me s of j2P-, 35S- and lEC- labeled nucleic acid and protein precursors. lg-Ethambutol was e loyed in human pharmacological(20) and mechani.sm of action(l9) studies. lq-Iabeled quinaldinium compounds were used to determine their mechanism of antibacterial action( 131). Pharmacokinetic equations are being solved by analog computers and used (64, 65, 132, 133) to devise optimal dosage regimens which are important to safe, effective clinical trials and can make laboratory comparisons more incisive by equalizing exposure of infections to drugs. These equations have been applied in a series of papers to sulfa drugs(64, 65, 133) for which extensive pk, protein binding, excretion, and distribution data are available. Adequate screening methods for leprosy have been lacking but tissue-culture(102) and in vitro growth(lO5) have been disclosed. Growth of the human strain in cell-free medium has resulted(105) from use of unisolated growth factors from lysed saprophytic mycobacteria. One method available has been the mouse foot-pad growth(103) of Myco. leprae which does not produce a leprosy infection and might be considered a form of tissue-culture. A mco. lepraemurium infection(109) in mice has several similarities to the human disease but also certain differences. According to a recent report(104), the infection of black mice with "Chatterjee" bacilli is not the hoped-for major step forward in antileprotic screening but seems to be a modified M. lepraemurium infection. A lethal Tl3 infection was developed(134) in guinea pigs by intracardial injection of M. tuberculosis H37Rv but has a more variable survkvaltime than the mouse infection and requires more compound for testing. Various kinds of delayed and intermittent treatment of tuberculous mice have been studied(l35) with half a dozen reference drugs. Correlations of molecular vibrations,7%electron energies and of calculated molecular orbital and bond-hybridization character with antibacterial activity(l36, 137, 1-38>139) provide interesting summaries of where one has

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- Chemotherapeutics

F l y n n , Ed.

been rather than where one is going. Perhaps when we know how to transfer in vitro data successfully to in vivo tests, we will be able to make use of such specialized, "unidirectional" theoretical approaches. Modern physical methods and chromatographic techniques are being applied to problems of separation and identification of synthetic antibacterial structures and their metabolites, which in the case of nalidixic acid makes a major contribution to activity: gas chrmtography (14, 140); thin-layer chromatography of sUlfanilamides(l41, lk),amines(143), and heterocycles (144); mass spectrametry of pyrimidines(145) and d s ( 1 4 6 ) ; nmr spectrometry of phenols(147, 148), peptides(l49), and pyrimidines(l50); X-ray spectrompem of P-, s-, and halogen- containing ccarrpounds(l5l.); and --ray spectrof neutron-activated pharmaceuticals(1%) employed in forensic investigations but broader in potential(l53). enzymic bases of now well-defined mechanisms Mechanism Of Action.-The for bacterial control (cmpetitive inhibition of essential enzymes, feed-back inhibition of biosynthesls of the natural competitor, repression of fonnation of a necessary enzyme, and non-competitive inhibition by reacting with the enzyme active center) have been reviewed(l54). The biochemical basis for differential action of an antibacterial toward host and microorganism is clear for a number of synthetic agents(156). Differences in response to dihydrofolate reductase inhibitor6 reflect differences in the structural limitations of the binding site of the same enzyme from different bacteria(l55). Sulfanilamides are unique in having their mode of action almost completely known at the enzyme level. The step in folic acid synthesis at which they intervene has recently been shown to be the reaction of PAB with the pyrophosphate ester of 2-amin0-4-0~0-6-hydro~thyldihydropteridine (155). The sulfa8 are now known to participate in this reaction and form spurious folic acids, but their significance in growth inhibition is not certain. Some differences in responses of bacteria are due-to relative abilities to transport and assimilate folic acid. Sulfanilic acid is an inhibitor of a cell-free enzyme system but not of bacterial growth, presumably due to difficulty with cellular transport(155). Bactericidal action of sodium tetrapropylenebenzenesulfonate resulted. from lysis of protoplast membranes; in contrast to many other agents, this action decreased as cellular metabolic activity increased( 156). Sodium lauryl sulfate produces inhibition of biosynthesis of S. aureus cell walls similar to that produced by penicillin(157). Prevention of emergence in vitro of drug resistance to a variety of antibacterials by spermine or atabrine was reported(l58) to result f r o m preventing induction of resistance. An antimutagenic action of spermine toward random as well as induced mtations(159) confirms the effect (stated not to be co-inhibition) in vitro but demonstration of a ureful effect in vivo is still lacking. Reviews.-Reviews appeared on tuberculosis(15, 29, 160, 161), leprosy( 106), sulfa antgs(63, 64, 65, "7, 79, 1331, nitrofuram(%), drug interaction(76), protein binding(77, 133), mechanisms of action(154, 155, 162), and combinstion therapy( 163). REFEREmCES 1. The mercurial8 used for syphilis in the 1500's might also be considered as the first antibacterials. 2. W. E. Taft, H. M. Krazinski, F. C. Schaefer, and R. G. Shepherd, J. Med. -* 8, 784 (1965).

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Shepherd

3. A. R. Frisk and E. Hultman, 4th Internat. Congr. Chemotherapy, 1965, Washington, D. C., Abstracts, p. 33. 4. D. L. Pain and R. Slack, J. Chem. SOC. (Lond. ) 5166 (1965). 5. P. Schmidt and L. Neipp, Proc. 3rd Internat. C o n g r . Chemotherapy, 1963, Stuttgart, 1355 (1964). 6. G. Siefert, Arzneimittel-Forsch. 9, 1359 (1965). 7. G. R. Gale and J. E. Hawkins, Am. Rev. Resp. D i s . E, 64.2 (1965). 8. P. Mmalis, L. J e f f r i e s , S. A. Price, M. J. R i x , and D. J. Outred, J. Med. Chem. 8, 684 (1965). 9. Editors, Mod. Wd. 32, 54 (1964). 10. I. Ksss, Tubercle ( E d . ) 46, 166 (1965). 11. Conference on New Antitubezulous Agents, Sept. 1965, Ann. N. Y. Acad. Sci. 135, 680-1120 (1966). 12. T F . Corpe and F. A. Blalock, MS. Chest 48, 305 (1965). 13. I. D. Bobrowitz and K. S. Gokulanathan, DiK Chest 48, 239 (1965). 14. J. Po !L'honkasy C. 0. Baughn, R. G. Wilkinson, and R . 3 . Shepherd, Am. Rev. Resp. D i s . 5, 891 (1961); R. G. Wilkinson, M. L. Cantrall, and R. G. Shepherd, J. Meed. Chem. 5, 835 (1962). 15. F. Grumbach, Advan. Tuberc. Res. 2, 74 (1965). 16. S. K O Gupta and I. S. Eilathur, Indian J. Exptl. Biol. 2, 81 (1964). 17. M. Forbes, N. A. Kuck, and E. A. Peets, J. ~acteriol.-89, 1299 (1965). 18. F. Grumbach, Ann. Inst. Fasteur 110, 69 (1966). 19. S. K. Gupta and I. S. Mathur, InJ. E x p t l . Biol. 3, 176 (1965).

20. E. A. Peets, W. M. Sweeney, V. A. Place, and D. A. BU%ke, Am. Rev. Reap. D i s . 91, 51 (1965). 21. J. G.Tolentino, R. S. Quint0 and R. M. Abalos, 25th Res. Conf. i n Pulm. Diseases of VA-Armed Forces, Jan. 1966, Cincinnati, Ohio. 22. Y. T. Chang, Antimicrobial Agents Chemotherapy 777 (1965). 23. Editors, B r i t . Med. J. 1(5449), 1508 (1965). 24. M. Olejnicek, M. Weberova, M. Novak, and E. Jancik, Tubercle (Lond.)

1964,

188 (1965).

5,

25. A. S. Moodie, M. Aquinas, and R. D. Foord, Tubercle (Lond.) G , 1% (1964). 26. S. Sunahara, Tubercle (Lond.) 46, 178 (1965). 27. Editors, Tubercle (Lond.) 46, 8 8 (1965). 28. G. Meissner, Praxis h e w r 19, 387 (1965). 29. F. Grumbach, Advan. Tuberc. R G . 14, 70 (1965). 30. M. Boszormenyi, I. Fauszt, I. B ,* and 0. Schweiger, Tubercle (Lond.) 46, 143 (1965). 31.

J.M.

Schless, R. F. Allison, R. M. Inglis, E. F. White, and S. Topperman,

Am. Rev. Resp. Die. 91, 728 (1965). 32. F. I t o and K. HayanoTAm. Rev. Resp. Ms. 91, 796 (1965). 33. A. W. Lees, B r i t . J. D i s . Chest 59, 228 (1'965)34. A. Pines, Tubercle (Lond.) 46, l z (1965). 35. I. Kass, Tubercle (Lond.) 4 c 151 (1965).

36. A. W. Lees, Am. Rev. R e s p . 3 8 . 91, 966 (1965). 37. H. Iwainsky, I. Sehrt, and M. G r u n e r t , Arzneimittel-Forsch. 15, 195 (1965). 38. M. T s ~ ~ k a m r aIgaku , To Seibutsugaku 67, 80 (1963); Chem. Absc. 63, 12024f (1965). 39. H. Hartwlgk, Tuberculosearzt 9, 522 (1965).

40. S. Oka, J. Konno, M. Kudo, K. Oiztani, and S. Yamaguchi, Am. Rev. Resp. D i s .

41.

919 638 (1965). Verbist, 4th Internat. Congr. Chemotherapy, 1965, Washington, D, Abstracts, p. 60.

C.,

126

Sect. I11 - Chemotherapeutics

F l y n n , Ed.

42. L. Tnka, J. K u s k a , and A. Havel, Chemtherapia 9, 158, 168 (1965). 43. G. Y. Lesher, Proc. 3rd Internat. Congr. ChemothS02NHCONHR R2 I1

R2

wS02N I11

X = CH2, N, 0, S R = alkyl, cycloalkyl and haloalkyl R1 and R2 = alkyl and alkoxy this series among the same alkylurea substituents (R) that give maximum activity in the sulfonylureas. The corresponding sulfamyl semicarba~ides~~ also had significant hypoglycemic activity as did a few of the related sulfamylcarbamates.65 Compounds in which the alkylurea portion was derived from a secondary amine, usually heterocyclic, were, in general, less activeP5 A number of the compounds were as active (reduction of blood glucose in fasted rats) as chlorpropamide. Further details of the pharmacology of the sulfamylureas have not been reported, but it seems safe to assume that their mechanism of hypoglycemic action would be very similar to that of the sulfonylureas. Several of the compounds are stated to show hypoglycemic activity in man but their clinical use in the management of diabetes has not been reported.

170 -

Sect.

IV

-

Metabolic & Endocrine

H e i n z e l m a n , Ed.

This work made good use of the now firmly established correlation, among compounds of this class, of hypoglycemic action with the presence of the compounds in the blood. Synthesis was therefore guided not only by the relationship established between structure and acute hypoglycemic activity, but also by an evolving concept of the influence of physical and chemical properties on absorption, metabolism and excretion, derived from a concurrent investigation.66 The metabolism and excretion of 15 of the compounds were determined in dogs and seven were studied in human subjects. The results of these studies were correlated with physical and chemical properties, of which pKa and lipid-water partition ratio proved to be the most useful. 0 he variants on the sulfonylurea structure have recently included and 2-cyanop-alkenyl-,679 2-acyl- ,69 E-a1koxyalkyl - ,69 E-haloalkyl , as well as 6-s~lfamoylbenzotriazole,~~ benzenesulfonyl-69 6-sulfamoylben~imidazole~~ and 5-indanylsulfonyl70 derivatives. A variety of alkyland aralkylurea71 substituents have been combined with these as well as with the now conventional benzenesulfonyl moieties. A series of compounds in which the urea function was part of a benzimidazolinone ring were devoid of hypog 1 ycemic activity .72

h

-

'

A sulfonarnidothiadiazole very similar to the sulfonamide that started it all has been reported to reduce blood sugar in alloxan diabetic rats, but the experiment was not controlled with a known ~ulfonylurea.7~ Considering its structural similarity to the earlier compound, incomplete alloxanization appears a likely explanation of this result.

Pharmacolom, Mechanism of Action. The pharmacology of the sulfonylureas has been reviewed recently.74~10

It is now almost universally accepted that the primary action of the sulfonylureas is to release insulin from the pancreatic b-cells. Overwhelming evidence indicates that the drugs have no significant hypoglycemic effect in animals or human diabetics who are without functioning @-cells. The details of the process by which the sulfonylureas release insulin, however, remain as much a mystery as the process by which glucose produces the same effect. A vast amount of evidence has been marshalled against the view that the sulfonylureas affect hepatic glucose output or peripheral glucose utilization except through insulin release, but the uestion of a direct effect on the liver has not been entirely re~olved.~?There have been suggestions that sulfonylureas affect the plasma factors that influence insulin action (see above) but the significance of the effect to their hypoglycemic action remains to be assessed.76 It has long been recognized that the hypoglycemic effect of the sulfonylureas is related to their concentration in the blood.77 A s with many acidic drugs, plasma half life is a key determinant of overall effect79 and studies of their physiological disposition have proved to be important in guiding their clinical use.59,78 The metabolism of tolbutamide and chlorpropamide has been reviewed.74 The metabolism of glycodiazine ( lasma half life, 3.5-4 hr. )80,81 and tolazamide (plasma half-life, 7 hrs.) 85 has been studied in human subjects.

Chap. 15

Antidiabetics

Pinson

171 -

From the point of view of metabolism, acetohexamide is the most interesting of the sulfonylureas. Although its plasma half-life is short ( 1 . 3 hrs.), it is reduced in the body to a metabolite, L(-)-hydroxyhexamide, which is not only more active (2-2.4 times acetohexamide), but is also longer lasting (half-life, 4.6 hrs. ).82,83 The net result is that hypoglycemic activity in the blood, which is due to acetohexamide and the metabolite, persists for about the same length of time as it does with tolbutamide. The fact that the metabolite is at least twice as active as the racemic form of the compound would imply that the D(+) form is essentially inactive, which seems incredible, considering how widely significant activity is found among the sulfonylureas. Unfortunately, synthesis of the compound has not yet been reported. Other metabolites of acetohexamide, which are essentially inactive as hypoglycemic agents, result from hydroxylation in the cyclohexyl g roup .83 The importance of solubility, and of solution rate, as a function of surface area, to rate of intestinal absor tion and hence to the time course of blood levels has been i n ~ e s t i g a t e d . ~ ~ , ~ ~ , ' ~Proper ,~~ consideration of these factors in dosage form preparation can be important determinants of overall efficacy.84 Binurnides The biguanides are widely used in the control of diabetes; phenethylbiguanide (phenformin, DBI, Dibotin) in the United States, and, in addition, butylbiguanide (buformin, Silubin) and N,N-dimethylbiguanide (metformin, Glucophage) in Europe. Their principal clinical application is in combination with sulfonylureas for the treatment of patients whose disease is poorly controlled on either agent alone and for smoothing the hypoglycemic response of insulin-dependent brittle diabetic^.^',^^ Few new compounds of the class have been reported recently, but a series of aralkylamino, aryloxyalkylamino, and arylthioalkylamino-s-triazines (V) designed from consideration of the structure of the biguanides when written in the cyclic, hydrogen bonded form (IV) has been prepared. The compounds had only weak hypoglycemic activity in rabbits.89

IV

V

Pharmacolop;y,Mechanism of Action. The mechanism of biguanide induced hypoglycemia has still not been established. Different investigators cannot yet agree on which of the many effects that have been observed in experimental systems are responsible for their clinical action The roblem has been reviewed and discussed from several points of view.74,90,9P,92,93 It seems clear that glucose utilization by anaerobic glycolysis is increased, the further metabolism of the resulting pyruvate is inhibited, and lactate

172

Sect. EV

-



t h e r e f o r e accumulates. T h i s i m p l i e s a n a c c e l e r a t i o n of a n a e r o b i c g l y c o l y s i s r e s u l t i n g from a r e d u c t i o n of o x i d a t i v e metabolic a c t i v i t y ; an e f f e c t f i r s t d e s c r i b e d by P a s t e u r and s i n c e known as t h e P a s t e u r e f f e c t , which Randie52 From t h e work of Passonneau and now p r e f e r s t o c a l l " r e s p i r a t o r y c o n t r o l " . LowryYg4P a r k l 3 and h i s co-workers ar,d Randleg5 and h i s associates, t h e mechanism of t h i s e f f e c t i s now understood i n some d e t a i l . A thorough d i s c u s s i o n of t h e s e c o n c e p t s i s c o n t a i n e d i n R a n d l e ' s review.52 Phenformin h a s been shown t o i n h i b i t some m i t o c h o n d r i a l e l e c t r o n t r a n s f e r r e a c t i o n s and t h i s h a s been suggested as i t s primary s i t e of a c t i o n . 9 0 S e v e r a l o b j e c t t o n s t o t h i s h y p o t h e s i s have been r a i s e d , however. F i r s t , t h e concentrations required t o i n h i b i t mitochondrial oxidation & I n view of v i t r o are much h i g h e r than have e v e r been observed i n t h e f r e q u e n t d i s p a r i t y between i n v i t r o and i n v i v o r e s u l t s and problems of t i s s u e and s p e c i e s s e n s i t i v i t y , t h i s o b j e c t i o n i s n o t , of i t s e l f , p a r t i c u l a r t h a t c l o s e l y r e l a t e d hypoglycemic l y s e r i o u s . However, a second o b j e c t i o n b i g u a n i d e s show a similar hypoglycemic e f f e c t but do n o t i n h i b i t m i t o c h o n d r i a l o x i d a t i o n , whereas o t h e r s , which are devoid of hypoglycemic a c t i v i t y , are n e v e r t h e l e s s p o t e n t i n h i b i t o r s of m i t o c h o n d r i a l e l e c t r o n t r a n s f e r r e a c t i o n s g 7 -- d e s e r v e s c a r e f u l c o n s i d e r a t i o n . T h i r d , i t h a s been shown t h a t low conc e n t r a t i o n s of buformin ( 1 - 5 p g / m l ) , which are i n t h e range a t t a i n e d i n v i v o , a c t u a l l y i n c r e a s e t h e a c t i v i t y o f t h e p e n t o s e shunt i n a d i p o s e t i s s u e and t h i s i s c i t e d as e v i d e n c e t h a t t h e hypoglycemic a c t i v i t y of t h e b i g u a n i d e s does n o t i n v o l v e i n h i b i t i o n of o x i d a t i v e p r o ~ e s s e s . 9 ~The c o n c l u s i o n t h a t o x i d a t i v e metabolism i s n o t i n h i b i t e d seems u n t e n a b l e , c o n s i d e r i n g t h a t hypoglycemic d o s e s of phenformin i n v a r i a b l y c a u s e i n c r e a s e s i n blood and u r i n a r y l a c t i c a c i d and t h a t p y r u v a t e t o l e r a n c e i s decreased.98 The buformin e f f e c t on a d i p o s e t i s s u e i s v e r y similar t o t h e e f f e c t of epinephrine99 and, cons i d e r i n g t h e r e a s o n a b l e s t r u c t u r a l analogy between buformin and t h e a l i p h a t i c p r e s s o r amines, may r e s u l t by a similar mechanism.

--

One of t h e most p e r t i n e n t i n v e s t i g a t i o n s of t h e e f f e c t of phenformin on metabolism i s t h a t of Williamson, Walker and Renold.lOO Using t h e i s o l a t e d p e r f u s e d rat h e a r t , t h e y found s u b s t a n t i a l i n c r e a s e s i n g l u c o s e u p t a k e and l a c t a t e f o r m a t i o n and d e c r e a s e d i n t r a c e l l u l a r ATP a t phenformin c o n c e n t r a t i o n s of 3 5 - 5 0 Gg/ml. The a u t h o r s i n t e r p r e t t h e s e f i n d i n g s i n t h e l i g h t of c u r r e n t c o n c e p t s of n e u c l e o t i d e and phosphate feedback c o n t r o l of p h o s p h o f r u c t o k i n a s e , a s t h e rate c o n t r o l l i n g s t e p of g l y c o l y s i s , a n d f u r t h e r s u g g e s t p o s s i b l e i n h i b i t i o n of p y r u v a t e d e c a r b o x y l a t i o n . Like many i n v e s t i g a t o r s of t h e b i g u a n i d e s , Williamson, Walker and Renold d i s c o u n t t h e r e l e v a n c e of t h e i r r e s u l t s t o t h e c l i n i c a l s i t u a t i o n because of t h e r e l a t i v e l y h i g h drug c o n c e n t r a t i o n s used. Such d i f f e r e n c e s seem much less i m p o r t a n t i f one c o n s i d e r s p o s s i b l e t i s s u e and s p e c i e s s e n s i t i v i t y . The rat i s remarkably i n s e n s i t i v e t o phenformin, showing l i t t l e hypoglycemic e f f e c t at 80 m /kg 101 It w h i l e human d i a b e t i c s respond w e l l a t d o s e s of 50-150 mg ( 1 - 2 mg/kg).'8 h a s been p o i n t e d o u t t h a t an a d d i t i o n a l component of hypoglycemic a c t i o n probably r e s u l t s from impairment of t h e r e c o n v e r s i o n of lactate, formed i n The i n h i b i t i o n o f p y r u v a t e decarboxylmuscle, t o g l u c o s e i n t h e liver.90,102 a t i o n mentioned above would a c c o r d w i t h t h e d e c r e a s e d l i o g e n e s i s t h a t h a s been suggested by r e c e n t c l i n i c a l o b s e r v a t i o n s ,103,104,1g5 s i n c e reduced a v a i l a b i l i t y of a c e t y l CoA would be expected t o i m p a i r l i p i d s y n t h e s i s . T h i s a s p e c t of t h e a c t i o n of t h e b i g u a n i d e s does n o t a p p e a r t o have been s t u d i e d

Chap. 15

173 -

Pinson

Antidiabetic s

directly. The possibility of a direct action of the biguanides on adenyl cyclase to cause cyclic 3',5'-AMP activation of phosphofructokinase has not apparently been considered but it is an intriguing one. Although cyclic 3',5'-MP is known to activate mammalian phosphofructokinase, a hormonal effect through adenylcyclase stimulation has not yet been demonstrated.Io6 Y 125 The interesting enigma that the biguanides do not cause hypoglycemia in non-diabetic individuals has received some clarification recently.lo7 Glucose turnover studies in non-diabetic human subjects have shown that glucose utilization is markedly increased but that hypoglycemia does not occur, apparently because the increased utilization is offset by a corresponding increase in glucose output from the liver. It seems reasonable to suggest that an effect on hepatic glucose output is the key difference, in this respect, between diabetics and non-diabetics. Hepatic glucose out ut in diabetics comes mainly from gluconeogenesis, which phenformin inhibits;f02 whereas the hepatic glucose output of non-diabeti.:s, under the conditions of this experiment, would come primarily from glycogmolysis, which phenformin accelerates.90 The distribution, metabolism, and excretion of henformin, metformin and buformin have been investigated.lo8, log ,llo,11'1 The physiological disposition of the biguanides is typical of that of other strong organic bases. The compounds diffuse from the blood, where concentrations are invariably low and not very persistent, into acidic gastric juice, are found in higher concentrations in tissue than in the blood, and are eliminated efficiently in the urine. The identity of their metabolites has not been established with certainty. Other Hypoglycemic Compounds Pyrazoles and Isoxazoles. Since 1963, a series of reports have described two interesting hypoglycemic and lipolysis inhibitin corn ounds, 3,5-dimethylpyrazole (VI) ana 3,5-dimethylisoxazole (VII).112,~13,1p4,115

CH3

pcH3 CH3

CH3

H

VI

VII

HOOC

(flCH3 N/

H

VIII

HOGC (flCH3 O N IX

Both compounds are remarkably potent hypoglycemic agents (50 and 200 times as active as tolbutamide) in glucose primed rats but are much less active in fasted animals. Both are apparently inactive, themselves, but depend for activity on metabolism to 3 -methylpyrazole-5-carboxylic acid (VIlI) and 3methylis0xaz0l~~5-carboxylic acid (IX), respectively.116,11' Although the carboxylic acid is a relatively minor metabolite of dimethylpyrazole (10-15% in the rat), it apparently accounts for all of the activity. The major metabolite, 4-hydroxy-3 5-dimethylpyrazole (70-75% in the rat) shows no hypoglycemic activity.li7 The two carboxylic acids are potent inhibitors of the release of free fatty acids from adipose tissue and the authors make the reasonable suggestion that this is their primary action, from which the hypoglycemic effect r e s ~ l t s . ~ The ~ ~ mechanism . ~ ~ ~ by which inhibition of

174

Sect. IV

-



lipolysis might promote glucose utilization has been discussed extensively by Randle,48 and these compounds might well be used in further examination of some of his hypotheses. 5-Methylpyrazole-3-carboxylicacid was effective in reducing the plasma free fatty acid levels of fasted human subjects118 but the concomitant effect, if any, on their blood glucose was not reported. None of a series of pyrazole congeners of 3,s-dimethylpyrazole was apparently more active than the parent compound.120 L-Leucine. The subject of leucine induced hypoglycemia, which occurs in certain sensitive individuals, particularly some children with "idiopathic hypoglycemia'' and patients with functioning islet cell tumors, has been very ably reviewed recently by Fajans.l*I Addition of L-leucine (12 g/day) to the regimen of sulfonylurea secondary failures resulted in good diabetic control in 8 o f 10 patients.122

A series of hexahydroindenio[1,2-~]pyrrols and indanamines have been reported to reduce the blood glucose of orally treated rabbits but details that might permit an assessment of their potential as oral antidiabetic agents are lackirg.123 References 1. 2. 3. 4. 5.

6.

I. 8. 9. 10. 11. 12. 13. 14. 15 * 16.

11. 18. 19. 20. 21.

22. 23.

M. Janbon. J. Chaptal, A. Vedel, and J. Schaap, lontpelller Meed.. 21-22, 441 (1942). 253 (1918). C. K. Watanabe, J. Biol. Chem., P. White. led. Clin. I. An.. 3. 855 (1965). A. E. Renold and 0 . F. Cahill, Jr. in "The Metabolic Basis of Inherited Disease", 2nd Ed., J. B. Stanbury, J. B. Wynngaarden and D. S. Fredrickson. Eds., lcQrau-H111 Book Co., leu York, 1965. B. S. Leibel and 0. A. Wrenshall, Lds. "On the Uature and Treahent of Diabetes", Sxcerpta ledloa Foundation. Xeu York, 1965. R. H. Williams and F. C. Wood. Jr., Reference 5. Chapter 51. -R. II. Williams. Ann. Intern. led., 63, 512 (1965). S. A. Berson and R. A . Yalou. Diabetes, 14. 549 (1965). 0 . F. Cahill. Jr. led. Clin. x. An., 49. 881 (1965). 0. M. Orodsky and P. H. Forsham. Ann. Rev. Physiol.. g.341 (1966). P. P. Lacy. C l b a Found. Collos. Xndoorlnol., 15,15 (1964). S. E. Brolin. B. Hellran and 8 . Knutson. Eds. "The Structure and Metabolism of the Pancreatic Islets", Pergaron Press, !Jew York, 1964. H. P. Morgan. J. R. Xeelg. R. P. Wood, C. Llebecq. €I Liebermeister . and C. 8 . Park, Federation Proc.. 24, 1040 (1965). R. Levine. 1011. I. 0. Wool, 1060. D. X. Klpnl8 and J. E. Parrish, E .1051. J. S. Bishop, R. Steele, I. Altszuler, A. Dunn, C. Bjerknes and R. C. de &do. Physiol.. 208, 301 (1965). Q. Weber and 1. L. Singhal. Life Scl.. 2, 1993 (1965). A. Sols, Reference 5. Chapter 9. D. 1. Klpnis and R. Hallchoff, J. Clin. Invest., 44. 1064 (1965). A. Oellhorn and W. Benjamin. Science, 148,1166 (1964). D. R. Rampersad and I. 0 . Wool, Science, 149, 1102 (1965). E. Sprols. Reference 5, Chapter 16.

a,

s.

s.

uJ.

Chap. 15

Antidiabetic s

Pinson

175 -

24. D. H. Lockwood and T. X. Prout, Uetab. Clin. -2.. l4, 530 (1965). 25. B. H. Segal, Uetab. Clin. XQ 758 (1964). 26. S. H. Oershoff. A. 1. Huber and B. H. Antonlades, Uetab. Clin. Q.. g ,325 (1966). 27. H. H . Antonlades. A. U. Huber. B. R. Boshell. C. A. Saravis and S. Y. Oershoff,

.,s,

28.

29. 30. 31. 32. 33. 34.

35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49 * 50.

51. 52. 53. 54.

55. 56. 57. 58.

59. 60. 61. 62. 63. 64. 65.

a

Xndocrinoloa. 709 (1965). 1. Samaan, J. Brown, R. Fraser and I. Trayner, Brit. Hed. J.. 1965(1), 1153. T. Welborn, I?. Samaan, R. Fraser and J. Brown. Mabetologla. 1, 74 (1965). B. R . Froesch, H. Burg1 and U. S. Uuller, Helv. Xed. Acts.. 2, 341 (1965). Q . F. Cahlll. Jr., V. Laurls, J. S. Soeldner, D. Slone and J. Steinke. Btab. c u 769 (1964). J. Steinke, S . Uikio and 0 . F. Cahill, Jr., Yew pllg. J. Hed.. 273, 1464 (1965). J. K. Davidson, B. E. Haist and C. H. Best, Diabetes, 12, 448 (1963). L. Power, C. Lucas, and J. Is. Conn. Hetab. Clin. Exp.. l4. 945 (1965). W. 1. Shaw in "Adipose Tissue", A. E. Renold and 0. F. Cahlll. Jr., Pds., Handbook of Phusiologg, Section 5. American Physiological Society. Washington, 1965. J. Vallance-Owen, Reference 5, Chapter 23. H. Alp and L. Recant, 3. Clin. Invest., 44, 870 (1965). U. L. Ashton. J. fndocrinol., 33, 103 (1965). J. U. Xnsinck, R . J. Mahler and J. Vallance-Owen, Blocher J., 2.150 (1965). R. L. Fenichel. W. H. Bechrann, and H. 11. Alburn. Biochemistry, 5 , 461 (1966). I). 1. Kipnis, Reference 5 . Chapter 18. R. C. Haynes, J r . , Advan. X n m e Regulation. 2, 111 (1965). A. B. Xisenstein, 121. X. Y. Sutherland and 0. A. Robison, Pharmacol. Rev., Is,145 (1966). A. 0. Kris. R. L. Xlller, F. P. Wherry and J. Y. Wason, Pndocrinoloeg!. 3, 87 (1966). D. Porte, Jr., A . Oraber. T. Kuzuya and R. H . Uilllans. J. Clin. Invest., &%1087 . (1965) D. Steinberg, Pharmacol. Rev., 18,217 (1966). P. J. Randle. Reference 5. Chapter 25. Pharmacol. lev., B, 145-314 (1966). U. S. Ooldstein, An. J. Physiol., 200, 67 (1961). X. S. Ooldstein. Paderation Proc., 2,441 (1966). P. J. Randle in "HOmeOltaSil)and Feedback Uechanlsms", Society for mperirantal Biology Synposia XVIII. Academic Press Inc., Yew York, 1964. p. 129-156. A. X. Renold and 0 . F. Cahill. Jr., "Adipose Tissue", Handbook of Physiology, Section 5. American Physiological Society, Washington. D. C., 1965. A. P. Renold, 0. B. Cmfford, U. Stauffacher and B. Jearenaud, Mabetologla, 1,4 (1965). J. P. Flatt and P. 6. -11, Reference 53, Chapter 26. H. S. Kornacker and P. 0. Ball, $roc. Hat. Acad. ScI. 0. S., 54. 899 (1965). The preparation of glycodiazine and a number of analogs, with Its PhaFlaColOgJr, metabolism and clinical use deacrlbed in a. series of 10 papers; Arzneirittel-Forsch.. 14. 373 (1964). R. D. H. Stewart and D. X. Anderson, Brit. Hed. J., 1965(21. 682. F . Q. XcUahon. H. L. Upjohn, 0. S. Carpenter, J. B. Wright. H. L. Oster, and U. X. Dulln. Current ,.-T 2, 330 (1962). R. Bressler and R. Katz, Current Therap. Res., 1, 219 (1965). P. H. Orinnell, T. 0. Skillman, R. Barse. and C. L. Holler, Current them^. Res.. 2, 433 (1964). Federal Register, 2,2561 (1966). J. H. UcUanus, J. W. HcFarland, C. P. Oerber. W. U. UcLaPore, and 0 . D. Laubach. J. led. Cher.. 8 , 766 (1965). J. 1. 1cwSnus and C. F . Oerber. J. Ued. Chem., 2, 256 (1966). J. W. UcFarland. C. P. Qerber. and Y. 1. XcLarore, J. Had. Chu.. 2. 781 (1965).

s., 13.

u..

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Sect. I V

176 66. 61. 68. 69. 10. 71. 72. 13. 14.

75. 76.

11. 78. 19. 80. 81. 82. 83. 84. 85. 86. 81. 88. 89. 90. 91. 92.

93. 94. 95. 96. 91. 98. 99. 100. 101. 102. 103. 104. 105. 106. 101. 108. 109.

- Metabolic

& Endocrine


E. H. Wiseman. J. 1. Perelm, K. F. Pingor, and R. Plmon. J. Ned. m.,4, 771 (1965). D. P. Hayman. 0 . B. Jackman, V. Petrow, 0 . Stephewon. and A. 1. Wild, J. P h a m . Phamacol., 677 (1964). D. P. H a m , V. Petrow, and 0 . Stephanron, J. P h a m . Pharucol., Is. 538 (1964). J. Lederer, J. Ned. Cham., 2, 370 (1064). L. J. L o n e r DA. Blanahi, an8 A. Borron. Hetab. Clln. Un., 578 (1965). K. 0 . Jo8hl and J. 9. h p t a , J. 1ndi.n Chm. Soc.. g,320 (1965). J. B. Wright, J. Bb8, Cham., g, 589 (1965). D. Bargeton, J . Roquet, A. Rouquer. A. CROrsaIn, and A. Bledar, Aroh. Intern. phamacodmamie, 185,319 (1965). L. J. P. Duncan and B. F. Clarke, Ana. Rev. Pharucol., S, 151 (1966). A. R. Colwell, Metab. Clln. -2.. 13, 1312 (1964). 8. 1. htOkIla8e8, J. A. Borrp.8. R. ~ r l ~ - D . r a l o rH., 1. Pyle, S. J. Naturkle, 0 . Low-Castaneda, and A. Narble, New -1. J. md., 269. 386 (1963). K. N. Wort and P. C. Johawon, Mabetor, 2. 464 (1960). J . Sheldon, J. h8er8on. and L. Stoner. Diabetes. 362 (1965). B. It. Bloar and 0 . D. loubach. Ann. Rev. PharrPcol., 2, 61 (1962). K. 8. Kolb. 1. KraMr. and P. X. Schulre. Arzneirittel-Forsch.. 385 (1964). L. Oerhardr, H. 01bI.n. and K . H. Kolb, Armeirittel-Fonch., 2, m4 (1964). D. 1. Smlth, T. J. Veochio, and A. A. F0ri.t. Netab. Clln. Up., 2, 229 (1965). R. 1. HcNahon. F. J. Narshall, and H. W. Culp, J. P w o o l . U p . Therap., 272 (1965). P. ielson, X. I. Knoeahel, W. X. Hailin, and J . 0 . Wagner, J. P U N . s o l . , 2,509 (1962). X. Nelson, S. Long, and J. 0 . Wagner, J. Pham. S o l . , 53, 1224 (19M). W. I. Higuchi, 1. A. Nlr, A. P. Parker, and W. P. Hailin, J. Pham. S o l . , 54, 8 (1965) J . I. bodman, Xetab. Clin. Un.. 14. 1153 (1965). B. P. Clarke and J. P. Duncan, Lancet, 1966(11, 1248. If. Suter and H. Zutter, Helv. Chim. Acta, 48, 1940 (1965). D. P. Stainer an8 R. H. W l l l i o r s , Mabetar, 8, 154 (1959). H. Dnweke and I. Bach. netab. Clin. UP., l2. 319 (1963). J. Sterna, Netab. Clln. UE..2,191 (1964). 1. Beckmann, Deut. mod. Wochschr.. 90. 1589 (1965). J. V. P a 8 8 O Z U l ~ Uand 0. H. L O W . 1,10 (1962). P. B. Oarland and P. J. llPndle. Blochea. J., 93. 678 (1964). A. B. Falcone, R. L. llao and X. Shrago. J . Blol. Cham.. 237, 904 (1962). Q. Ungar, 5 . PSYChoYO8, and H. A. H a l l , Netab. Clln. U p . . 2, 36 (1960). S. S. Fajans, J . A . Xoorehouse, H. Doorenbos. L. H. Louis, and J. W. COM, Diabetes. 9, 194 (1960). 0 . P. Cahill. Jr.. B. Leboeuf, an8 It. B. Fllnn. J. Biol. Chem., 235. 1246 (1960). J. R. Ullllorson. 1. 5 . Walker and A. E. Itenold, Metab. Clln. an..l2, 1141 (1963). 0 . Wwr. L. Freedman an8 9 . L. Shaplro. Proc. 900. U p . B l o l . ned., 95, 190 (1951). S. J. Patrick, Can. J. bloc her.,^, 27 (1966). D. P. Patel and J. 1. Stowerr, Lancet, l 9 6 4 ( 2 ~ ,282. J. Sch-rtg, s. N l r s k y . and L. X. Schaefer, Lancet, 19SS(ll, 959. J. Pedarren, Acta Xndoorlnol.. 49, 419 (1966). T. X. npmoar. P b u v c o l . Rev., 2,173 (1966). 0 . 1. Searle, 9. Schilling, D. Porte. J. Barbacoia, J . DoQmeia. and 1. ti. Cavalieri, Diabetes. l5. 113 (1966). A - 1-Wicklr.c. J. Stewart. and 0 . 5 . S e r i f , Mabetes. 2. 163 (1960). R. -0kMAn. 0 . Hwbner. Arznoinittel-Forsch., 5 . l, 165 (1965).

Is.

s,

z,

z.

xD

,.-

-

*.

Chap. 15 110. 111. 112. 113. 114. 116.

Ant idiabe tic s

Pinson

177 -

R. BeckroM, Arzneirittel-Forsoh.. 18, 761 (1965). Q. Debry and F . P. Cherrler. Theraple. 2.352 (1965). U. 1. Dulln and 0. C. Oerrltsen, Proc. Soo. PD. Blol. Ned.. 113,683 (1963). 0 . C. Oerrltsen and W. 1. Dulln. Diabetes. & 507 (1965). A . B1r;zI. A. Jorl, 1. Veneronl. and S. Oarattint, Life Solences, 3, 1371 (1964). W. 1. Dulln, 0. H. Lund, and 0. 0. Qerrltsen, Proo. Soe. ZXP. Biol. Ned., 118,

499 (1965). 116. D. L. Slrlth, A. A. lOrl5t. and W. 1. Dulln, J. Hod. Chsr., S, 350 (1965). Therap., 150, 316 117. D. L. Slith, A . A. Forist, 0 . C. Oerrltsen. J. Pharmaool. PD. (1966). 118. 0. C. Oerrltsen and W. 1. Dulln, J. Phosrpcol. P p . Therap., 160, 491 (1965). 119. Y. 1. Dulln and 0. C. Oerrltsen, Proo. Soo. P p . Blol. Ned., 121. 777 (1966). 120. J. B. Wright, Y. 1. Dulln, and J. H. I(arklllle, J. Ned. Chem.. 2 , 102 (1964). 12l. 5 . S. FaJaM, New Kml. J. n o d . , 272, 1224 (1965). 122. H. R l f k l n , 5 . Podolsky, H. Ross. X . 0 . Conason, and S. Nost, Mabetes, l5, 222 (1965). 123. S. C. LphlFi a d B. Pathak, J. b d . Ch-., 1, 131 (1966). 124. 1. A. -5i0, J. S. Soeldner and 0. F. Cphlll. Jr., Dlabetologia, 1,125 (1965). 125. R. M. Denton 8nd P. J. Ilurdle, Bloohem. J., E,6P. (1986).

Sect. I V - Metabolic & E n d o c r i n e

178 -

Chapter 16.


Atherosclerosis

Joseph J . Ursprung, The Upjohn Company, Kalamazoo, Mich. Introduction. - Atherosclerosis appears t o be a "disease of regulation" (I. H. Page) i n which a g e n e t i c a l l y conditioned cardiovascular system i s rea c t i n g t o an ever-changing environment. The a b i l i t y t o regulate t h i s i n t e r a c t i o n determines i n t h e long run whether a t h e r o s c l e r o s i s w i l l , or w i l l not, p r e v a i l . The disease is a l e s i o n of l a r g e and medium-sized a r t e r i e s charact e r i z e d by i n t i m a l thickening with f o c a l deposits i n t h e intima of yellowish plaques containing l i p i d s , carbohydrates, blood products, fibrous material and calcium. I n t h i s c o n s t r i c t e d a r t e r y thrombus formation occurs i n t h e ulcerated atheromatous plaque which re,sults ultimately i n occlusion. Serum c h o l e s t e r o l l e v e l s and blood pressure a r e useful p r e d i c t o r s of t h e disease and obesity, smoking, l e v e l of physical a c t i v i t y , psycho-social influences, increased t r i g l y c e r i d e and carbohydrate metabolism, enhanced blood c l o t t i n g , hormonal balance and genetics a r e f a c t o r s which play a r o l e but t h e i r r o l e i s as yet unclear. There has evolved t h e concept t h a t a t h e r o s c l e r o s i s i s a multifaceted disease and t h a t no single cause e x i s t s . Two main theories, both of which a r e susceptible t o experimental investigation, e x i s t today. The f i l t r a t i o n concept of Aschoffl focused a t t e n t i o n on disordered l i p i d metabolism and s t i l l c o n s t i t u t e s the broadest approach t o atherogenesis while t h e thrombogenic theory proposed by Rokitansky (1844) and revived by M i d 2 l e d t o increasing i n t e r e s t i n intramural c l o t t i n g mechanisms and t h e i r r e l a t i o n s h i p with plasma l i p i d s . While l i p i d s appear t o bear a r e l a t i o n s h i p t o human a t h e r o s c l e r o s i s and associated thrombosis, t h e i r involvement s t i l l i s based on assumption r a t h e r than f a c t . Whether l i p i d s deposited i n t h e vessel come from t h e blood or a r e synthesized i n t h e blood v e s s e l i s s t i l l debated. Increasing a t t e n t i o n i s being paid t h e blood vessel, i t s e l f . I n t h e atherosclerosissusceptible White Carneau pigeon enhanced a o r t i c f a t t y a c i d and cholesterol e s t e r synthesis i s highly c o r r e l a t e d with t h e s e v e r i t y of t h e disease3. I n t h e rat, hypertension increases c h o l e s t e r o l synthesis4 and c h o l e s t e r o l levels5 i n t h e a o r t a as w e l l as i n t h e l i v e r and o t h e r tissues.' Chapman7 provides evidence t h a t t h e f o r c e which d i s r u p t s an a t h e r o s c l e r o t i c plaque t o form a thrombus proceeds from within t h e v e s s e l w a l l toward t h e lumen. Regardless, by far t h e g r e a t e s t e f f o r t has been concentrated on reducing blood liDid l e v e l s , p a r t i c u l a r l y c h o l e s t e r o l , i n t h e hy-perlipemic p a t i e n t . Diet. - Epidemiological s t u d i e s provide a basis f o r t h e hope t h a t d i e t a r y adjustment may reduce t h e incidence o r a t l e a s t delay the development of atheros c l e r o s i s and coronary h e a r t disease. Preliminary r e s u l t s from t h e national d i e t - h e a r t study8 and t h e "anti-coronary club'ls a r e encouraging and t h e A.M.A. Council on Foods and N u t r i t i o n recommends d i e t a r y treatmental and prophylaxis against coronary heart disease. The r i s k of coronary h e a r t disease seems t o bear a t l e a s t some r e l a t i o n s h i p t o c h o l e s t e r o l i n t h e blood as shown by t h e Framingham s t u d y . l o Among d i e t a r y agents which influence cholesteremia a r e t o t a l fats ,11 polyunsaturated fats ,I2 t h e r a t i o of polyunsaturated t o s a t u r a t e d fat,13 c h o l e ~ t e r o l ,amino ~ ~ a c i d content15 and carbohydrate .I6 A recent review17 discusses t h e r e l a t i o n s h i p of d i e t a r y f a t and coronary heart disease.

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Chap. 16

Atherosclerosis

Ursprung

179 -

A technique using t h e isotopic steady state24a suggests a limited cholest e r o l absorption i n man and t h i s may be h i s major protection against a high cholesterol diet24 since t h e r e appears t o be no feed-back mechanism i n man t o compensate f o r d i e t a r y c h o l e s t e r o l intake.24b On a high c h o l e s t e r o l d i e t 6080s of t h e serum c h o l e s t e r o l i s derived from endogenous sources.24a This contrasts with a recent report t h a t t h e serum l e v e l of c h o l e s t e r o l i n humans i s proportional t o t h e square root of t h e d i e t a r y intake of cholesterol.25 The r a t e of synthesis of c h o l e s t e r o l i n t h e s m a l l i n t e s t i n e a l s o i s independent of c h o l e s t e r o l feeding o r fasting.26 E a r l i e r work with primates showed that they do not respond t o d i e t a r y cholesterol; however, a t h e r o s c l e r o s i s can be induced27 when s a t u r a t e d f a t s a r e added t o a high c h o l e s t e r o l d i e t t o fac i l i t a t e absorption. Although c h o l e s t e r o l feeding w i l l produce myocardial inf a r c t s i n r a b b i t s , no c o r r e l a t i o n has been seen i n t h i s species between t h e occurrence of i n f a r c t s and t h e l e v e l of c h o l e s t e r o l i n t h e blood.23 The f a l l of serum c h o l e s t e r o l on feeding a d i e t high i n unsaturated f a t s occurs i n t h e absence of c h o l e s t e r o l excretion changes. This f a l l i n cholest e r o l l e v e l s i n t h e rabbit28 and i n man2’ seems t o be due t o plasma-tissue r e d i s t r i b u t i o n . An a l t e r a t i o n i n l i p o p r o t e i n s t r u c t u r e r e s u l t s such t h a t equilibrium between plasma and t i s s u e c h o l e s t e r o l pools favors t h e l a t t e r . 3 0 This c o r r e l a t e s with t h e finding that manipulating t h e d i e t a r y f a t intake i s not accompanied by a reciprocal change i n cholic acid turnover31 nor i s t h e r e a consistent r e l a t i o n s h i p between s t e r o l excretion and changes i n serum cholest e r o l concentrations. 32 The hypocholesteremic e f f e c t of d i e t a r y l i n o l e i c a c i d i n t h e r a b b i t appears t o be proportional t o t h e extent t o which l i n o l e i c a c i d i s incorporated i n t o plasma c h o l e s t e r o l e s t e r s . 34 Measurement of t h e l i p i d composition of a r t e r i a l t i s s u e and atheroma i n humans, however, has shown only an increased l i n o l e i c a c i d content i n atheroma i n those on a d i e t high i n uns a t u r a t e d fats as compared t o controls .33 A serum p r o t e i n deficiency i s reported i n humans with coronary a r t e r y An adequate intake of d i e t a r y p r o t e i n seems t o be necessary f o r disease.” e f f e c t i v e regression of coronary a t h e r o s c l e r o s i s i n chickend’In chickens on an atherogenic d i e t , cerebrosides and soy s t e r o l s reduce serum c h o l e s t e r o l and t h i s reduction c o r r e l a t e s with retarded development of a t h e r o s c l e r o s i s .20 It has a l s o been suggested t h a t a substance i n soy bean meal w i l l p r o t e c t rabb i t s on a high f a t d i e t against a t h e r o s c l e r o s i s .22 Serum Lipids. - Many attempts have been made t o reduce serum c h o l e s t e r o l by i n h i b i t i n g i t s biosynthesis. Triparanol w a s introduced some years ago f o r t h i s purpose but w a s withdrawn because of severe systemic reactionsa7 ( l e n t i c u l a r c a t a r a c t s , alopecia and i c h t h y o s i s ) . It a l s o appears t o increase a o r t i c a t h e r o s c l e r o s i s i n chickens38 and produces congenital malformations i n mice and rats.3s Compounds recently reported, which a r e s i m i l a r i n many respects t o t r i p a r a n o l , include some pyridyl analogs,40 c y a n ~ s t i l b e n e s ,triarylmeth~~ anols42 and other b a s i c ~ a r b i n o l s . ~ ~ Of some b a s i c e t h e r s of N-hetero-substituted a n i l i n e s which show cholest e r o l lowering a c t i v i t y , 4 3 compound 1 i s most a c t i v e . Three new c l a s s e s of

1.

2.

180

Sect. IV

H

-



6 3 0 4.

3.

inhibitors are shown in structures 2 [journal gives name as 4-(2-chlorophenyl)a-(p-methoxyphenoxymethyl) -1-piperazine] , 3 and 4.44 These compounds (2-4)were shown to accumulate ~-dehydrocholesterolin the plasma and tissues of rats and in this respect are similar to compounds related to AY-9944 reported by Ayerst.45 25-Azacholesterol blocks cholesterol synthesis at the desmosterol stage4" as has also been seen with 20,25-dia~a-~~ and 22,25-diazacholesterol.48 In man 20,25diazacholesterol lowers blood cholesterol but toxic effects are numerous 47b Myatonia and Keratoderma have been rep0rted4~and in each instance serum desmosterol was elevated and cholesterol was reduced at the time these toxic effects became evident. Some 4-azachole~tenes~~ have also been reported to inhibit cholesterol synthesis. Cyclization of squalene is inhibited by t0lbutamide5~while phenethylbiguanide inhibits conversion of farnesyl pyrophosphate to squalene 51 Phenyl- and biphenyl-substituted acids have been studied extensively f o r their cholesterol lowering activity.52 Activity is reported also with biphenyl ether-substituted acids.s2c The agent of most interest in this area remains pThe reader is chlorophenoxyisobutyric acid (CPIB, Clofibrate, atromid S) directed to the Atromid for background information. In bovine vascular tissue in vitr054, in rats55 and in man56 CPIB inhibits cholesterol biosynthesis, apparently between mevalonic acid and isopentenyl pyrophosphate 55 It was again confirmed that CPIB alone is as active as the combination of CPIB and androsterone (Atromid)57 and that it lowers triglycerides to a greater extent than cholester01.57b It also markedly decreases low density lipoprotein (a suggested mode of action f o r CPIB)S8 and reduces the glyceride content of high density lipoprotein. CPIB is reported to decrease the B/ol lipoprotein ratios9 and increase uric acid excretion.60 The norepinephrine-induced rise in free fatty acid levels is unaffected by CPIB in humans."l The effect of CPIB on the fibrinolytic system is variable62 but does not appear to be significant.63 Prospective studies of large groups has verified that the risk of myocardial infarctions is substantially greater in cigarette smokers than in non-smokers64 and this appears to be mediated via the nicotine-induced release of e~inephrine.~~ Nicotine, in dogs, has been shown to raise cholestero166 and blood sugar67 and this may be related to the elevation of free fatty acid levels?" Caffeine raises free fatty acid levels68 and it is suggested that coffee intake can be associated with heart disease.64b Agents which will regulate free fatty acid levels are of interest both in diabetes and atherosclerosis. 3,5-Mmethyli~oxazole,~~ 3,5-dirnethylpyra~ole~~ and its metabolite, 5-methylpyrazole-3-carboxylic acid7' dramatically lower fatty acids and blood sugar in animals. Infusion of norepinephrine produces a rapid rise in free fatty acid and in plasma triglycerides of l o w density lipoprotein.72 Nicotinic acid blocks this norepinephrine-induced rise in free fatty acid73r"l and lowers free fatty acid74 and triglyceride75 levels in the blood. It is also reported to reduce the cholesterol content of various tissues in cholesterol-fed

.

.

.

Chap. 16

Atherosclerosis

U r sp rung

181 -

~ l~u m i r a b b i t s .76 I n humans it produces abnormal carbohydrate m e t a b o l i ~ m . A num n i c o t i n a t e i s e f f e c t i v e as a hypocholesteremic agent and appears t o be b e t t e r t o l e r a t e d than n i c o t i n i c acid.78 A s e r i e s of methoxamine analogs7’ and a v a r i e t y of antidepressants80 a r e a l s o reported t o block t h e l i p o l y t i c e f f e c t s of epinephrine. Single i n j e c t i o n s of i n s u l i n cause acute f a l l s i n f r e e f a t t y acids i n man82 while i n another study a combination of potassium, glucose and i n s u l i n has been used t o t r e a t myocardial i n f a r c t i o n with some b e n e f i t .el Various agents reported t o lower c h o l e s t e r o l i n animals a r e chondroitin s u l f a t e A,83 vanadium,84 a mitochondria1 f r a c t i o n from starved rat liver8’ and i n man, 6-azauridine,eSa p-aminosalicylic acide6 and a r e l a t i v e of heparin, a s u l f a t e d polyanion SP54.e7 I n s u l i n i s reported t o decrease t h e c h o l e s t e r o l content of blood and a o r t a while increasing t h e l e v e l i n l i v e r and adrenalse7& i n cholesterol-fed r a b b i t s . I n p r i n c i p l e , feeding substances which remove b i l e acids from t h e i n t e s t i n e and which prevent t h e i r reabsorption should increase b i l e acid excretion and speed up c h o l e s t e r o l degradation. This i s , indeed, possible with agents such as f e r r i c chloride,88 aluminum hydroxide89 and with d i e t a r y saponins. so The b i l e acid-binding anion-exchange r e s i n MK-135 (Cholestyramine)s1 shows marked lowering of serum c h o l e s t e r o l i n t h e chicken, rabbit,s2 dogs3 and mans4 and has u t i l i t y i n r e l i e v i n g p r u r i t i s associated with b i l i a r y c i r r h o s i s .95 Steatorrhea i s a problem with t h i s drug97 but a r e p o r t i n d i c a t e s that when medium chain t r i g l y c e r i d e s a r e s u b s t i t u t e d f o r t h e long chain t r i g l y c e r i d e s i n t h e d i e t t h i s i s controlled.s8 Metamucil, an o r a l hydrophilic c o l l o i d , i s also reported t o lower serum cholesterol.S9 P-SitosterolLo0 plays a r o l e i n i n h i b i t i n g absorption of c h o l e s t e r o l . The a n t i b i o t i c s neomycin, N-methylated neomycin, but not streptomycin or Nacetylated neomycin, reduce c h o l e s t e r o l i n t h e chick,lol presumably by i n t e r f e r i n g with absorption processes. Paramomycin a l s o lowers serum c h o l e s t e r o l while reducing b a c t e r i a l f l o r a . l o 2 The r o l e of hyperglyceridemia i n a t h e r o s c l e r o s i s i s s t i l l cloudylo3 but it appears that t h e t r i g l y c e r i d e l e v e l i s no more u s e f u l than c h o l e s t e r o l l e v e l s i n i d e n t i f y i n g subjects with ischemic h e a r t disease .Io4 P a t i e n t s with elevated t r i g l y c e r i d e s a l s o have a high incidence of elevated f a s t i n g blood sugars and elevated f r e e f a t t y a c i d s l o s and thus have an increased r i s k of myocardial i n f a r c t i o n and l a t e n t diabetes. It i s perhaps s i g n i f i c a n t that i n t h e rat u t i l i z a t i o n of fat for energy a c c e l e r a t e s c h o l e s t e r o l b i o ~ y n t h e s i s . ~ 5 The development of some v a r i e t i e s of hy-pertriglyceridemia i s accompanied by a corresponding increase i n t h e turnover of palmitate but not l i n o l e a t e . This may represent increased synthesis of l i p i d from carbohydrate.106 I n s u l i n decreases t h e plasma l e v e l s of glyceride i n p a t i e n t s with hy-pertriglyceridemia?08 Protamine s u l f a t e , an i n h i b i t o r of l i p o p r o t e i n l i p a s e , i n h i b i t s t h i s a c t i o n . CPIB appears t o be t h e b e s t agent t o date f o r lowering elevated t r i g l y c e r i d e l e v e l s . 5713 Hormones. - I n t e r e s t i n estrogens stems from reports t h a t coronary a r t e r y disease i s a r a r i t y among premenopausal women1o9 and t h a t it i s much g r e a t e r i n c a s t r a t e d women than i n those having undergone hysterectomy but retain t h e i r ovaries,losb although t h i s finding i s not without i t s c r i t i c s . 1 1 0 On t h e o t h e r side, c a s t r a t e d men a r e less prone t o develop coronary disease than normal menyll Estrogens i n humans increase a-lipoprotein ( r i c h i n phospholipid P) l e v e l s but t h e i r e f f e c t on f5-lipoproteins ( r i c h i n c h o l e s t e r o l C ) i s v a r i a b l e . Thus,

182 -

Sect. IV

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Metabolic 81 E n d o c r i n e


t h e C/P r a t i o w i l l decrease but t h e r e may o r may not be a drop i n c h o l e s t e r o l l e v e l s . l 1 2 Lecithin appears t o be t h e only major phospholipid f r a c t i o n which i s increased.113 Triglyceride l e v e l s a r e a l s o increased by estrogen administ r a t i o n . l l 4 Estrogens p r o t e c t t h e coronary a r t e r i e s but not t h e a o r t a of t h e chicken.l15 Experiments i n rats had l i k e e f f e c t s but r a b b i t s f a i l e d t o show b e n e f i t from estrogens.l16 Efficacy i n humans s t i l l remains a will-of-thewisp. S i g n i f i c a n t evidence of t h e i r prophylactic value against myocardial i n f a r c t i o n has not as y e t been demonstrated.117 Mental functioning i n p a t i e n t s with cardiovascular and cerebrovascular disease i s reported t o improve with estrogen treatment Since t h e s i d e e f f e c t s of estrogen i n t h e male a r e a problem, much e f f o r t has been devoted t o t h e search f o r compounds having t h e l i p i d p r o f i l e of an estrogen but devoid of i t s feminizing properties.l18 Among recent compounds studied a r e a s e r i e s of 1-methyl l3-alkyl estrogens120 and a s e r i e s of 3-alkyloxy-l7,17-(or 16,16)ethylenedioxy e s t r a t r i e n e s . 1 2 l Compounds 5"' and 6123 a r e reported t o show a possible s p l i t between t h e i r feminizing and l i p i d p r o p e r t i e s . On t h e p o s s i b i l i t y t h a t a metabolite i s responsible f o r

B

C-W2

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t h e l i p i d e f f e c t s of estrogens, a s e r i e s of 2-hydroxy- and 2-methoxy-estradiols and t h e i r 16-oxygenated analogs w a s investigated. Com ound 7 i s reported t o have a l a r g e s p l i t between t h e properties i n question. p24 Conjugated equine estrogens increase blood p l a t e l e t levels125 during lipemia following i t s administration but o r a l contraceptives have l i t t l e e f f e c t , i f any, on blood coagulation o r f i b r i n o l y s i s l Z 6 (including p l a t e l e t adhesiveness) except perhaps t o increase f a c t o r V I I l e v e l s .Iz7 Estrogen therapy increases plasma hydrocortisone apparently by increasing t r a n s c o r t i n l e v e l s . 12' Gonadoptropins increase side-chain cleavage of c h o l e s t e r o l but not 20a -hydroxy cholesterol inThis i s i n d i c a t i n g t h a t 20a -hydroxylation i s stimulated by gonadotropins l i n e with t h e recent report that estrogen may decrease c h o l e s t e r o l by increasing t h e turnover r a t e , and therefore, t h e catabolism of c h 0 1 e s t e r o l . l ~ ~The f a c t that it i s not a c t i v e o r a l l y stimulated some e f f o r t i n t o finding an androsterone analog which i s a c t i v e o r a l l y . 3a-Methoxy-17-methyl-5a -androstan-l7@-ol i s reported t o lower c h o l e s t e r o l levels134 and enhance excretion of cholesterol i n t h e b i l e of rats.135 Methalone, an anabolic s t e r o i d , a l s o decreases t h e l e v e l of c h o l e s t e r o l i n man.'" Cortisone increases l e v e l s of triglyceri.de, phospholipid and c h o l e s t e r o l i n rats but does not a l t e r i n t e s t i n a l absorption o r t h e r a t e of incorporation of a c e t a t e i n t o cholesterol.137 I n c h o l e s t e r o l fed r a b b i t s adrenal hypertrophy precedes deposition of c h o l e s t e r o l and it i s suggested t h a t t h e adrenal gland

Chap. 16

Atherosclerosis

U r sp r ung

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may a c t as a regulator intervening i n t h e process r e s p o i s i k l e f o r atheros ~ 1 e r o s i s . l I~n~man, hyperlipemia has been seen i n acute ad-renocortical insufficiency and successfully t r e a t e d with hydrocortisone .13' The use of adrenocorticotropic g e l has given encouraging r e s u l t s i n some cases of acute myocardial infarction.14' The hypothyroid s t a t e i s associated with an elevated plasma c h o l e s t e r o l l e v e l while t h e hyperthyroid s t a t e i s associated with low c h o l e s t e r o l l e v e l s i n plasma.141 It w a s again pointed out that i n a l a r g e number of p a t i e n t s hospitalized with acute myocardial i n f a r c t i o n t h e serum PBI l e v e l s a r e lower than The effectiveness of thyroactive substances i n lowering serum c h o l e s t e r o l and i n reducing atherogenesis has been amply demonstrated i n various animal species14' but t h e i r c l i n i c a l use remains r e s t r i c t e d because of t h e i r a c t i o n on b a s a l metabolic r a t e , and i n p a r t i c u l a r , on oxygen consumpt i o n of t h e myocardium and aggravation of angina. 14' Therefore , i n t e r e s t i s focussed on drugs whose e f f e c t on l i p i d metabolism i s accentuated r e l a t i v e t o t h e i r hypermetabolic e f f e c t . Many thyroxine analogs have been made, some of which a r e reported t o have a d e s i r a b l e " s p l i t " i n t h e two a c t i v i t i e s . 1 4 4 A comprehensive review of t h i s sub Sect has been published r e ~ e n t 1 y . l ~ ~ The thyroxine analogs of most i n t e r e s t a t t h e present time a r e D t h y roxine ( D T , ) and Dtriiodothyronine ( D T 3 ) . A controversy s t i l l e x i s t s as t o whether t h e r e i s any separation of l i p i d and calorigenic e f f e c t s of these two agents as compared t o t h ~ r 0 x i n e . l D ~T ~ 3 i s claimed t o lower serum l i p i d s i n p a t i e n t s with e s s e n t i a l hy-perlipemia but showed no e f f e c t i n nomolipemic controls.'47 As with D T 4 it a l s o appears t o show a worsening of angina o r arrhythmia i n humans. 14' Some more recent thyroxine-like compounds which have been studied extensively include Dtrichlorothyronine,149 4'-methoxy-3 ,3'-5triiodothyroacetic acid150 and a s e r i e s of t h y r ~ a l k a n o l s which l ~ ~ a l s o appeared t o show a " s p l i t " i n animals. !l?hyroidectomy i n rats has no e f f e c t on oxidation of e i t h e r labeled cholest e r o l o r sodium octanoate. Preliminary nuclear changes i n c h o l e s t e r o l take place a t about t h e same r a t e regardless of t h e thyroid s t a t e . This and o t h e r data a r e consistent with the e a r l i e r hypothesis t h a t t h e e f f e c t of t h e thyroid on cholesterol metabolism may be mediated a t t h e l e v e l of nuclear hydroxylation of t h e ~ t e r 0 i d . l ~ ' Increased thyroid l e v e l s decreases t h e production of e s t r i o l from e s t r a d i o l and increases production of 2-methoxyestrone. A recent shows t h a t 2-hydroxyestrone becomes t h e major metabolite i n subjects with high thyroid l e v e l s and t h a t i n myxedema 2-hydroxyestrone l e v e l s a r e diminished. The production of androsterone diminishes i n hypothyroidism and it has been postulated that t h i s produces increased l i p i d l e v e l s .132 These complicated endocrine i n t e r a c t i o n s make a study of thyroid a c t i v i t y d i f f i c u l t and i t s e f f e c t on l i p i d metabolism remains t o be c l a r i f i e d . Thrombosis and F i b r i n o l y s i s . - I n t e r e s t i n t h e thrombogenic theory of a t h e r o s c l e r o s i s proposed by von Rokitansky and revived by t h e s t u d i e s of D u g u i e has an experimental basis. A r t i f i c i a l production of f i b r i n deposits o r thrombi on vessels w i l l give rise t o intimal thickening and eventually a t h e r o s c l e r o s i s .156 Fibrin-like material has been demonstrated i n a t h e r o s c l e r o t i c l e s i o n s . lS7 locali z a t i o n of atheromatus changes may be r e l a t e d t o mechanical forces which lead t o t h e formation of thrombi a t s t r e s s points.15' The influence o f l i p i d s i n t h e pathogenesis of a t h e r o s c l e r o s i s might be f e l t not only i n t h e i r deposition i n t h e intimal l e s i o n but a l s o i n t h e i r clot-promoting effectsL5' (phospholipids

184

Sect. I V

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Metabolic & E n d o c r i n e


and f r e e f a t t y acids can produce p l a t e l e t aggregation16') and t h e i r capacity t o i n h i b i t f i b r i n o l y s i s . 161,1ssb Chemical a t t a c k i n t h i s area has been a t i n h i b i t i n g t h e i n i t i a l event, p l a t e l e t aggregation, and a t d i s s o l u t i o n of t h e thrombus ( f i b r i n o l y s i s ) . For background t h e reader i s d i r e c t e d t o a comprehensive review on p l a t e l e t s and atherosclerosisl6* and t h e recent workshop on f i b r i n o l y s i s 163 Adenosine diphosphate (ADP) w i l l aggregate p l a t e l e t s i n v i t r o and t h i s aggregation can be prevented by enzymatic conversion of t h e ADP t o ATP.le4 This induced aggregation requires a complexable c a t i o n and fibrinogen. 16' The formation of thrombin and ADP a few seconds a f t e r blood i s shed has been demonstrated i n vivolB6 and thus both of these agents a r e present before t h e p l a t e l e t s a r e a v a i l a b l e . Epinephrine a l s o induces p l a t e l e t aggregation'" and thrombosis i n rats167 along with norepinephrine and serotonin. Pronethalol, a @-blocker, blocks t h e epinephrine-induced p l a t e l e t rise and @-Blocking agents have a l s o been found u s e f u l i n a l e v i a t i n g angina of effort1" and propranalol i s reported t o reduce t h e mortality from acute myocardial infar~ti0n.l~' I n i t i a l reports17' t h a t l i n o l e n i c acid caused a decrease i n p l a t e l e t adhesiveness and reduced t h e incidence of experimental thrombosis have been controverted by t h e same and by others.173 Among materials which are reported t o reduce p l a t e l e t adhesiveness a r e M p y r a m i d ~ l e ,a~s~e ~ r i e s of adenosine analogs,175 histamine17' and methyl mercuric nitrate.177 M.A.O. i n h i b i t o r s were shown not t o p r o t e c t against experimental thrombosis,178 i n disagreement with an e a r l i e r report. Dextran appears t o have some c l i n i c a l u t i l i t y i n thrombus inhibition17' and has been successfully used i n severe ischemia."' It appears t o i n h i b i t p l a t e l e t f a c t o r I11 by coating t h e platelet The r o l e of anticoagulants i n the treatment of myocardial i n f a r c t i o n i s unclear. Experiments with rabbits,lE3 dogs184 and rats185 have shown t h a t heparin w i l l prevent experimentally induced thrombosis. Conflicting reports suggest that anticoagulants may prolong t h e time f o r p l a t e l e t aggregation186 but heparin i n man showed no consistent changes i n p l a t e l e t economy or platel e t adhesiveness187 and only a feeble e f f e c t i n protecting against thrombotic occlusion a f t e r a r t e r i a l reconstruction.18' Increased s e n s i t i v i t y t o heparin w a s seen i n p a t i e n t s following acute myocardial infarction."' I n patients who suffered a myocardial i n f a r c t i o n while on anticoagulant therapy, t h e r e was a decrease i n anticoagulant l e v e l s as compared t o those with no myocardial infarction.'" I n p a t i e n t s with coronary heart disease t h e hematocrit and whole blood v i s c o s i t y is s i g n i f i c a n t l y higher than i n normals."' The r o l e played by t h e l i p i d - c l e a r i n g a c t i v i t y of heparin is s t i l l under i n v e s t i g a t i o d S 2 Long term anticoagulant therapy a f t e r myocardial infarction, using heparin"' and t h e c o u m a r i n ~appears ~ ~ ~ t o be b e n e f i c i a l and it has been recommendedlS5 t h a t t h i s form of treatment be used routinely. I n a cephalin f r a c t i o n which stimulated t h e c l o t t i n g mechanism, it w a s found that phosphatidyl-ethanolamine w a s t h e only component which showed cons i s t e n t high activity."' I n a study of p a t i e n t s with myocardial i n f a r c t i o n these authors1'' showed t h a t , although t h e t o t a l cephalin f r a c t i o n was similar t o t h a t i n t h e controls, t h e p a t i e n t s had cephalin with higher c l o t t i n g a c t i v i t y and markedly higher o l e i c a c i d content. I n s u l i n produces a c c e l e r a t i o n of blood c l o t t i n g and decreases f i b r i n o l y t i c a c t i v i t y l S 8 i n dogs, a t t r i b u t e d t o t h e sympathico-adrenal mechanisms for r e s t o r a t i o n of normal glycemia since it i s

.

Chap. 16

Atherosclerosis

Ur sprung

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blocked by dihydroergotamine. P r o g e s t a t i o n a l agents a r e a l s o reported t o produce hypercoagulability i n w ~ m e n . ~ ” Thrombolyt i c therapy has r e c e n t l y been reviewed. 2oo The enzymes s t r e p t o ~ ~ ~appear , t o have u t i l i t y i n kinase, 201 staphylokinase202 and u r o k i n a ~ e201c acute thromboembolic v a s c u l a r d i s e a s e s . CA-7 (a f i b r i n o l y t i c enzyme from a s p e r g i l l u s oryzae) has produced l y s i s of arterial thrombi i n dogs 9204 Phenformin205 (DBI) and Metformin206 have shown promise as f i b r i n o l y t i c agents which may be u s e f u l i n t h e prophylaxis of a r t e r i a l occlusion. The authors have suggested t h a t phenformin a c t s l i k e a c o r t i c o i d and have indeed shown i t t o be b e n e f i c i a l i n rheumatoid a r t h r i t i s . 2 c ” An e a r l i e r report207 t h a t atromid has f i b r i n o l y t i c a c t i v i t y w a s c o n t r a d i c t e d recently.208 A l a r g e number of vasoactive drugs, both hyper- and hypotensive a r e reported t o have f i b r i n o l y t i c a c t i v i t y which i s r e l a t e d t o t h e i r vasoactive changes .209 Complamin (xanthinol n i c o t i n a t e ) has been shown t o possess f i b r i n o l y t i c a c t i v i t y i n but t h e p a t i e n t s very quickly develop a t o l e r a n c e t o t h e drug. Psycho-Social Factors. - One group of investigators211 has undertaken t h e study of behavior p a t t e r n s and t h e i r r e l a t i o n s h i p t o coronary artery d i s e a s e . They f i n d t h a t “Behavior P a t t e r n A” ( r e s t l e s s , competitive a t t i t u d e ) men have higher c h o l e s t e r o l levels,212 faster c l o t t i n g times212 and have a much higher incidence of arcus s e n i l i s and coronary artery d i s e a s e O 2 l 3 The same r e l a t i o n s h i p w a s found i n women.214 I n d i v i d u a l s harboring p a t t e r n A e x c r e t e more epinephrine during t h e i r working day t h a n t h o s e i n p a t t e r n B ( r e l a t i v e l y nonambitious, non-aggressive) .215 Subjects of p a t t e r n A have a l s o shown a high incidence of blood sludging a fte r a f a t t y m s a l whether t h e fats were s a t u r a t e d o r unsaturated, while sludging w a s v i r t u a l l y absent i n non-coronary prone ind i v i d u a l s .218 S i m i l a r r e l a t i o n s h i p s occur when animals a r e stressed.216 It i s implied t h a t s o c i a l f a c t o r s may account f o r t h e low incidence of myocardial i n f a r c t i o n i n Roseto, Pa.217 The i n h a b i t a n t s a r e s t r i k i n g l y obese, eat cons i d e r a b l e q u a n t i t i e s of animal f a t and t h e i r serum l i p i d p a t t e r n s do not d i f f e r from those found i n t h e Framingham study,loa y e t t h e y have a very low incidence of myocardial i n f a r c t s as compared t o t h o s e i n t h e Framingham study. Summary. - There i s c l e a r l y no u n i f i e d concept of atherogenesis. Knowledge i n t h e f i e l d i s c h a o t i c and treatment, o r prevention, i s s t i l l a matter of opinion. The p r e f e r r e d method f o r i n h i b i t i n g atherogenesis i s s t i l l c o n t r o l of t h e d i e t . O f i n t e r e s t i s t h e evidence which shows t h a t s u b s t i t u t i n g unsatur a t e d f o r s a t u r a t e d fats i n t h e d i e t causes a plasma-tissue r e d i s t r i b u t i o n r a t h e r t h a n i n h i b i t i n g s y n t h e s i s o r i n c r e a s i n g e x c r e t i o n r a t e s of c h o l e s t e r o l . Dietary c h o l e s t e r o l seems t o play only a minor r o l e , i f any, i n t h e development of human a t h e r o s c l e r o s i s . Drugs which lower serum l i p i d s are s t i l l s c a r c e . Efficacy of CPIB on long term treatment of t h e disease remains t o be seen. Cholestyramine, D T 4 , estrogens and n i c o t i n i c a c i d have t h e i r champions and w i l l f i n d s p e c i a l usage. Increased a c t i v i t y has focusSed a t t e n t i o n on p l a t e l e t adhesiveness, although no promising agent has emerged as y e t . The f i b r i n o l y t i c enzymes s t i l l are t h e b e s t agents f o r f i b r i n o l y s i s therapy. A s t a r t has been made i n unraveling psycho-social f a c t o r s and r e l a t i n g behavior w i t h serum l i p i d p a t t e r n s and proneness t o coronary h e a r t d i s e a s e . Research i n a t h e r o s c l e r o s i s must s t i l l be considered i n i t s infancy. With i n c r e a s i n g i n t e r e s t by medical s c i e n t i s t s and by governmental agencies, progress a t an a c c e l e r a t e d rate can be expected.

Sect. IV

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R e f e renc e s 1.

2. 3. 4.

56.

L. Aschoff, V o r t r l g e fiber P a t h o l o g i e , F i s c h e r , J e n a , Germany, 1925, pp. 62-84. J . B. Duguid, J . P a t h o l . B a c t e r i o l . , 507 (1946). H. B. L o f f l a n d and T. B. Clarkson, Arch. P a t h . , &, 2 9 1 (1965). M. M. Daly, Q. B. Deming, V. M. Raeff and L. M. Brun, J. C l i n . I n v e s t . , 1606 (1963). M. M. Daly and V. R a e f f , B u l l . N. Y. Acad. Med., G, 225 (19651. H. N. Adel, 9. B. Deming, M. M. Daly, V. M. Raeff and L. M. Brun, J . Lab. C l i n . Med.,

2,

2,

66.

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1075 (1965). J . W. C o n s t a n t i n e , Nature, 9 1 (1965). C. W. Robinson, J r . , S. C. Kreas, R. H. Wagner and K. M. Brinkhous, Exptl. Mol. P a t h o l . , 2, 457 (1965). 178 S. V. Chandra and S. H. Z a i d i , J. A t h e r o s c l e r o s i s R e s . , 5 , 249 (1965). 5cZ (1965). ( b ) W. M. 179 * ( a ) R. B. Sawyer and J. A. Moncrief, Arch. Surg., Chadduck, W. G. C r u t c h f i e l d and M. Roberts, S w g . Gynec. O b s t e t . , 121, 491 (1965). 180. J. J . Bergan, 0. H. T r i p p e l and A. H. Kaupp, Arch. S u r g . , 338 (1965). 182. R. A. Ewald, S. W. E i c h e l b e r g e r , Jr.. A. A. Young, H. J. Weiss and W. H. Crosby, T r a n s f u s i o n , 2, 109 (1965). 183. V. Ourewich and D. P. Thomas, J . Lab. C l i n . Med., 604 (1965). 184. R. D. Williams and F. K a r a f f a , Surg. Gynec. O b s t e t . , 309 (1965). 185. I. L u s t r i n Surgery, 857 (1965). 186. G. P. McNicol and A . S. Douglas, Lancet I , 729 (1965). 187. J. F. Mustard, F. B. G i l b e r t and E. A. Murphy, Lancet I , 575 (1965). 188. E. W . Salzman, Surgery, 131 (1965). 189. C. Dufaillt, Canad. Med. Assoc. J., 2,13 (1965). 190. K. Molne and P. F. H j o r t , Acta Med. Scand., 121, 571 (1965). 191. G. A. Mayer, Capad. Med. Assoc. J . , 1151 (1965). 192. P. T. Kuo, D. R . B a s s e t t and A. M. DiGeorge, C i r c . Res., &I 2 2 1 (1965). , J. A t h e r o s c l e r o s i s Res., 5, 253 (19653. 193 * L. E. B t l t t i g e r , L. A. Carlson 194. V. A. Cooperative Study, R. V. E b e r t . c h r . , J . Am. Med. Assoc., 929 (1965). 195. D. Leak, G e r i a t r i c s , 20, 150 (1965). 196. J . D. B i l l i m o r i a , V. J. 1 - a d and N. F. Maclagan, J . A t h e r o s c l e r o s i s R e s . , 2, 9 0 , 102 (19651 198. M. I . Mamikonyan, Byul. Eksp. B i o l . Med., 1049 (1965). 199 R. R. Margulis, J. L. h b r u s , L. B. Mink and J. C . S t r y k e r , Am. J. O b s t e t . Gynecol., 2, 161 (1965). 200. D. Jewson, Minnesota Med., 4&, 1363 (1965). 201. 856 (1965). ( b ) ( a ) D. Cavanagh and E. A. Albores, Am. J . O b s t e t . Gynecol., M. C . Rozenberg, A u s t r a l i a n J. E x p t l . B i o l . Med. S c i . , 245 (1965). ( c ) C . D. Jacobsen and A. B. Chandler., Scand. J. Clin. Lab. I n v e s t . , s u p p l . . 8 , 2 2 5 (1965). ( d ) J . E. Nilehu and B. Robertson, Scand. J. Haematol., 2, 267 (1925). ( e ) L. B. Fleming and E. E. C l i p t o n , J . Surg. Res., 5, 153 (1965). 202. B. Sweet, A. P. McNicol and A. S. Douglas, Clin. S c i . , 3,375 (1965). 203. A. P. F l e t c h e r &- &., J. Lab. Clin. Med., &, 713 (1965). 731 (1965). 204. W. H. E. Roschlau and A. L. Tosoni, Can. J. Physiol. P h a r n a c o l . , 205. G. R. F e a r n l e y . R. C h a k r a b a r t i and E. D. Hocking, Lancet I, 9 (1965). 206. R. C h a k r a b a r t i , E. D. Hocking and G. R. F e a r n l e y , Lancet 11, 256 (1965). 207. S. C. S r i v a s t a v a . M. J. Smith and H. A. Dewar, J. A t h e r o s c l e r o s i s R e s . , 1. 640 t1963). 208. B. Sweet, B. M. R i f k i n d , G . P. McNicol and M. Gale, J. A t h e r o s c l e r o s i s Res.. 3, 347

a,

176. 177. I

E,

s,

&.,

66, 121,

s,

x,

s,

&.

x,

s,

5,

z,

5,

(1965 1 *

Holemans, Am. J. P h y s i o l . , 208, 511 (1965). P. McNicol and A. S. Douglas, B r i t . Med. J . . I , 1149 (1965). Friedman, G e r i a t r i c s , 2, 562 (1964). Friedman, R. H. Rosenman and V. C a r r o l , C i r c u l a t i o n , 852 (1958). Friedman and R. H. Rosenman, J. Am. Med. Assoc., 1286 (19591.' H. Rosenman and M. Friedman, C i r c u l a t i o n , 4, 1173 (1961). Friedman, S. S t . George, S. 0. Eyers and R. H. Rosenman, J . Clin. I n v e s t . ,

209. 210. 211. 212. 213. 214. 215.

R. G. M. M. M. R. M.

216.

( a ) H. S o b e l , C . E. Mondon and R . S t r a u s , C i r c . R e s . , 11,971 ( 1 9 6 2 ) . ( b ) H. L. Ratcliffe, Circulation, 481 (1963). C. S t o u t , J. Morrow, E. N. Brandt, Jr. and S. Wolf, J . Am. Med. Assoc., 845 (1964). M. Friedman. S. 0. Byers and R. H. Friedman, J . Am. Med. Assoc., B, 882 (1965).

217. 218.

a,

a,

758 (19601.

a,

188,

2,

Chapter 17. , Non-steroidal Hormones and Their Antagonists Eugene C. Jorgensen, School of Pharmacy, University California, San Francisco, Calif. INTRODUCTION The non-steroidal hormones considered in this section are composed primarily of amino acid derivatives. Structures of the simpler substances, such as the thyroid hormones and oxytocin and vasopressin have been known for some time. Recent advances center around structural variations of known hormones, structural elucidation of new hormones, and efforts of the initial syntheses of hormones whose structures have been proposed on the basis of degradation studies. The compounds selected for review are limited to those whose structures are known, or have been proposed, and in which significant recent progress has been made in the synthesis of the hormone or of its analogs. A hormone is generally considered to be a discrete chemical substance, produced in a gland, secreted into the body fluids, and producing a specific effect on the activities of other organs. The "glandular hormones" clearly belong to this class. Recently, a number of peptides with intense pharmacological activities have been found to be generated by specific enzyme catalyzed hydrolysis of plasma proteins; these have been called "tissue hormones.'' An additional miscellaneous group related by peptide nature and pharmacological properties have thus far been isolated only from non-mammalian sources.

HORMONES OF THE PANCREAS .Insulin.--Recombination experiments of synthetic and natural A and B chains of insulin have been reported from German, Chinese and American groups. The Aachen group described a synthesis of the A-chain of sheep insulin and its combination with the native B-chain to produce biological and chemical properties like those of insu1in.l Synthesis of the B-chain and condensation with the native sheep A-chain produced about 0.655; insulin activity.2 Combination of synthetic A and B chains of sheep insulin produced biological activity 0.2 to 1.0% that of native insulin.3 An improved recombination of bovine insulin was reported to produce 44% insulin-like activit using a 1:l mixture of the preoxidized A-chain and the reduced B-chain.

tr

The Shanghai-Peking groups reported combinations of synthetic B-chain with the natural A-chain of bovine insulin, and of the synthetic A-chain with the natural B-chain to give crystalline products with 2-4% of the activity of natural insulin: 5 , 6 slight biological activity was obtained initially by combining synthetic A and B chains. Improved synthesis of A and B chains,' using azide condensations at the final stages of synthesis to preclude racemization, and use of excess of the A-chain and air oxidation at pH 10.68 led to a synthetic bovine insulin with initial activity of 1.2-2.5% that of natural insulin based on the protein concentration present. Purification by solvent extraction and crystallization in a citrate buffer containing acetone and zinc acetate yielded a crystalline product identical in crystal shape and biological activity (mouse convulsion and rabbit hypoglycemia) with natural bovine insulin. Chromatographic and isotope dilution studies with C-14 labeled synthetic insulin

192 -

Sect. IV - Metabolic & Endocrine


confirmed identity with the natural protein. The Pittsburgh group has followed earlier work on the combination of s p thetic A-chain and natural B-chain of sheep insulin (0.5-1.2% activity) ,l o with synthesis of the B-chain and combination of this with the natural Achain to produce insulin-like activity equivalent to that produced by recombination of the natural A and B chains.ll Considerable activity was also found when synthetic B-chain was combined with a partially purified preparation of synthetic A-chain. The B-chain of human insulin has been prepared as the S-sulfonate and combined with the natural A-chain of bovine insulin to produce 4-8% the activity of crystalline bovine insulin.12 Synthesis of human A-chain, and combination with synthetic human B-chain and with natural bovine B-chain yielded 2% and 8% insulin activity by the mouse convulsion method.13 The combined results of the German, Chinese and American groups indicate that totally synthetic preparation of pure human insulin is possible with presently available techniques, and that the tools are available for important studies of insulin analogs. Glucagon.--The amino acid sequence of the glycogenolytic pancreatic hormone, glucagon, was determined by Bromer and co-workers in 1957. Partial syntheses of the linear peptide, which contains 29 amino acids, have been reported by Schr6der14, and by Wtinschl5 , but biological activities have not yet been reported for these glucagon-related peptides, and the complete synthesis of glucagon is not yet reported. HORMONES OF THE PITUITARY The Melanocyatimulating Hormones (M2-5) and Adrenocorticotropic Hormones JACTH).--Presence of the same amino acid sequence from 4 through 10 may account for certain common biological properties of MSH and ACTH. B-MSH from various species possess additional N-terminal amino acids, and vary in the nature of amino acids 1-3 in the a-MSH structure. Melanocyte-Stimulating Activity.--The ability to produce skin darkening in amphibia has been associated with the pentapeptide sequence 6-10, His- PheArg-Try-Gly, common to both ACTH and MSH. This requirement has now been shortened to the tetrapeptide, His-Phe-Arg-Try ( 6 - 9 ) , which has been shown to possess both melanocyte-stimulating and lipolytic activity at levels comparable to those of the pentapeptide.l6 Alteration in the (6-10) pentapeptide sequence has produced one of the few examples of inhibition by close analogs in the peptide field. The citrulline analog, His-Phe-=-Try-Gly elicits no MSH-activity, but inhibits the activity of a-MSH.I7 Substitution of D-amino acids in the pentapeptide produces compounds which range in activity from MSH-like to antagonists. The all-D isomer, D-His-D-Phe-D-Arg-D-Try-Gly showed no melanocyte-stimulating or lipolytic activity, but lightened the color of a specimen predarkened by either the all-L pentapeptide, or by synthetic a-MSH. Premixture of equal amounts of all-L and all-D isomers blocked the darkening effect on the isolated frog skin.1° The L-D-D-L and L-L-L-D (6-10) peptide sequences

Chap. 1 7

Non-ste roidal H o r m o n e s

193 -

Jorgensen

retained MSH-activity, while the D-D-D-L, L-D-D-D and D-L-L-L analogs were inactive, or weak antagonists.19 The influence of chain length on MSH-activity has been summarized by Schwyzer.20 Synthetic analogs of ACTH, lengthened from the N-terminal to the C-terminal, show initial melanocyte-stimulating activity at the decapeptide (1-101, although the nonepeptide (1-9) was not investigated. Activity increases markedly at the tridecapeptide amide stage, and activity remains constant with further elongation of the C-terminal end. Acetylation of the amino group of the N-terminal serine residue generally enhances activity 10 to 100-fold in the series.

a-MSH ACTH

Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Try-Gly-Lys-Pro-Val-~~ H-Ser-Tyr-Ser-Met-Clu-His-Phe-Arg-Tty-G1y-Lys-Pro-Val1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3

Gly-Lys-Lys-Arg-Arg-Pro-Val-Lys-Val-Try-Pro14 15 16 17 18 19 20 21 22 23 24 NH 1 2 [Asp-Gl y-Glu-Ala-Glu-Asp-Ser-Ala-Glu

1

Ala-Phe-Pro-Leu-Glu-Phe 34 35 36 37 38 39

F2

(Beef) (Sheep)

(Pig)

Adrenocorticotropic Activity.--The total synthesis of B-corticotropin, with the amino acid sequence characteristic of the porcine species, has now been reported in detail.21 The techniques developed have aided the synthesis of smaller fragments which have been used to relate chain length and ACTH activity.20 Corticotropin activity is associated with the presence of a free terminal amino group. From the amino end, threshold activity is found with the 1-13 tridecapeptide amide, corresponding to the free amino form of a-MSH. Four to five amino acid residues after MSH activity has reached its plateau, ACTH activity sets in strongly, reaching an almost constant value at 20-24 residues, then climbing to twice this value at the 39 residues of ACTH. The hexacosapeptide corresponding to the first 26 residues of bovine ACTH has been reported to possess adrenal- and melanocyte-stimulating activtty comparable to the native hormone on a molar basis." Ramachandran, Chung and LiZ3 have pointed out the possible significance of the concentration of all the basic amino acid residues of ACTH in the region between positions 5 and 22, with a solid core (Lys-Lys-Arg-Arg) in positions 15-18. The positive charge contributed by the basic amino acids is considered possibly to contribute to receptor binding with a negatively charged surface. The ten-fold increase in potency from the heptadecapeptide (1-17) to the nonadecapeptide (1-19) may be attributed to the additional arginine at 18, which may contribute a positive charge to receptor binding.

194

Sect. IV - Metabolic & Endocrine


Further enhancement of activity by conversion of the terminal carboxyl group to an amide in this series,24 could be due to the decrease in negative charge contributed by the carboxylate ion, which would interfere with associative interactions at a negatively charged receptor. The approximately equal activity for the octadecapaptide and nonadecapeptide amides was felt to support this concept, 23 since both contained the same core of basic amino acids. The acidic residues concentrated in the carboxyl terminal part of the molecule are suggested as playing a secondary role in enhancing receptor binding at a positively charged site. Since the amino terminal end is most sensitive to alteration, and many functional amino acid residues implicated in the active sites of proteolytic enzymes are present, this region is considered to be the active site of the hormones, oriented by the binding affinities of more distant basic and acidic centers. The importance of the basic amino acids has been further indicated by the essential loss in steroidogenic ACTH-like activit with the hexadecapeptide, cr1’14’ 17-18-Gly1-ACTH, and heptadecapeptide, cr1-T4’ 16-18-G1y1-ACTH-18-N~ in which lysine residues have been removed from the normal 1-18 sequence of ACTH analogs. 2 5 Synthesis of the active analog, 17,18-diornithyl-8-corticotropin(1-24)-tetracosapeptide adds further evidence for the important role of basic amino acids in the 15-18 region of the ACTH molecule.26 Oxytocin and Vasopressin.--BoissonnasZ7 and Lawz8 have published recent comprehensive reviews of structural analogs of these hormones of the posterior lobe of the pituitary.

The following data extends from the structure-activity correlations of Law.28 The question of the importance for hormonal activity of the 20-membered disulfide ring has been investigated further. Analogs of arginine- and lysine-vasopressin and their 1-deamino derivatives in which the ring was open and the S-atoms replaced by H-atoms (e.g , Ala1-Ala6-Arg*-vasopressin) were devoid of hormonal-like or antagonistic activity.29 Additional methylene groups in the ring eliminated activity, as shown by the inactivity of the 21-membered ring compound, 4-8-alanine-oxytocin, when compared with the moderately active 20membered ring analog 4-glycine-oxytocin, and of 1-y-mercaptobutyric acid oxytocin, compared with the highly potent deamino-oxytocin (1-6-mercaptopropionic acid oxytocin) 31 Although the intact 20-membered ring requirement has thus far been upheld, isosteric replacement of the ring atoms is possible with retention of activity. Cyclic analogs of oxytocin in which one of the S-atoms of the disulfide bridge was replaced by a methylene group,32 or by a selenium

.

.

Chap. 17

N o n - s te roidal Hormone s

Jorgensen

195 -

atom (6-seleno-oxytocin and deamino-6-seleno-oxytocin) showed significant hormonal activity. Synthesis of diseleno-oxytocin has been reported, but final purification and biological evaluation was not carried out. 34 The stereochemical relationship between the ring and the side-chain is important, as shown by the loss in oxytocic activity with both 1-hemi-D-cystine- and 6-hemi-D-cystine-oxytocin. All-D-oxytocin has been prepared and shown to lack either hormone-like or inhibiting effects.36 Replacement of L-Tyr2 by D-Tyr2 in oxytocin and its 1-deamino analog produced analogs which retained significant, although slight, oxytocin-like activities as well as an inhibiting effect on oxytocin.37 The analogs L-Dab8- and D-Dab8-vasopressin38, containing the shorter basic sidechain derived from a,y-diaminobutyric acid, showed significant pressor and antidiuretic activities. The D-analog showed selective antidiuretic activity relative to its pressor and uterotonic effects. The configuration of the basic amino acid at the 8-position seems more important for pressor, rather than antidiuretic action, as shown by the selective antidiuretic effects of D-Arg8- and D-Lys8-vasopressin. Alteration of side chains has aided the definition of structural requirements for activity, and has produced analogs with selective and prolonged effects. Both vasopressin and oxytocin show enhancement of activity in the 1-deamino derivatives.40 '41 Systematic replacement by hydrogen of other functional groups in amino acid side chains of oxytocin has shown that the phenolic hydroxyl group is not vital, but does contribute significantly to activity. The carboxamido groups are essential at 5 (asparagbe) and 9 (glycinamide), but not critical at 4 (glutamine), since glutamine may be replaced b a-aminobutyric acid with retention of significant biological a~tivity.~' Removal of the carbox terminal NH2- group alone (9-deamido oxytocin) leads to loss of activity.43 Acylation of the amino end of vasopressin (Gly-Cysl-vasopressin) resulted in a partial reduction in activity, but a three-fold prolongation of effects.43 Preparation of further extended-chain analogs of oxytocin, including Pro-Cysl-, Phe-Cysl-, D-Leu-Cysl-, Leu-Leu-Cysl-, and Gly-Gly-Cysl- oxytocins has been reported.44 The observation of oxytocin-antagonistic properties for analogs of oxytocin with 0-ethyltyrosine, p-methylphenylalanine, and p-ethylphenylalanine replacing t y r o ~ i n e ,has ~ ~ been extended by synthesis of Gly-CyslTyr (Me) 2-vasopressin. This chain-lengthened functionally modified analog showed a small but prolonged antidiuretic effect, and a relatively strong inhibition of the pressor activity of lysine-vasopressin at a molar ratio of analog to hormone of 25:l. Complete and long-lasting inhibition was produced at a ratio of 200:l. Complete inhibition of the uterotonic effect of oxytocin on the isolated rat uterus was obtained at a ratio of 300:1.43 N-Carbamyl-0carbamyl-oxytocin showed no effect alone on the isolated rat uterus, but at an analog to hormone ratio of 50:1, produced complete inhibition of oxytocin administered one minute later. The mono-acylated derivatives, N-carbamyl- and O-carbamyl-oxytocin showed slight oxytocic (0.05 and 0.1%), and no inhibitory effects on the rat uterus.46 The requirements of position 8 have been studied in detail. An aliphatic side chain is important for oxytocic activity, since Gly8-oxytocin was inactive,

196 -

Sect. IV

-



while an ethyl, or even methyl group $resent in But8-oxytocin and Ala8-oxyrocin conferred a high degree of a ~ t i v i t y . ~ The importance of the basicity of the amino acid residue at position 8 and the phenolic group at position 2 for vasopressin-like activity was shown with analogs combining variations at the 2 and 8 positions. Phe2-Om8-vasopressin and Phe2-Om8-oxytocin showed selective pressor activity 48whi1e desaminol-Arg8- and desaminol-Phe2-Arg8-vaso ressins showed an enhanced antidiuretic effect. 49 Syntheses of desaminol -0rn - and desaminol-Phe2-Om8-vasopressins and oxytocins has also been described. Thialysine8-vasopressin, an isostere containing sulfur in place of a methylene group of the lysine side chain, showed antidiuretic activity greater than that of Lys8-vasopressin, with less pressor activity. Therefore, factors other than base strength appear to be involved in the role of the side chain in the 8 position.51 Reaction of oxytocin with acetone under mild conditions to produce an inactive derivative has been noted.52 Reaction is presumed,to occur with the free amino group , since deaminol-oxytocin is not deactivated under these conditions. Specific tritiation of oxytocin by catalytic deiodination has been reported. 53 HORMONES OF THE STOMACH Gastrin.--Heptadecapeptide amides gastrin I and gastrin I1 isolated in 1964 from hog antral mucosa, are believed to be related to the hormone released during digestion, which stimulates gastric secretions. On a molar basis, gastrin I1 is some 500 times more effective than histamine in stimulating gastric secretion. Gastrin I1 differs from gastrin I only in being the sulfate ester derivative of the tyrosine residue.

Pyr-Gly-Pro-Tyr-Met-(Glu)5-Ala-Tyr-Gly-Try-Met-Asp-Phe-NH2 Gastrin I Only the C-terminal tetrapeptide amide sequence, Try-Met-Asp-Phe-NH2 was found to be required to produce the full range of ghysiological effects of the natural hormones. St Structure-activity studiess5’ in the active C-terminal tetrapeptide sequence led to the following observations: (a) all N-acyl derivatives of the tetrapeptide are active, (b) substitution of all, or part of the Lamino acids by the D-isomers leads to virtual loss of activity, (c) replacement of tryptophane by other amino acids results in loss of activity, although 4-, 5-, and 6-methyl tryptophanes are highly active, (d) methionine may be replaced by norleucine or ethionine with retention of activity, byt all changes in the aspartic acid position led to inactive compounds, (e) 0-methyl tyrosine may replace phenylalanine, (f) the terminal amide cannot be converted to the methyl ester, the free acid, or a dialkylamide without loss in activity. TISSUE HORMONES Bradykinin, Kallidin and MethionyJ-ksyl-bradykinin.--Bradykinin and its N-terminal analogs are formed by enzymatic degradation of inactive precursors present in the a2-globulin fraction of plasma. R-Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg 1 2 3 4 5 6 7 8 9 Bradykinin, R = H

Kallidin, R = Lys

Methionyl-lysyl-bradykinin, R = Met-Lys

Chap. 17

N o n - steroidal Hormones

197 -

Jorgensen

From a comprehensive survey of analogs in 1964,57 it was concluded that the importance of individual amino acids for biological activity was in the order, 7,8>1>9>5>4>2>3>6. The Pro7 and Phe8 residues appear to be most essential for biological activity. The terminal arginine residues (1,9) may be replaced with basic amino acids, but neutral amino acids produce a loss of activity. The aromatic residue in position 5 is essential. Exchange of Gly4 and Pro - residues causes medium loss of activity, while the Pro3 and Ser6residues are relatively insensitive to change. The importance of the free carboxyl end of bradykinin, and of other active peptides for full biological activity, has been emphasized.58 Variations in the nature and configuration of the peptide chain have led to less active or inactive analogs. Retrobrad kinin,59 containing the reverse sequence of amino acids, all-

D- bradykininx8'60, and all-D-tetrobradykinin6O showed neither bradykinin-

like nor antagonistic activity. Replacement of either or both of the L-arginine residues with D-arginine resulted in loss of activity, and no production of inhibitory effect.61 Introduction of ester in place of amide links between residues 3-4 and 5-6, in the depsipeptides glycolyl-4- and glycolyl-6-bradybinin produced analogs with 0.5 to 1% activity.62 The inactivity of the c clic decapeptide, Gly7-cyclokallidin, 3as compared with the active linear Gly -kallidin, further demonstrated the importance of conformation for biological activity.

s

A number of octa- and nonapeptide analogs containing threonine in place of serine were prepared as potential antagonist^.^^ Tests on rat uteri showed variable and unpredictable mimetic and antagonistic response; only bradykinin-like effects were seen with the isolated guinea pig ileum or rat duodenum. The solidphase synthesis of b r a d ~ k i n i nhas ~ ~ been extended to provide a number of additional bradykinin analogs. Among these, replacement of both phenylalanine residues with 0-methyl tyrosine yielded an antagonist at low concentrations, but bradykinin-like activity at higher concentrations.66 To date, no bradykinin antagonistic peptide has been reported which is free of bradykinin-like activity at high dose levels. Extension of the N-terminal end of bradykinin generally leads to little change in activity.67 Met-Lys-bradykinin is about 113 as active on isolated muscle preparations, but 2-3 times as active as bradykinin in lowering rabbit blood pressure. The methionine sulfoxide retains the activity of Met-Lys-bradykinin, while the sulfone is only about 1/10 as active. N-terminal-extended bradykinin analogs are generally highly active, with (Lys-Lys-Argl)and (Lys-Lys-Lys-Argl )-bradykinin being 8-10 times as potent as bradykinin in lowering rabbit blood pressure, while being less active in producing contractions

of isolated smooth muscle.

Dihydrochlorprothixene and a related analog have been reported to act as competitive inhibitors of bradykinin on isolated guinea pig preparations. CYPrQheptadine acted as a non-competitive inhibitor. An8iotensin.--Angiotension I, a relatively inactive decapeptide produced by the action of renin on an a2-globulin blood fraction, is converted to the active octapeptide, angiotensin-I1 by the enzymatic removal of a C-terminal dipeptide,

Sect. IV

198

-



His-Leu. Species differences provide two equiactive angiotensins, containing valine or isoleucine in the 5-position. The composition of human angiotensin is not yet established. Asp-Arg-Val-Tyr-Ile 1 2 3 4 5

(Val)-His-Pro-Phe 6 7 8

The kinetics of the renin-substrate reaction have been studied employing a synthetic tetradecapeptide renin substrate. 69 Earlier studies which provided structural relationships relative to smooth muscle-stimulating or pressor effects have been summarized by Law.28 For significant activity, the carboxyl and phenyl groups of Phe8 and phenolic hydroxyl group of Tyr4 appear to be essential. Loss of activity on photolysis and decreased activity of analogs containing 6-substituents supported the essential role of the imidazole ring of His 5 The low activity of the M a 7 analog indicated the importance of Pro7. Substitution of leucine for valine or isoleucine in the 5-position resulted in a four-fold decrease in activity, but leucine could replace Val with complete retention of activity, indicating a selective influence of side chain branching at position 5. A low degree of specificity was generally indicated for Asp1 and Arg2. Aromatic residues (4,6,8).--Using Asp (NH2)1-Val5-angiotensin-II as the parent compound, Schr6der70 has replaced the HisC residue with PhenYlalanine and lYsine+ obtaining activities of 1% and 0.1%, respectively. This provides further evidence for the importance of histidine, with aromatic character apparently being more important than base strength. A surprising loss in activity occurred when 0-methyl tyrosine replaced Tyr4 (0.2%), considering the relatively strong activity reported for the Phe4 analog (10%). Exchan e of hydroxyl groups between positions 4 and 8 with Asp (NH2) 1-Phe4-Va15-Tyr8-angiotensin-II led to inactivity. Apparently the phenolic character of Tyr4 and aromatic character of Phea are the most important features, as shown by the 10% activity of the di-tyrosyl analog, Asp (NH2) 1-Va15-Tyr8-angiotension-II. The closely related Ile5-Tyr8-angiotensinI1 has been reported as only slight1 less active than Ile5-angiotensin-II.71 Increased se aration between the Tyr' and Phe8 residues, by exchange of the Val3 and Tyr residues, led to loss of activity.70

t

r

tes+dues ( 3

~gdrbxyproline%$lace

.--Tyrosine in place of Val3 resulted in 12% activo€ Pro7 reduced activity to 7%.

-Acidic and basic residues (1,2l.--Variations of Asp1 have yielded analogs with

hei htened and prolonged activities. The isomeric a-D-? 6-L- and 6-D-Asp'Val@-angiotensins-II, by comparison with natural a-L-Aspl-Val.'-angiotensin-lI and its Asp1-B-amide, show an increase in activity of about 50%, and a two to three-fold prolongation of pressor activity in the rat. 72 This has been attributed to a decrease in the rate of degradation of the modified angiotensins by Desamino-Val5-angiotensin-I1 showed a 50% decrease, but prolonaminopeptidases ~ ~ showed that gation of activity. This series has been extended by S ~ h r t j d e rwho the D-Asp1-, Glul-, Glu (NH2)l- and Pyroglu1-Va15-angiotensin-II analogs all showed about 50% enhancement of pressor activity over that of Val5-angiotensin11.

.

Chap. 17

Non-steroidal Hormones

Jorgensen

199 -

The activities reported for the Lys2 and Val2 analogs of Asp (~~,)~-Val5angiotensin-I1 (10% and 5 % ) added to the conclusion that the arginine at position 2 is not essential for activity.74 In a study mainly involving 2-8 heptapeptide analogs, X-Val-Tyr-fle-His-Pro-Phe , Havinga’l’’7 6 has concluded that the features of the arginine moiety contributing to activity are the positive charge or the capacity to hydrogen bond of the guanidinium or ammonium groups forming part of X in active peptides. Heptapeptides with D-amino acids in the X-position were more active than the corresponding L-compounds, However, 1-8 octapeptides with D-amino acids in the 2-position were less active than their L-counterparts. All-D-Asp(N€l~~Va15-angiotensin-II has been synthesized as a potential antagonist, but showed neither angiotensin-like nor antagonistic effects in both smooth muscle-stimulation and pressor tests.7 7 97 8

The solid-phase method of peptide synthesis has been used to prepare Ile5-, Asp(NH2) ’-Ile5-, and B-Asp’-Ile5-angiotensins-I1 .79 The problem of the secondary structure of angiotensin in solution is unresolved. Thin-film dialysis studies indicate a coiled or compact form of low axial ratio.80 Biological experiments involving inhibition of smooth muscle responses to angiotensin by urea and amino acids, indicate that the simple compounds produce either randomization of an organized angiotensin structure, or produce inhibition by direct interaction with the receptor.81 MISCELLANEOUS PHYSIOLOGICALLY ACTIVE PEPTIDES

Eledoisin --- -_ .^__ and - Physa1aemg.--The powerful vasodilating hypotensive undecapeptide eledoisin was isolated in 1962 from the salivary glands of a mollusc. In 1964 the four-fold more potent related undecapeptide, physalaemin, was isolated from the skin of a South American amphibian. Eledoisin

H-Pyr-Pro-Ser-Lys-Asp-Ala-Phe-Ile-Gly-Leu-Met-W2

Physalaemin H-Pyr-Ala-Asp-Pra-Asp-Lys-Phe-Tyr-Gly-Leu-Met-M2 1 2 3 4 & 6 7 8 9 1011 5 2

Studies of numerous analogs have shown that similar structure-activity relationships exist in both compounds. The C-terminal amino acids (6-11) are highly sensitive to alteration, while the N-terminal residues (1-5) are relatively insensitive.82 A minimum of five amino acid residues at the C-terminal end (7-11) is needed for appreciable activity, while activity increases sharply with the hexapepti.de (6-11) and higher analogs. The hexapeptide (6-11) related to eledoisin retains 30%;activity in lowering blood pressure in the rabbit, while the heptapeptide (5-11) is essentially as active as e l e d o i ~ i n . ~The ~ corresponding physalaemin hexapeptide (6-11) is 2-2 to 3 . 8 times as active as eledoisin, and at least half as active as physalaemin in its hypotensive effect in the d ~ g . ~ ~a Iseries n of A~p(NH~)~-eledoisinanalogs, maximal h otensive activity in the rabbit was reached in the octa to decapeptide range,T3E while maximal hypotensive activity in the dog was shown at the C-terminal nonapeptide (3-11)

200 -

Sect. IV

-



related to eledoisin.86 Increased activity has been shown in eledoisin analogs with higher thioalkyl groups replacing the thiomethyl group of methionine, while alkylcysteinamide residues, with one less methylene group,or other amino acids, drastically reduce activity.87 The all-D isomer of the highly active hexapeptide analog of eledoisin (6-11) was devoid of either eledoisin-like or antagonistic activity. Systematic replacement of individual L-amino acids by D-amino acids in the active heptapeptide (5-11) resulted in essential loss in activity, except for the D-Ala6 analog, which retained 30% of the activity of the parent heptapeptide, in lowering blood pressure in the rabbit. 88 With few exceptions, both physalaemin and its close analogs are relatively inactive in producing contractions of the rat uterus as compared with eledoisin, in doses equiactive in reducing blood pressure.Q4 THYROID HORMONES Thyroxine and Triiodothyronis.--Recent contributions to studies relating structure and activity may be discussed in terms of the structure of thyroxine.

Phenolic hydroxy1.--Thyroxine-like

activity found for 4'-deoxy-3,5-diiodothyronines, and inactivity for corresponding 4'-methyl analogs was attributed to a probable metabolic introduction of the hydroxyl group to produce the active molecule.89

Outer ring substituents.--The ability of alkyl or aryl groups to replace halogen atoms on the phenolic ring with retention, or even enhancement, of biological activity, has been confirmed. Relative to L-thyroxine (loo), substituted 3,5-diiodothyronines showed the following antigoitrogenic activities in the rat: L-3'-iodo (775), DL-3l-ethyl (3401, L-3'-isopropyl (12501, L-3'-isoproBarker has noted similar potent pyl-5'-iodo (440), and L-3'-isobutyl (60). thyroxine-like effects in oxygen consumption and heart rate tests on rats for thyroxine analogs with outer ring alkyl substituents, or bearing a fused phenyl ring (3,5-diiodonaphthyr0nine).~~ In these tests, as well as a test measuring inhibition of thyrotropic hormone release,91 the 3 ' -isopropyl analog was the most potent tested. 3'-Tertiary butyl-3,5-diiodo-L-thyronine showed equal activity to L-thyroxine in the tadpole metamorphosis assay,92 and about twice the activity of L-thyroxine in the rat antigoiter assay.93 Further examples of decreased activity for outer ring 3',5'-disubstituted analogs, as compared with the correspondine 3'-monosubstituted compound were presented.89 A long standing apparent inconsistency in this regard was resolved by the demonstration that the 3'-chloro analog was more active than 3 ' ,5 '-dichloro-3,5-diiodo-L-thyronine. 94 The importance for biological activity of a distal positioning in space relative to the inner ring for the outer ring substituent has been emphasized by further examples. 89 The role of ring substituents in establishing skewed conformation for the di henyl ether nucleus has been studied on thyroxine analogs using NMR techniques.t 5

Chap. 17

N o n - 8 teroidal Hormones

Jorgensen

201 -

Ether linkage.--Three biphenyl analogs of tetra- and triiodothyroacetic acid, and of thyroxine were found to be essentially inactive in the heart rate test,89 indicating a requirement for the ether linkage. However, the biphenyl analog, 3,5-diiodo-4-(3 ,5 -dimethyl-4'-hydroxylphenyl) phenylalanine was reported to be equiactive to the corresponding diphenyl ether, and about 1.5 times as active as thyroxine in inducing metamorphosis in the immersed tadpole. g6 Iodinated 2-methyl-3-carboxy-5-hydroxybenzofurans, compounds lacking the diphenyl ether nucleus, and previously reported active in the tadpole metamorphosis assay, were inactive in the heart rate test. 89 Inner ring substituents.--The 3,5-dibromo analog of DL-thyroxine approached the activity of thyroxine in the rat oxygen consumption test,89 indicating the lack of a requirement for iodination on the alanine-bearing ring. Thyronines mono-iodinated, or lacking iodine on the inner ring were inactive in oxygen consumption tests. -Side chains.--Thyroxine analogs with alcoholic side chains of varying lengths have been prepared by reduction of the corresponding acids. 97 Among these,

3,5-diiodo-3',5'-dimethyl thyroethanol was reported to show in the rat a greater dissociation between hypocholesterolemic and calorigenic effects than either L- or D-thyroxine. A number of reports of synthesis and biological activities of a-methyl thyronines have appeared. O 0 a-Methyl-DL-thyroxinegg showed weak thyroxine-like activity in antigoitrogenic, cholesterol-lowering, and heart weight assays, and inactivity as a thyroxine antagonist in the antigoiter test. a-Methyl-DL-triiodothyronine and its D- and L-isomers were reported to be more active in the hypocholesteremic test than DL-a-methyl.thyroxine.' O 0

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u.,

m.,

s.,

Chap. 17

54. 55. 56. 57. 58. 59. 60.

61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. 79. 80. 81. 82. 83. 84. 85. 86. 87. 88. 89. 90. 91. 92.

93.

Non-steroidal Hormones

Jorgensen

2 03 -

H. J. Tracy and R. A. Gregory, Nature, 204; 935 (1964). Morley, H. J. Tracy and R. A. G r e F y , Nature, 207, 1356 (1965). J. M. Davey, A. H. Laird and J. S. Morley, J . Chem. SOC. (C), 555 (1966). E. Schrbder and R. Hempel, Experientia, 20, 529 (1964). J. M. Stewart and D. W. Woolley, Nature, 206, 619, 1160 (1965). S . Lande, J. Org. Chem., 27, 4558 (1962). K. Vogler, P. Lanz, W. Lergier and W. Haefely, Helv. Chim. Acta, 49, 390 (1966). E. D. Nicoloides, D. A. McCarthy and D. E. Potter, Biochemistry, 5, 190 (1965). L. Shchukina, G. A. Ravdel, M. P. Filatova, and A. L. Zhuze, Acta Chim. Acad. Sci. Hung., 44, 205 (1965). J. M. Meienhofer, Ann. Chem., 691, 218 (1966). J. M. Stewart and D. M. Woolley, Biochemistry, 2, 700 (1964). R. B. Merrifield, Biochemistry, 2, 1385 (1964). J. M. Stewart and D. M. Woolley, Federation Proc., 24, 657 (1965). E. Schrbder, Experientia, 2l, 271 (1965). J. G. Leme and M. R. eSilva, Brit. J. Phannacol., 25, 50 (1965). D. Montague, B. Riniker, and F. Gross, Am. J . Physiol., *,599 (1966). E. Schrtjder and R. Hempel, Ann. Chem., 684,243 (1965). K. M. Sivanandaiah, R. R. Smeby and F. M. Bumpus, Biochemistry, 5, 1224 (1966). B. Riniker and R. Schwyzer, Helv. Chim. Acta, 47, 2358 (1964). E. Schrader, Ann. Chem., 232 (1966). E. Schrtjder, 680, 132 (1964). E. Havinga, C. Schattenkerk, G. H. Visser, and K.E.T. Kerling, Rec. Trav. Chim., 83, 672 (1964). C. Schattenkerk and E. Havinga, 84, 635 (1965). K. Vogler, R. 0. Studer, W. Lergier, and P. Lanz, Helv. Chim. Acta, 48, 1407 (1965). E. Schrtjder, Ann. Chem., 692, 241 (1966). G. R. Marshall and R. B. Merrifield, Biochemistry, 5, 2394 (1965). L. C. Craig, E. J . Harfenist and A. C. Paladini, Biochemistry, 2, 764 (1964). P. A. Khairallah, R. R. Smeby, I. H. Page, and F. M. Bumpus, Biochim. Biophys Acta, 104,85 (1965). E. Stunner. Ed. Sandrin, and R. A. Boissonnas, Experientia, 20, 303 (1964). E. Schrbder and K. Liibke, Experientia, 20, 19 (1964). L. Bernardi, G. Boisio, F. Chillemi, G. DeCaro, R. DeCastiglione, V. Erspamer, and 0 . Goffredo, Experientia, 22, 29 (1966). K. Liibke, R. Hempel and E. Schroder, Experientia, 21, 84 (1965). L. Bernardi, G. Bosisio, F. Chillemi, G. DeCaro, R. DeCastiglione, V. Erspamer, A. Glaesser, and 0. Goffredo, Experientia, 20, 306 (1964). L. Bernardi, G. Bosisio, F. Chillemi, G. DeCaro, R. DeCastiglione, V. Erspamer, A. Glaesser, and 0. Goffredo, Experientia, 21, 695 (1965). E. Schrbder, K. Liibke, and R. Hempel, Experientia, 21, 70 (1965). S. B. Barker, M. Shimada, and M. Makiuchi, Endocrinology, 76, 115 (1965). 78, 29 (1966). M. Wool, V. S. Fang, and H. A. Selenkow, T. Bauman, G. W. Pipes, and C. W. Turner, 76, 537 (1965). C. M. Buess, T. Giudici, N. Kharasch, W. King, D. P. Lawson, and N. N. Saha, J. Med. Chem., 8, 469 (1965). 533 (1965). E. C. Jorgensen and J. A. W. Reid, J. Med. Chem., J. S o

w.,

m,

u.,

w., w.,

2 04

Sect. IV

-


H e i n e e l m a n , Ed.

94. E. C. Jorgensen and J. A. W. Reid, Endocrinology, 76, 312 (1965). 95. P. A. Lehman and E. C. Jorgensen, Tetrahedron, 21, 363 (1965). 96. M. H. Kullk and J. F. Bester, J. Phann. Sci., 54, 494 (1965). 97. W. J. Wechter, W. A. Phillips, and F. Kagan, J. Med. Chem.,L 474 (1965). 98. DL-a-Methylthyroxlne. Chkmie Grtinenthal, Neth. Appl. 6, 503, 266, Oct. 11, 1965. C.A. 64, 9819d (1966). 99. B. Blank, E. G. Rice, F. R. Pfelffer, and C. M. Greenberg, J. Med.Chem., -9,lO (1966). 100. G. M. K. Hughes and P. F. Moore, Abstract No. 19, Div. Med. Chem., h e r . Chem. SOC. Meeting, Pittsburgh, Pa., March, 1966.

20 5 Chapter 18.

Reproduction

John C . Babcock, The Upjohn Company, Kalamazoo, Michigan Introduction There i s every reason t o b e l i e v e t h a t H i s t o r y will record t h e year 1955 a s one o f those r a r e t u r n i n g p o i n t s i n t h e L i f e o f Man f o r i t was t h e n t h a t t h e f i r s t s t e p s toward e f f e c t i v e family planning and s e l f - c o n t r o l o f population p r e s s u r e s were made; t h e elements o f o r a l contraception began t o take shape. True, it was o n l y a beginning. But it was a beginning b u i l t on a s o l i d foundation, and it o f f e r e d hope: Hope t o young couples not ready t o have children; hope t o o l d e r couples who could ill a f f o r d t o expand t h e i r f a m i l i e s ; hope t o c h i l d r e n where each new mouth t o be f e d would t h r e a t e n f u r t h e r t h e i r s l i m chance f o r s u r v i v a l . And it o f f e r e d hope t o n a t i o n s a l r e a d y s t r a i n i n g every resource i n a f u t i l e e f f o r t t o maintain an a l r e a d y inadequate l e v e l of e x i s t a n c e . A t a t i m e when the laws o f exponential growth were beginning t o t h r u s t populationsinto c r i t i c a l p e r i o d s o f s u r v i v a l , t h e developnent o f o r a l contraception was l o n g overdue. . .and almost t o o l a t e ! ~ r o g e s t e r o n (e 3 ) the hormone o f t h e corpus luteum and fundamental p r e c u r s o r o f most steroid hormones, had been known s i n c e 1 9 2 8 . ~ I t had been i s o l a t e d and synthesized by s e v e r a l research groups by 1934.3 By 1937 i t was known t o block t h e estrus 5 Eight more y e a r s cycle i n t h e r a t 4 and t o block o v u l a t i o n i n t h e r a b b i t . were t o p a s s before hormonal therapy was t o be considered s e r i o u s l y a s a means o f e f f e c t i n g b i r t h c o n t r o l “ and s t i l l t e n more y e a r s before t h e r i g h t s t e r o i d s , i n t h e hands o f some people with imagination.. ..and a plan, produced results o f e x t r a o r d i n a r y importance. Thus Rock, Pincus, and Garcia came t o r e p o r t t h a t o v u l a t i o n could be i n h i b i t e d by administering any o f 1 t h r e e 19-norsteroids o r a l l y between day 5 and day 25 o f t h e menstrual cycle. Like so many important e v e n t s i n h i s t o r y , t h e outcome may have been determined by a f o r t u n a t e coincidence. Both norethynodrel (8) and norethindrone (6b) (which were s e l e c t e d f o r f u r t h e r study) were contaminated with b i o l o g i c a l l y s i g n i f i c a n t amounts o f a n e s t r o g e n i c impurity7 while norethandrolone ( 6 a ) , a weak androgen, capable o f producing s e r i o u s l i v e r dysfunction,’ was not pursued. The corpus luteum and i t s s e c r e t o r y product progesterone, a r e generally held responsible f o r maintaining pregnancy and blocking o v u l a t i o n during t h e extended period o f g e s t a t i o n . A number o f s y n t h e t i c p r o g e s t i n s a r e a l s o recognized t o be e f f e c t i v e o v u l a t i o n i n h i b i t o r s i n animals. I t i s t h e r e f o r e not s u r p r i s i n g t h a t i n v e s t i g a t o r s i n t h e f i e l d considered t h e 19-norsteroids f i r s t s t u d i e d t o be simply “ p r o g e s t i n s . ” ? Unfortunately t h e term continues t o be a p p l i e d erroneously t o o r a l c o n t r a c e p t i v e s i n general, whether containing e s t r o g e n a s an impurity o r as t h e major i n g r e d i e n t i n terms o f b i o l o g i c a l e f f e c t . Actually most c o n t r a c e p t i v e s marketed or under study involve proestrogen, i n combination o r s e q u e n t i a l l y . gestin

-

206 -

Sect. I V

-



Available S t e r o i d Contraceptives Currently, a l l contraceptives marketed contain e i t h e r e t h i n y l e s t r a d i o l (1)o r i t s 3-methyl e t h e r , mestranol ( 2 ) . The former i s a highly potent o r a l estrogen f o r which a l a r g e body o f c l i n i c a l experience e x i s t s . The l a t t e r w a s a contaminant i n e a r l y samples of norethynodrel and norethindrone and i s generally added t o those products i n an amount required t o maint&!za f i x e d composition. I t i s believed t h a t e t h i n y l e s t r a d i o l may be s l i g h t l y more potent than mestranol since 0.05 mg. o f the former and 0.08 mg. of the l a t t e r a r e needed d a i l y t o i n h i b i t ovul a t i o n i n women.’

&- &.CECH

-CZCH

H

CH30‘ 1 Ethinylestradiol

‘ 2 Mestranol

To date, all known progestins a r e derived formally e i t h e r from t h e s t r u c t u r e o f the male hormone testosterone (4a) or from t h e female hormone progesterone (3). Among the former, e t h i s t e r o n e (4b), o r 17e t h i n y l t e s t o s t e r o n e , although t h e o n l y a v a i l a b l e o r a l progestin f o r many y e a r s , l ” has apparent1 not been used i n o r a l contraception. I t has weak androgenic properties.” The 19-nor analo norethindrone (6b), i s . a l s o and i n t h e weakly androgenic, both i n animal s t u d i e s ”jl’ I t s 17-acetate i s generally s i m i l a r i n a c t i v i t y . Norethandrolone ( 6 a ) , f i r s t marketed a s an anabolic agent t o promote weight gain and nitrogen r e t e n t i o n , a l s o e x h i b i t s androgenic p r o p e r t i e s and can produce serious hepatotoxicity over a prolonged period a t high dosage Norethynodwl (8) and norethisterone a c e t a t e a r e r e a d i l y converted t o norethindrone (6b) i n 7Jivo14, 18-21 but the former i s s a i d t o e x h i b i t more estrogenic than androHigh potency was a l s o encountered i n ethynodiol d i genic character. 16y22 a c e t a t e (10) wherein t h e 3-ketone was reduced t o an alcohol2345 and i n 26 l y n e s t r e n o l (12), an analog of 6b i n which t h e 3-ketone has been removed. Numerous r e l a t e d analogs have been prepared and studied, including haloethyriyl and t r i fluoropropynyl d e r i v a t i v e s of 19-norte s t o s t e rone ,27, 28 17chlo roe thynyl-17f3- hydroxye st r-4,9,11- t ri en- 3-one, 29 7a-me t hyl-17-e t h i nyl19-nortestosterone, &, 21-dimethyl-17-ethinyltestosterone (14, Dimethi sterone ) 31 and synthetic 13f3-ethyl-17a-ethinyl-17f3-hydroxygon-4-en-3-one.32

.’

Jd?

d

3 Progesterone

4a 4b

R = H, Testosterone R = CECH, Ethisterone

Chap. 18

Reproduction

Babcoc k

CH3

OH

CH3

6a R = C2H5 Norethandrolone 6b R = CECH Norethindrone

rogesterone 5 Medrox acetag

d

0 4&-xzcH

0’

7a

7b

8 Norethynodrel

X = C 1 Chlonadinone -OAc X = C H 3 Megestrol acetate

AcO’

9 Melengestrol a c e t a t e

&-c-czcH 0 10

Ethynodiol d i a c e t a t e

OH

{!

0

&-

- -0COC 6HL3

,C E C - C H 3

dP l3a R

13b R

05

= CH3 Hydroxyprogesterone =

H

caproat e

tH3

1 4 Dimethisterone

20 7 -

20 8

Sect. IV

-



A powerful stimulus t o t h e development o f o r a l l y e f f e c t i v e analogs o f progesterone was t h e r e c o g n i t i o n o f s u b s t a n t i a l o r a l a c t i v i t y While t h i s material was more p o t e n t t h a n i n 17~-aceto~yprogesteroone?~ e t h i s t e r o n e , it was not widely s t u d i e d because f a r more p o t e n t analogs were r a p i d l y synthesized. O f t h e s e , t h e 6a-methyl d e r i v a t i v e , (medroxyprogesterone a c e t a t e ( 5 ) ,prepared almost simultaneously i n s e v e r a l l a b o r a t o r i e s , 33--35 found wide c l i n i c a l use. Unlike t h e 19-nortestosterone derivat,iws, it has not been a s s o c i a t e d i n c l i n i c a l use with v i r i l i z a t i o n o f t h e f e t u s ( i n c o n t r a s t t o i t s e f f e c t s i n lower s p e c i e s ) nor with h e p a t i c dyso f t h e f e w p r o g e s t i n s which can be used e i t h e r f ~ n c t i o n . ~ I~t ’i s~ one ~ o r a l l y or by i n j e c t i o n . By t h e l a t t e r route, i t forms a m i c r o c r y s t a l l i n e depot from which drug i s a v a i l a b l e for prolonged a c t i v i t y 4 ’ o f up t o s i x months f r o m a s i n g l e i n j e c t i o n . 4 1 34 (n).

I n t r o d u c t i o n o f a A6-bond produces megestrol a c e t a t e i n c r e a s i n g potency s l i g h t l y a 2 and a l t e r i n g t h e metabolic pathway.43-4s i s a l s o a potent The corresponding 6-chloro analog, chlormadinone (7a) p r o g e s t i n used with mestranol i n a s e q u e n t i a l formulation. Other c l o s e l y r e l a t e d 17a-acetoxyprogesterone analogs of i n t e r e s t include t h e 16-methylene compound, melengestrol a c e t a t e (9)48 and t h e 3-desoxy compound DMAP (11).49

26’47

The 1 7 - a c e t a t e group can be replaced with a 17-alkyl roup without loss of a c t i v i t y , both i n 6,1~~-dimethyl-6-dehydroprogesteronegoandi n i t s corresponding 3-hydroxy analog .51 S i m i l a r l y , t h e acetophenonide of lh,17adihydroxyprogesterone i s an e f f e c t i v e s r o g e s t i n and has been s t u d i e d i n a parent e r a 1 contraceptive formulation. It has been estimated t h a t a t l e a s t seven m i l l i o n women i n t h e United S t a t e s a r e c u r r e n t l y using o r a l contraceptives. For most, t h e mechanism of a c t i o n appears t o be suppression of t h e mid-cycle r e l e a s e of LH, preventing ovulation. I n a s m a l l percentage of s u b j e c t s , i n d i r e c t evidence f o r ovulation has been obtained. The combined a c t i o n of estrogen and p r o g e s t i n i n t h e combination i s thought t o produce an endometrium unfavorable f o r implantation and a c e r v i c a l mucous b a r r i e r d i f f i c u l t f o r sperm t o p e n e t r a t e .53 I n t h e s e q u e n t i a l method, e f f i c a c y depends p r i n c i p a l l y on t h e i n h i b i t i o n of ovulation during the period when estrogen i s administered. Recently, l o w doses o f progesterone alane have been r e p o r t e d t o provide a measure of contraceptive efficacy.54 Further r e p o r t s w i l l be awaited with interest S i d e e f f e c t s of t h e s t e r o i d combinations v a r y w i t h t h e i n d i v i d u a l s u b j e c t and t h e p r e p a r a t i o n and may i n c l u d e , b r e a s t tenderness, weight gain, breakthrough bleeding, amenorrhea, f l a t u l e n c e , t i r e d n e s s , nausea......many of t h e symptoms of e a r l y pregnancy. Thromboembolism has not been c l e a r l y r e l a t e d t o use of o r a l contraceptives b u t occasional l i v e r dysfunction, e s p e c i a l l y i n some populations, may be r e l a t e d . 11 a d d i t i o n t o t h e s t e r o i d s used f o r contraception i n t h e female, a number o f s y n t h e t i c hormones resembling t h e s y n t h e t i c estrogens but e x h i b i t i n g a n t i e s t r o e n i c a c t i v i t y i n animals have been s t u d i e d . These i n c l u d (MRL-41), g5 which i s capable of s t i m u l a t i n g ovulation i n some women ;lymiphene U-ll100A,58 and a number of c l o s e l y related analogs.

Chap. 18

Reproduction

20 9 -

Babcock

I n the male as i n t h e female, i n h i b i t i o n of f e r t i l i t y can be produced a r t i ’ i c i a l l y a t many stages. Jackson has reviewed t h e e f f e c t s of agents i n t h e male ( e s p e c i a l l y as studied i n the male r a t ) , and has concluded t h a t while there a r e many opportunities f o r pharmacological control, interference with hormonal mechanisms has r e l a t i v e l y l i t t l e prospect f o r success Research i n t h i s f i e l d can be complicated by the r e l a t i v e l y long period of treatment and study generally required t o observe changes i n spermatogenesis. Some agents, however, l i k e methylene dimethanesulfonate (15) a f f e c t sperm i n t h e f i n a l stages of development and, when used i n experimental animals a t appropriate dosage, can produce prompt development of i n f e r t i l i t y and rapid post -treatment recovery. 6 o Related methanesulfonates i n t e r f e r e with multiple stages of spermatogenesis, suggesting t h a t s e l e c t i v e control at a most appropriate stage may be possible.61

.”

62

63

Certain b a c t e r i o s t a t i c n i t r o f i r a n s (16) and thiophenes (17) were also found t o i n t e r f e r e with spermatogenesis i n t h e male, blocking development a t t h e primary spermatocyte stage. S i m i l a r results,which were r e v e r s i b l e were a l s o obtained with b i s - (dichloroacety1)diamines (18) .64--g6 These materials, which were o r i g i n a l l y studied as amoebacidal agents, were r e l a t i v e l y well t o l e r a t e d i n man,67 e.xcept f o r an ‘Antabuse-like ’ e f f e c t . Another potent agent which blocks spermatogenesis a t t h e primary spermatocyte stage is t h e d i n i t r o p y r r o l e ORF-1616 (19)68 which i s e f f e c t i v e when given once a month.” Hormonal agents, both s t e r o i d a l and non-steroidal, have a l s o been found capable of blocking spermatogenesis. Many e x e r t t h e i r a n t i f e r t i l i t y e f f e c t s through gonadotropin i n h i b i t i o n . When used f o r t h i s purpose, e s t r o gens have the obvious drawback of producing feminization and l o s s of l i b i d o . Androgens have been l o n g k n m t e m p o r a r i l y t o suppress spermatogenesis and i n s e l e c t e d cases, t o produce a rebound i n sperm p r o d ~ c t i o n . ~ 7’ 2 A number of progestins have r e c e n t l y been evaluated i n the male, including norethandrolone (6a) and 17a-hydroxyprogesterone caproate (l3a).72 These agents i n h i b i t Leydig c e l l function and gonadal hormone production. Medroxyprogesterone a c e t a t e (5)33 a potent progestin e f f e c t i v e both o r a l l y and p a r e n t e r a l l y , was observed t o produce a marked decrease i n sperm count and m o t i l i t y l a s t i n up t o s i x months when given as a s i n g l e 1000 mg i n j e c t i o n t o male v o l ~ m t e e r s . ’ ~ The long duration of a c t i o n of t h i s progestin i s t h e r e s u l t of t h e formation of an intramuscular depot of slowly released drug when administered as a microcrystalline aqueous suspension by t h e intramuscular route.

Clomiphene (MRL-41), an agent which can induce ovulation under some conditions i n women, i n h i b i t s t e s t i c u l a r and accessory gland weights i n t h e when administered male r a t t o t h e range seen a f t e r h y p o p h y s e ~ t p m y . ’ ~ , ~However, ~ o r a l l y to7goung men i n doses of 50-200 mg/day, clomiphene stimulated Leydig c e l l A b i o l o g i c a l l y s i m i l a r dihydronaphthalene d e r i v a t i v e , U - l l l O O A (21) ,58 functior,. w a s found t o i n h i b i t spermatogenesis at a dose of 0.5 mg/kg i n t h e rabbit.75 The hydrazine d e r i v a t i v e I C I 33828 (22) a l s o i s e f f e c t i v e i n both male and female r a t s and i n other species and has been studied i n

Sect. IV

210 -

- Metabolic

& Endocrine


C12CHCONH- (CH2)8-NHCOCHCl, Win 18446

(18)

ICI

33828 (22)

CH3 O /

U-lllOOA (21)

Among n u t r i t i o n a l f a c t o r s a f f e c t i n g f e r t i l i t y , t,he r o l e of Vitamin E and A have r e c e n t l y been r e v i e ~ e d . ~ ~ J ~ ~ The r a p i d l y developing knowledge of immunological phenomena as app l i e d t o f e r t i l i t y and i n f e r t i l i t y has a l s o been reviewed79J80 and can conf i d e n t l y be expected t o provide important new approaches during t h e next decade

.

Chap. 18

Babc oc k

Reproduction

21 1

Eeferences J . Rock, 0. P i n c u s , and C. R . G a r c i a , S c i e n c e , 891 (1956). G. W. Corner i n "Progesterone" A . C. B a r n e s , e d . Brook Lodge P r e s s , Augusta, Mich. 1561, P. 3. 3. For a summary of t h e s e e v e n t s and survey of p r o g e s t a t i o n a l a g e n t s , s e e L. F i e s e r and M. F i e s e r " S t e r o i d s " Reinhold Publ. Corp., New York 1959, p. 556. h. H. S e l y e , J. S. L. Browne and J. B. C o l l i p , E .&. E. 472 (1936). 512 (1937). 5. A. W. Makepease, I;. L. Weinstein and M. H. Friedman, &I. J . P h y s i o l . , 6. F. A l b r i g h t i n " I n t e r n a l Medicine i t s Theory and P r a c t i c e . " ed. J. H. Musser, Lea and F e b i g e r , P h i l a . 1945. 323 (1957). 7. a)) J. Rock, C . R . G a r c i a , and G. P i n c u s , Recent Progr. Horm. g . , b ) G. P i n c u s , J. Rock, and C. R . G a r c i a , Ann. N Y Acad. 72, 677 (1958). &', 307 (1959). c ) G. Pincus, vita=. 8. I . M. A r r i a s , N Y Acad. &. , 124, 1014 (1963). 9. E. Mears i n "Agents A f f e c t i n g F e r t i l i t y " , ed. E. C . R a n s t i n and J . S. P e r r y , C h u r c h i l l , London, 1966, p. 211. 10. H. II. I n h o f f e n , W. Logemam, W. Hohlweg, and A . S e r i n i , Ber. 71, 1024 (1938). 11. L. Wilkins. J . &. @. lJ2, 1028 (1960). 12. V. A. D r i l l , J. Endoc-inol., .2?, x v i i (1962). 13. R. L. E l t o n , E. F. N u t t i n g , and W. E. Saunders. Endocrinol., 381 (1962). 14. R . W. K i s t n e r , C l i n . Pharm. Therap., 1,525 (1960). 15. R. W. K i s t n e r , Marquette K., 59, 2 (1963). 16. Lebher-z, s e e r e f . 14. L. 1 (1961). 17. R. W. K i s t n e r , 18. G. Betz and J. Warren. New Eng. J . , &8, 1171 (1963). l8, 1040 (1959). 19. V. A. D r i l l , F A . S., 20. D. A. McGinty and C. D i e r a s s i , Ann NY Acad. E., 500 (1958). 21. H. J. Ringold, A n n N Y . e . 4 . 515 (1958). 22. H. S. Kupperman, UP. 2_5,86 (1962). 23. F. B. Colton and P. D. K l i m t r a , I n t e r n a t i o n a l Congress on Hormonal S t e r o i d s , l s t , Milan, L. M a r t i n i and A. P e c i l e , e d s . (Academic P r e s s , New York, 1965) v o l . 2 , p. 23. 24. G. P i n c u s , C . R . G a r c i a , M. Panigua and J . Shepard, S c i e n c e , 2 8 , 439 (1962). 25. G. Pincus, Advances Chemistry 45, 177 (1964). 26. X. S. d e w i n t e r , C . M. Siegmann, aiih S. A . S z p i l f o g e 1 , e . (London), x 9 , 905. 157 (1964). 27. V. Petrow, Rep. P r o g . &. 28. J. C . Babcock, Advances & Chemistrx, l9O (1964). 29. J . H. F r i e d , T. S . Bry, A . E. O b e r s t e r , H. E . B e y l e r , T. B. Windholz, J . Hannah, L. H. S a r e t t , and S . L. Steelman, J . &. g . ,L3, 4663 (1961). a 6 , 800 (19641. 30* G. W. Duncan, S. C . L y s t s r and J. A. Campbell, E.g. Pharmacol., 929 (1557). 31. A . David, F. H a r t l e y , D. R . N i l l s o n , and V . Petrow, J . ??. 8 . A . Edgren, H. Smith, D. L. P e t e r s o n , and D. L. C a r t e r , S t e r o i d s , &, 319 (1963). f3. J. C . Babcock, E. 9. G u t s a l l , M . E. H e r r , J . A. Hogg, J . C. S t u c k i , L E . Barnes and W. E . D u l i n , J. 5.chk. G . ,L O t O . 2904 (1958). 34. H. J. Ftingold, 3 . Perez R w l a s , E. B a t r e s , C . D j e r a s s i , J . &I. 3712 (1959). 1959, 478. 35. P. P . E a r i o n , B. E l l i s , V. Petrow, 2. 56. .7. W. Goldzieher, Texas 2. 57, 962 (1961). .I J . Obst. Gynecol., k 6 , 882 ( 1 9 6 3 ) . 57. J. W. Goldzieher and K . Rodgers, & 38. W. J. Rawlings, Brit. J., 336. 873 (1963). 39. F. P . Rhoades, J . 40. M. L. Helmreich and R . A. Huseby, S t e r o i d s , Suppl. 11, 79 (1965). 41. Unpublished S t u d i e s . 42. H. ,i. Ringold. E. R a t r e s . A . Eowers, J . Edwards, J . Z d e r i c . J . &. g. , 81, 3485

1.

2.

=.

w., 3, 3,

-

&.

2,

m.,

e.,

-

e.,

e.

m. z.m., 5,

51,

=.

2,

m.,2,

-

u.

u, 3,

3,

e.

x.e. m., s. 2,

e. m.,

E., w. 1962,

m. e., Ll,

?_

m. m. e., 62,

43. 44. 45.

=.

(1959).

k,

J . M. Cooper, H. E. 9. J o n e s , and A. E. K e l l i e , S t e r o i d s , 255 (19651. B. A . Cooke and D. K. V a l l a n c e , Biochem. J . , 3 l p (1964). B. A. Cooke, T. J . McDonald and D. K. V a l l e n c e . Biochem. J. % , 2 5 p (1965).

z,

-

212

Sect. IV

- Metabolic & Endocrine


I?. J . Ringold, E. Batres. A. Bowers, J . Edwards, and J. Zderic.

47.

J.

48.

G. R. R.

D. J.

53.

a)

54.

b) J.

55.

D.

56.

S.

57.

G.

58. 59.

D. H.

60.

B.

62.

w.

61.

63. 64.

65. 66. 67. 68. 69.

H.

E. A. F.

w. c.

G.

D.

70.

C.

71:

c. c.

72.

E,

u,

=.

e.,

---

(2)

~

a. &.

2.

2,

s. a. e. 3, m.

e.,

79.

s.

80.

A.

e. *.

9. &. ,5 1 , 3485 (1959). Zderic i n Comprehensive Biochemistry, M. F l o r k i n and E. H S t o t z , ed. E l s e v i e r 166. Publ. Co., New York. 1963 p. W. Duncan. S. C . L y s t e r , J . W. Hendrix, J. J. Clark, and H. D. Webster, F e r t l l . and_ 419 (1966). Steril. P. Blye. V. R . B e r l i n e r and R. E. Horn, Fed. , &, 701 (1965). Deghenghi and R. Gaudry, 2. &. -. E.& ,8 4668 (1961). J . lularshall, P. F. Morand, C. Revesz. and R . Gaudry, 2. E. 7, 355 (1964). F r i e d , E. F. Sabo, P. Grabowich. L. J. Lerner, W. B. Kessler, D. M. Brennan, A. Borman. Chem. and Ind. (London), 465 (1961). 0. Pincus i 7 n Agents Affecting Fertility'!,C. R. Austin and J. S. Perry, ed. Churchill, London, 1965, p. 195. E. Diczfalusy, E .K . 2.. 1394 (1965). Martinez-Manautoil, V. Cortez, J. Oiner. R. Aznar, J. Casasola. and H. W. Rudel, Pert. and S t e r i l . , 1 ~ , 4 9 (1966). E. Holtkamp. J. G. Greslin. C. A. Root, and L. J. Lerner, @. Biol.Ided., 125. 197 (1960). Roy. R. B. G r e e n b l a t t , V. B. Mahesh, and E. C. Jungck, F e r t i l . and S t e r i l . , 575 (1963 1. I. M. Swyer i n "Agents Affecting F e r t i l i t y " . C. R. Austin and J. S. Perry, ed. Churchill, London 1965, p. 180. Lednicer, J. C. Babcock, S. C. Lyster and G. W. Duncan, M. E. (London) 1 2 3 , 408. Jackson i n "Agents Affecting F e r t i l i t y " . C. R. Austin and J. S. Perry, ed. Churchill, London 1965, p. 62. W. Fox and H. Jackson, c i t e d i n r e f . 59. Jackson, B. W. Fox. and A. W. Craig, 2. Reprod. F e r t i l . , 3, 447 (1961). 0. Nelson and E. S t e i n b e r g e r , Fed. Proc., 103 (1953). E.,9 ,312 (1956). S t e i n b e r g e r , W. 0. Nelson and A. Boccabella. R. Surrey and J. R. Mayer, 2. & Pharm. I . Chem., 3 4 0 9 , (1959). Coulston, A. L. Beyler, and H. P. Drobeck. Toxicol. Pharmacol., 2 , 715 (1960). 0. Nelson and D. J. Patanellf,, Fed. 418,1961. G. Heller. B. Y . F l a g e o l l e , and L. J. Matson, E. P a t h o l . , 2 , 107 (1963). Karmes. Abst. 144th Meeting American Chemical Society. p3lL (196fl. J. P a t a n e l l i and W. 0. Nelson, Recent Progress Hormone Research, 0. Pincus, ed. Academic P r e s s , New York. 1964, p. 491. G. H e l l e r , W. 0. Nelson, I. B. H i l l . E. Henderson, W. 0. Maddock. E. C. Jungck, C. A. Paulsen. and G. E. Mortimore, F e r t i l . and S t e r i l . , 1. 415 (1950). w W. Charney, F e r t i l . and S t e r i l . , 10, 557 (1959). G. E e l l e r i n "Estrogen Assays i n Z i n i c a l Medicine", C. A. Paulsen ed. Univ. Washington P r e s s , S e a t t l e (1965). p. 283. MacLeon i n "Agents Affecting F e r t i l i t y " , C. R . Austin and J. S. Perry, ed. Churchill, London 1965, p. 93. 0. Nelson and D. J . P a t a n e l l i i n "Agents Affecting F e r t i l i t y " . C. R . Austin and J. S. Perry, ed. C h u r c h i l l , London 1965, p. 78. J . Eriasson, Fed. & TOO (1965). L. Walpole i n "Agents Affecting F e r t i l i t y " . C. R. Austin and J. S. Perry, ed. Churchill, London 1965. p. 159. Moore i n "Agents Affecting F e r t i l i t y " , C. R. Austin and J. S. Perry, ed. Churchill, London 1965, p. 18. N. Thompson, J . M. C. Howell and 0. A . J . P i t t i n "Agents Affecting F e r t i l i t y " , C. R . Austin and J. S. Perry, ed. Churchill, London 1965, p. 34. J . Behrman i n "Agents Affecting F e r t i l i t y " , C. R. Austin and J. S. Perry, ed. Churchill, London 1965. p. 47. Tyler and D. W. Bishop i n "Immunological Phenomena", Pergamon Press, New York, 1961, Chapt. 8.

46.

-

Chap. 19

Chapter 19.

Steroid Hormones

Diassi and L e r n e r

213 -

S t e r o i d Hormones and t h e i r Antagonists

P a t r i c k A . D i a s s i and Leonard J. Lerner, The Squibb I n s t i t u t e f o r Medical Research, New Brunswick, N . J . A c a t a l o g of b i o l o g i c a l l y a c t i v e s t e r o i d s which have appeared i n t h e s c i e n t i f i c and p a t e n t l i t e r a t u r e through 1963 has been published.'Y2 The following is a review of t h e more a c t i v e s t e r o i d s and steroid-hormone a n t a g o n i s t s which have been published recently.

Corticoids C o r t i c o i d s have a s t h e i r primary c l i n i c a l u t i l i t y t h e c o n t r o l of inflammation. Recent reviews of this and o t h e r r e l a t e d a c t i v i t i e s of c o r t i c o i d s have been published. 3-7 S e v e r a l new 16a-halocorticoids have been synthesized, of which 16a-chloro601,9a-difluoroprednisolone 21-acetate (1) i s 1,100 times a s p o t e n t a s hydrocortisone i n i n h i b i t i n g granuloma formation i n r a t s when administered subcutaneously. S e v e r a l 17-desoxycorticosteroids, including 16a-methyl-1-dehydrocorticosterone ( 2 ) and t h e i r 6af luoro-10 and 9a-f l u o r o - d e r i v a t i v e s (2a and 2 b ) , 9 have been prepared and t h e i r c o r t i c o i d a c t i v i t y measured.

214

Sect. IV

-


Heinzelman, Ed.

Comparison of the thymolytic activity of some new 21chlorosteroids with the corresponding 21-hydroxy compounds has shown11 the danger of projecting the biological relationship of one series of steroid compounds into another. The mechanism of the anti-inflammatory action of steroid hormones remains obscure; however, the regulatory effect of corticoids on metabolism may be an important factor.12-14 Additional reports15-17 have been made on the thymolytic action of corticoids. The antiglucocorticoid activity of 1-dehydrotestololactone on cortisone acetate without inhibition of antigranuloma or thymolytic activity has been reported,6 Reviews on antialdosterone compounds have been published. 18,l9 There is as yet no known potent naturally-occurring,sodium-losing steroid.20 Progestational Compounds Progestational agents have been tested for many biological criteria, several of which are translatable into clinical utility.21-23 Among these criteria are the proliferation of the uterine endometrium, maintenance of pregnancy in the overectomized animal and inhibition of ovulation. In general, synthetic compounds are initially evaluated in the ClaubergZ4 or the modified Clauberg ( M a ~ P h a i l )assays. ~~ It is difficult to compare activities reported from many laboratories because of variation in method, route of administration and reference standards. A number of new progestational1 active compounds have been reported. The 21-fluoro-derivative 3aT6 of chlormadinone ( 3 ) is approximately 1.5 times as active orally as 3 in the Clauberg assay, and the 3p-acetoxy compound 427 is 100 times norethindione by oral administration. The 7-dehydro-derivative 5a of medroxyprogesterone (5) has been synthesized28 and has an improved ovulation inhibiting/progestational index. The totally synthetic 4,9,11-trienes 6 and 6a have been found29 to be orally as active as is progesterone administered subcutaneously. A number of retrosteroids have also been prepared,30 the most active being the 6-fluoro-6-dehydro compound 7. The l7a-vinyl compound 8 has been compared31 to norethynodrel (9) with regard to progestational activity. Both compounds demonstrate the same spectrum of activities, although 8 has slightly higher progestational activity and lower estrogenic activity than norethynodrel.

Chap. 19

Steroid Hormones

21 5 -


Salts of steroids have been found to have progestational activity on oral administration. These include the 3-ammonium sulfate 10 and the 3-pyridinium sulfate 11.32 The 38-(1pyrrolidy1)-derivative 1233 and the tricyclic compound 1334 also have progestational activity. CH2X

I c=o

3 3a

X= H

6a

C=O

C=O

5 5a

4

X=F

R=H R = CH3

~7

y 3

c=o

OH

8

7

9

R = CH=CH2 R = C=CH

CH3

CH3

I

I c=o

10

y 3

I

CH3 I C"0

6

CH3

CH3

1

c=o

11

c=o

12

21 6 -

Sect. IV

- Metabolic & Endocrine


13 Androqens Androgenic steroids, in addition to having an effect on the growth and secretion of sex organs and accessory sex organs, produce effects on other tissues. These include bone, muscle, 3 5 36 ~ blood, lymphatic system, hair and skin. Recent on this subject, as well as on the clinical utility of androgens, have been published. Several new structural types have been shown to have androgenic activity. These include the 19-nor-retrosteroid 14,37 the tricyclic acids 15 and 16,3* the 17-pyrrolidinium tosylate 1739 and 6-methylandrost-5-ene-3~-01-17-0ne (18).40

OH *=.-

COOH

....CH2CH3 0

14

15 A4 16 A1

17

18

Chap. 19

Steroid Hormones

217 -

Diassi and Lerner

A number of compounds have been synthesized in an attempt to separate the anabolic activity of androgens from their virilizing properties. These include testosterone 17f3-adamantate (19),41 the retrosteroids 2042 and 21,43 the 3,3-azosteroid 22,44 the 2,3furazan 23,45 la,7a,17a-trimethyltestosterone 2446 and substituted 17B-tetrahydropyran-2-yl ethers,47 all of which have good dissociation quotients.

0-c I

OH

OAc

X

20 21

19

x=c1, X=F

22

A126

OH

23

OH

24

The biological properties of antiandrogenic steroids as well as their possible clinical utility has been reviewed. 35948~49 As a rule, progestational compounds as well as a number of weak androgenic compounds have shown antiandrogenic properties. Synthetic efforts have been directed to separate hormonal properties from antiandrogenic activity. Among the recently synthesized compounds which have antiandrogenic activity are 17,17-dimethyl-18norandrosta-4,13-diene-3-one (25),50 the 17a-ethyl-19-nor- compound 26,51 3B-seleno~teroids~~ and the tricyclic compound 13.34 The

218

Sect. IV

-



A-nor steroids 2753 and 2854 continue to show antiandrogenic activity which has been characteristic f o r this series, and the B-nor steroid 29553 56 shows similar activity. The 16a-bromo17-ketal 3055 had significant antiandrogenic activity in the testosterone-stimulated mouse. An example of a potent progestational compound which has strong antiandrogenic properties is the l,2-methylene compound 31.48~57 CH3

OH

OAc

OH 25 26

R=R'= CH3 R = H , R'=C2Hg

28

27

7 3 OH

c=o

....Br

0

Cl 29

30

31

Estrogens Recent reviews on estrogens and antiestrogens have been published .48~ 58-60

The 2-chloroethoxy ether 32 and the 2-fluoroethoxy ether 32a have shown61 estrogenic potencies in the mouse uterine assay of 4 times estrone when administered orally but only 0.5 and 0.05 times estrone on subcutaneous administration. The pentacyclic

Steroid Hormones

Chap. 19

219 -


phenol 33 administered t o t h e c a s t r a t e female mouse exhibited62 e s t r o g e n i c a c t i v i t y of 1/4000 t h a t of e s t r o n e . A number of C-19 f u n c t i o n a l s t e r o i d s 6 3 a l s o show weak e s t r o g e n i c a c t i v i t y .

& I

CH30

32 32a

P OH

0- CH2-CH2X

HO

x=c1

33

X=F

The l i p o d i a c t i c - e s t r o g e n i c r a t i o has been determined f o r a number of 3-desox e s t r a t r i e n e s , a n d t h e 4-methyl compound 34 has a r a t i o of 150.g4 S e v e r a l o t h e r compounds have been s t u d i e d f o r their e f f e c t on blood l i p i d s . These i n c l u d e t h e 168,178pyrazoline 35,65 t h e 2-methoxymethyl compound 36,66 t h e 138-ethyl compound 37 ,G7 t h e androstane-2-propionic a c i d 3868 and s e v e r a l 1-methylequilenine compounds.69 A l l of t h e s e compounds lower blood c h o l e s t e r o l . NH2 I

c-s I

OH

0

34

cp3

36

35 OH

37

t

CH3

38

220 -

Sect. IV

- Metabolic &

Endocrine

H e i n e e l m a n , Ed.

Corticoids, sex hormones and nonhormonal compounds are known to inhibit the biological activity of estrogens. A compound which shows both antiandrogenic and antiestrogenic properties is 26.51

Steroid Hormones

Chap. 19


221 -

References

1. 2. 3. 4. 5. 6.

7. 8. 9. 10.

11. 12. 13. 14. 15. 16. 17. 18. 19.

20. 21.

N . Applezweig, " S t e r o i d DrUgs,l' McGraw-Hill, New York, 1962. N . Applezweig, " S t e r o i d Drugs 11," Holden-Day Press, San Francisco, 1964. L. H. S a r e t t , A . A. P a t c h e t t and S. L. Steelman, " F o r t s c h r i t t e d e r Arzneimittelforschung," Vol. 5, Birkhauser Verlag, Basel and S t u t t g a r t , 1963. I . E. Bush, Pharm. R e v . , $ 4 & J l, 317 (1962). I . R i n g l e r , "Methods i n Hormone Research," Vol. 111, R . I . Dorfman, Ed., Academic Press, N.Y., 1964, pp 227-336. L. Lerner, A . Bianchi, A. R. Turkheimer, F. M. S i n g e r and A . Borman, A n n . N.Y. Acad. S c i . , 1071 (1964). C. A . S c h l a g e l , J . Pharm. S c i . , 5 4 ( 3 ) , 335 (1965). F. Kagan, R . D . Birkenmeyer and B. J. Magerlein, J . Med. Chem., w 7 , 751 (1964). D. Brancini, G . Rousseau and R. Jequier, S t e r o i d s , 6 ,451 (1965). A . Domenico, H. Gibian, U . Kerb, K. K i e s l i c h , M. Kramer, F. Neumann and G. Raspe, A r z n e i m i t t e l f o r s c h . , 46 (1965). M. H e l l e r , R . H. Lenhard and S. B e r n s t e i n , S t e r o i d s , 615 (1965). L.Kostyo, Endocrinology, 76, 604 (1965). Q. T . Smith and D. J. A l l i s o n , Endocrinology, 785 (1965). A . Kekwick and G . L. S. Pawan, J. Endocrin., &, 265 (1965). P . H. Wiernick and R . M. MacLeod, Acta Endocrin., 138 (1965). R . I . Dorfman, P . G. Holton and F. A . Kincl, Acta Endocrin., 49, 262 (1965). .wI L. Angervall and P. M. Lundin, Acta Endocrin., 3, 104 (1965). C. M. Kagawa, "Methods i n Hormone Research,' Vol. 111, R . I . Dorfman, Ed., Academic Press, N.Y., 1964, pp 351-404. R. Gaunt, J. C h a r t and A. A . Renzi, " R e v i e w s of Physiology, Biochemistry and Experimental Pharmacology," Springer-Verlag, B e r l i n , Heidleberg, New York, 1965, pp 114-172. J. M. George, G . S a u c i e r and F. C . B a r t t e r , J. C l i n . Endocrin., 621 (1965). T. Miyake, "Methods i n Hormone Research," Vol. 11, R. I. 1962. Dorfman, Ed., Academic Press, N.Y.,

J.

u,

u,

u,

J.

u,

J.

a,

a,

222 -

22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44.

45. 46. 47. 48.

49.

Sect. I V

- Metabolic

& Endocrine


J. C. Babcock, "Molecular Modification in Drug Design,"

Advances in Chemistry Series, No. 45, American Chemical Society, Washington, D.C., 1964, p. 190. M. S. Kufferman, "Human Endocrinology," Vol. 1-3, F. A. Davis Co., Philadelphia, Penna., 1963. C. Clauberg, Zentr. Gynaskol., !j4, 2757 (1930). 145 (1934). M. K. MacPhail, J. Physiol. (London), R. F. Church and M. J. Weiss, J. Med. Chem., 8, 386 (1965). Y. Lefebvre and R. Gaudry, Canad. J. Chem., 1990 (1965). G. Cooley, B. Ellis and V. Petrow, Tetrahedron, 1753 (1965). G. Nomine, R. BucOrt, J. Tissier, A. Pierdot, G. Costerousse and J. Mathieu, C.R. Acad. Sci. (Paris), 4545 (1965). J. Hartog and P. Westerhof, Rec. Trav. Chim., g,918 (1965). P. de Ruggieri, R. Matscher, C. Lupo and G. Spazzoli, Steroids, A, 73 (1965). R. Deghenghi and C . Revesz, J. Endocrin., 301 (1965). A. P. Shroff, J. Med. Chem. , 8, 881 (1965). A. Boris, Endocrinology, 3, 1062 (1965). "Methods in Hormone Research," Vol. I1 and 111, R. I. Dorfman, Ed., Academic Press, New York, N.Y. A. Segaloff, "Molecular Modification in Drug Design," Advances in Chemistry Series, No. 45, American Chemical Society, Washington, D.C., 1964, pp 204-220. J. M. H. Graves, G. A. Hughes, T. Y. Jen and H. Smith, J. Chem. S O C . , 5488 (1964). L. Mamlok, A. Horeau and J. Jacques, Bull. SOC. Chim. France, 8, 2359 (1965). 3203 (1965). R. M. Scribner, J. Org. Chem., E. Howard, Steroids, 255 (1965). R. T. Rapala, R. J. Kraay and K. Gerzon, J. Med. Chem., &, 580 (1965). P. Westerhof and J. Hartog, Rec. Trav. Chh., 918 (1965). P. Westerhof, J. Hartog and S . J. Halkers, Rec. Trav. Chim., 863 (1965). R. F. Church, A. S . Kinde and M. J. Weiss, J. Am. Chem. SOC., 2665 (1965). M. Shimizu, G. Ohter, K. Keno, T. Takigoshi, Y. Oshimia, A. Kasahara, T. Onodera, M. Mogi and H. Tachiyawa, Chem. Pharm. Bull. (Tokyo), g , 895 (1965). F. Neumann and R. Wiechert, Arzneimittelforschunq, 1168 (1965) A. D. Cross and I. T. Harrison, Steroids, Q , 397 (1965). L. J. Lerner, "Recent Progress in Hormone Research,'* Vol. 20, G. Pincus, Ed., Academic Press, New York, N.Y., 1964, p. 435. R. I. Dorfman, Acta Endocrin., G ,40 (1965).

a,

u,

a, m,

a,

a,

a,

a,

a,

a,

Chap. 19

50.

51. 52. 53.

A. R. A. L.

54.

L.

55. 56.

R. H.

57. 58.

F.

59.

R.

60.

G.

61.

A.

62. 63. 64.

J.

M. A.

65.

R.

66.

K.

67.

H.

68.

L.

69.

A.

C.

Steroid H o r m o n e s

D i a s s i and L e r n e r

5,

223 -

Segaloff and R . B. G a b b a r d , S t e r o i d s , 433 ( 1 9 6 4 ) . Y. K i r d a n i and R. I . D o r f m a n , J . Med. Chem., 8, 268 ( 1 9 6 5 ) . Segaloff and R . B. G a b b a r d , S t e r o i d s , 2, 2 1 9 ( 1 9 6 5 ) . J. Lerner, A. V. B i a n c h i , M. D z e l z k a l n s and E . D z e l z k a l n s , S t e r o i d s , 5, 2 2 3 ( 1 9 6 5 ) . J. Lerner, A . V. B i a n c h i , M. D z e l z k a l n s and E . D z e l z k a l n s , Steroids, 5, 215 ( 1 9 6 5 ) . I . D o r f m a n , J . Fajkos and J. Josha, S t e r o i d s , 1, 675 ( 1 9 6 4 ) . L . Saunders, K. H o l d e n and J . F. K e r w i n , S t e r o i d s , 2, 687 ( 1 9 6 4 ) . N e u m a n n and K. Junkmann, E n d o c r i n o l o q y , -, 7 3 33 ( 1 9 6 3 ) . w. Emrrsens and L . M a r t i n , "Methods i n H o r m o n e R e s e a r c h , " V o l . 111, R . I . D o r f m a n , E d . , A c a d e m i c Press, New Y o r k , 1964, pp 1-75. N.Y., I . D o r f m a n , "Metabolic I n h i b i t o r s , " V o l . 1, A c a d e m i c Press, New Y o r k , N.Y., 1963. P i n c u s , "The C o n t r o l of F e r t i l i t y , 'I A c a d e m i c Press, New Y o r k , N.Y., 1965. D. C r o s s , E . D e n o t , H. C a r p i o , R . A c e v a d o and P. C r a b b e , Steroids, 557 ( 1 9 6 5 ) . M. G r a v e s and H. J . R i n g o l d , S t e r o i d s ( S u p p l . I ) , (1965). 2553 ( 1 9 6 5 ) . E . W o l f f and T. Morioka, J. O r g . C h e m . , H. G o l d k a m p , W. M. H o e h n , R . A . Mikulec, E . F. N u t t i n g and D. L . C o o k , J. M e d . Chem., 409 ( 1 9 6 5 ) . E . Schaub, J. H. van den H e n d e and M. J. Weiss, J. O r g . 2234 (1965). Chem. , N a k a m u r a , Y. Matsuda, K. N a k a t s u j i , T. H i r o o k a and K. F u j i m o t o , J. A t h e r o s c l e r . R e s . , 5, 420 ( 1 9 6 5 ) . S m i t h , G. A . H u g h e s , G. H. D o u g l a s , G. R . Wendt, G. C. B u z b y , R . A. E d g r e n , J . F i s c h e r , T . F o e l l , B. G a d s b y , D. H a r t l e y , D. H e r b s t , A. B. Jansen and K. Ledig, J. Chem. SOC., 4472 ( 1 9 6 4 ) . C h e v i l l a r d , C . B o u r n i q u e , H. K a g a n and R . P o r t e t , Therapie., 371 ( 1 9 6 5 ) . C o r b e l l i n i , G. G e r a l i , G. F e r r a r a and G. Lugaro, F a r m a c o ( S c i . ) ,3 ! , l 1044 ( 1 9 6 4 ) .

3,

a,

g,

a,

a,

2 24

Sect. I V

-

Metabolic & E n d o c r i n e


Chapter 20. Non-steroidal Antiinflammatory Agents Robert A. Schemer, Parke, Davis and Company, Ann Arbor, Michigan

Introduction. Non-steroidal antiinflammatory ( A I ) agents a r e of i n t e r e s t f o r t h e management of inflammation and pain i n scores of rheumatic and other inflammatory conditions. Some may be found useful a s a n t i asthmatic agents.' The l a s t few years have seen a rapid developnent i n t h i s area i n new c l i n i c a l l y a c t i v e drugs, i n new and improved laboratory t e s t methods, i n proposals of mechanisms of a c t i o n of A 1 agents, and i n t h e number of laboratory publications and patents disclosing new agents. A recent revie$ covers background material. The b e s t introduction t o current thinking i s found i n t h e published Milan Symposium on Nons t e r o i d a l A 1 Drugs3 and a chapter by Whitehouse4 on biochemical and pharmacological properties of A 1 drugs. There i s a need f o r improved antirheumatic agents. The s t a t u s of currently a v a i l a b l e agents i s i n dicated i n t h e theme of a recent A.M.A. panel discussion on t h e subject5: "Risk vs. Benefits i n Rheumatology," and i n other r e v i e w ~ . ~ , ~ Test Methods. Lnflammation i s a complex b i o l o g i c a l process .4 Attempts t o duplicate t h e c l i n i c a l s t a t e i n t h e laboratory have been l a r g e l y em, ~ a complex p i r i c a l . The r e s u l t i s a v a r i e t y of t e s t r n e t h o d ~ , ~and assortment of compounds claimed t o have A 1 a c t i v i t y . Order i s gradually appearing. With new c l i n i c a l l y a c t i v e agents a v a i l a b l e i n a d d i t i o n t o phenylbutazone (indomethacin, flufenamic a c i d ) , Winter% has reexamined various r a t p a w edema t e s t s . He concludes t h a t t h e widely used t e s t s employing formalin, egg white and serotonin a s p h l o g i s t i c agents a r e unsuitable ( i n s e n s i t i v e ) . He a l s o found t h a t s t e r i l e kaolin does not produce edema. These and other i r r i t a n t s (e.g., yeast and mustard) a r e known t o give p o s i t i v e r e s u l t s with antihistamines, antiserotonins and diverse o t h e r agents.='' The most r e l i a b l e t e s t s appear t o be t h e W erythema t e s t (W, guinea p i g ) , t h e antibradykinin t e s t (B, guinea pig bronchoconstriction), and t h e cotton p e l l e t granuloma t e s t i n t h e r a t (GC). A r a t paw edema t e s t using ~ a r r a g e e n i n ~ ~ ?(Ec) ~ ' , has ~ ~ been widely adopted. It i s a considerable improvement over older E t e s t s , although f a l s e "positive" r e s u l t s a r e obtained with high doses of a One a l s o finds frequent reference t o t h e v a r i e t y of medicinal agents." granuloma pouch assay ( G ) and a new and i n t e r e s t i n g t e s t system, an The l a t t e r t e s t , or ones adjuvant-induced a r t h r i t i s i n r a t s (A)53j54. l i k e it, o f f e r hope for finding drugs which w i l l provide preventive o r curative r a t h e r than symptomatic treatment of inflammatory diseases. Steroids a r e i n a c t i v e i n t h e UV and B t e s t s , but a c t i v e i n t h e GI GC, E and A t e s t s .

Chap. 20

Antiinflammato r y

Scherr e r

In t h e discussion which follows, a code system w i l l be used t o i n d i c a t e approximate a c t i v i t i e s r e l a t i v e t o phenylbutazone (PB), and t h e test method used. Thus 2 Ec i n d i c a t e s a compound i s about twice a s a c t i v e a s PB by t h e r a t p a w edema t e s t using carrageenin. (Other abbreviat i o n s : y=yeast, d=dextran.) In a d d i t i o n t o t h e above tests most A I agents a r e a c t i v e i n antinociceptive tests involving inflamed t i s sues3h,13>14 and i n various writhing rodent t e s t s (presumptive of analg e t i c a c t i v i t y ) , o f t e n i n proportion t o t h e i r A1 a c t i v i t y . They a r e a l s o a n t i p y r e t i c . These agents a r e commonly r e f e r r e d t o a s antiinflammatory a n a l g e t i c s or a n t i p h l o g i s t i c agents t o d i s t i n g u i s h them from s t r i c t l y c e n t r a l a n a l g e t i c s . A number of non-steroidal antirheumatic agents appear t o a c t by a d i f f e r e n t mechanism from t h e a n t i p h l o g i s t i c antimalarial^,^ p r o t e o l y t i c agents. These include gold preparations enzyme^,"^ and agents s p e c i f i c f o r gout.' These will not be covered i n t h i s review. Receptor S i t e . In 1964 t h e Parke-Cavis group15 proposed a hypothetical presented a receptor t o accommodate a number of known A1 agents; s i m i l a r receptor based on an a n a l y s i s of t h e indomethacin s t r u c t u r e and s u b s t i t u t i o n e f f e c t s . 'Phe main f e a t u r e s , outlined i n f i g . 1, a r e a l a r g e f l a t area, a trough t o accommodate an out-of-plane group (such a s an a r y l r i n g ) , and a c a t i o n i c s i t e t o accommodate an a c i d anion (or unprotonated amine?). It will be seen t h a t a number of agents described below can be f i t t e d t o t h i s receptor. The c o r r e l a t i o n i s probably higher among known W-active compounds. These agents w i l l be discussed by broad chemical c l a s s i f i c a t i o n s .

@ cationic

site

c1 fig. 1

I

Arglacetic Acids. !Phis c l a s s probably represents t h e area of g r e a t e s t research e f f o r t i n t h e A 1 f i e l d today. One of t h e most s i g n i f i c a n t events i n medicinal chemistry i n 1965 was t h e NDA approval and marketing of indomethacin (I, & r c k j 2 Ec, 85 GC, 3 W, 4. B, 25 A * potency i n man i s several-fold W ) . The chemistry,3b and c l i n i c a l review^^'^ a r e available.

225 -

226 -

Sect. I V

-


Heinzelman,

C l i n i c a l r e p o r t s have appeared17 i n d i c a t i n g t h a t t h e diethylaminoethanol s a l t of a-ethylbiphenylylacetic a c i d (namoxyrate, Warner-Lambert ) is an e f f e c t i v e A 1 agent and a n a l g e t i c . Superiority of t h e s a l t over t h e f r e e acid (mouse writhing t e s t ) i s t h e b a s i s of a patent claim." Boots Pure Drug has received a patent on a s e r i e s o f bipheqlyl- and a-methylbipheqly l a c e t i c a c i d s ( s u b s t i t u t e d on Ar), but omitting a-methylbiphenylylacetic a c i d i t s e l f .19 The l a t t e r , along with numerous carboxyl derivatives i s now covered by a Merck patent.20 Patents on 4- and 5-phenyl-1-naphthaleneacetic acids, and &-substituted and a-alkylated derivatives have appeared.21 All t h e above a r e claimed t o be A1 agents.

,

4-Isobutylphenylacetic acid (ibufenac, Boots Pure Drug; 0.2-0.4 W ) has been found t o be c l i n i c a l l y a s e f f e c t i v e a s a s p i r i n , a t h a l f t h e dose, i n various rheumatic conditions, but hepatotoxicity may l i m i t i t s usefulness.22 An extensive Merck patent has now appeared covering hundreds of Ar-substituted 4-alkyl- and 4-cycloalkylphenylacetic a c i d s a s A 1 agents. 23 The e f f e c t of a - s u b s t i t u t i o n on t h e A 1 a c t i v i t y of various a r y l a c e t i c acids was t h e subject of two recent publication^.^^'^^ Substituted 1naphthaleneacetic acids were superior t o t h e corresponding phenylacetic acids. The best compounds i n t h e 1-naphthalene s e r i e s (e.g. a-furfuryl, 0.25 W ) were not much more a c t i v e than t h e unsubstituted acid (0.12 W) Buu-Hoi26 f i n d s A1 a c t i v i t y i n pn-butoxyphenylacethydroxamic a c i d ( *HBCH(CN)~ Br

p r e p a r a t i o n of a , a - d i c h l o r o ketones involves the r e a c t i o n of a c e t y l e n e s w i t h N-chlorosuccinimide i n methanol t o . g i v e t h e dihalodimethyl k e t a l s which a r e r e a d i l y hydrolyzed w i t h d i l u t e a c i d s t o t h e ketones.30 The r e a c t i o n i s of g e n e r a l use and a f f o r d s t h e ketones i n y i e l d s of 60-8N. Enol a c e t a t e s derived from aldehydes having two a-hydrogens r e a c t w i t h b i s ( 1,2-dimethylpropyl)borane. The i n i t i a l addit i o n involves a s l o w "anti-Markovnikov" hydroboration b u t a r a p i d e l i m i n a t i o n and rehydroboration occurs.31 Enol a c e t a t e s derived ketones do n o t g e n e r a l l y r e a c t .

Sect. VI

318 -

-

Topics in Chemistry

S m i s s m a n , Ed.

Hydroxylamine-0-sulfonic acid will aminate olefinic, acetylenic, and aromatic compounds.32

@CH'=CH2

+

H2NOSOaH

pp;

>?FeC1 CH3OH FeS04

>

@ -CH2 oay, NH2

New uses of eneamines have been reported. A new heterocyclic synthesis involving an enamine cycloaddition with Ncarbethoxyaziridine and 1-pyrrolidinocyclohexene produced a 42% yield of IV.33 Dichlorocarbene forms an adduct with the piperdine

0

IVCooCaH5

eneamine of cyclopentanone which undergoes ring expansion to 2-chloro-2-cyclohexene-l-one.34 Ring expansion from the corresponding cyclohexanone adducts was not obtained. Benzene diazoniumchloride was found to react with l-piperidinocyclohexene. 35

n

0

a-Formyl ketones can be prepared from enamines by Vilsmeir formylation. Phosgene, dimethyl formamide, and l-morpholinocycloalkenes yielded the a-formylketones on hydr~lysis.~' Phosphorous acid tris(dimethylamide), [ ( M ~ Z N ) ~ P ] is , suitable in many cases in lieu of triphenylphosphine for the Wittig rea~tion."~ The increased rate of formation of the phosphonium salts and the water solubility of the resulting ( M ~ z N ) ~ P O formed along with the olefins simplified the preparation of the olefins. "he Wittig reaction is used in a new synthesis of a-branched-B-keto esters.38 The product of the Wittig is C1

+

Ph3P

p

COzEt)R' * PPhsIC1 C-COzEt o-200 3 [I&( I c 6H6 R'

Chap. 29

Chemical Reactions

319 -

Smi s s m a n

electrolyzed to give good yields of the corresponding ester. Other yields have found wide synthetic use. Dimethyloxosulfonium methylide and dimethylsulfonium methylide are both nucleophiles and both function to transfer methylene to certain electrophilic unsatur ed linkages including C=O, C=N, C=S, and in certain cases C=CO3$ A new synthetic route to ketones and "overall methylene insertion" are examples of the use of this system. Carbamyl-stabilized sulfur yields have been prepared via treatment of the corresponding sulfonium salts with sodium hydride. These yields react with Schiff bases to produce 3aryl amino cinnamate der atives to demonstrate the synthetic potential of the series.

48

A new synthesis in good yields of amino alcohols with tertiary alcohol groups involves a selective Grignard reaction.41

The reaction of vinyl Grignard reagents with a-unsaturated esters gives a preparative method for a,y'-unsaturated ketones.42 0

RCH=CHMgCl +

It

RYHCHCCH = YCH3 Ch2=CH R

CH CH C = CHC02Et 3 31

R

Triethylaluminum reacts with benzonitrile. 43 The reaction is believed to proceed through a 6-ring complex utilizing one of the 0

ethyl groups from triethylaluminum for ring formation. a,a'-Dibrominated dicarboxylic acids can be prepared by bromination in formic acid solution in the pr sence of red phosphorous and irradiation with a 200 watt kmp.t4 The yields are excellent. A convenient synthesis of cycloalk-2-eneones and a,P,a',P'-cycloalkadienones utilizes the direct bromination of 45 several cycloalkanones in ether followed by dehydrobromination.

'

Other interesting substitution reactions have been reported durin.g the year. N-formyloxyme 1-N-methylformamide proves to be a useful electrophilic reagent. The acid catalyzed reactions of this compound with carboxylic acids, alcohols, a mercaptan, 9-naphthol, anisol, phenol, and thiourea have been studied. All the reaction involve the carbonium ion,@ CH NMeCHO = as an intermediate, The phenolic hydroxyl doup will nucleophilic replacement by the mercapto group in acid solution. The following mechanism was proposed.

3 20

Sect. VI

-

Topics in Chemistry


7 RS

A simple s y n t h e s i s of p-hydroxy-a-amino m o d i f i c a t i o n of t h e S t r e c k e r r e a c t i o n . 4 8 CH2=CH-OAc

-&+

CH2CH( O A c )

I

OAc

1.NH40H KCN/ 2. HC1

>

a c i d s involves a 1:2-E2C00H

S e r i n e can be converted i n t o a p y r a z o l i n e b y a novel s e r i e s of I f t h e p y r a z o l i n e i s heated, cyclopropane reactions.*' COOH

2,4,6

(Me02C)3CeH2F = DL-Serine

NaHC03

> f"2-c\I

CH2Np

NH

CO 2 M e

&Me

d e r i v a t i v e s a r e obtained. Threonine a f f o r d e d s i m i l a r r e s u l t s . A new method was developed f o r t h e s y n t h e s i s of cyclopropane d e r i v a t i v e s by t r e a t i n g phosphonenolpyruvic a c i d t r i e t h y l e s t e r [ ( E t O ) 2P( 0) CH( :CH2) C 0 2 E t 3 (V) w i t h compounds c o n t a i n i n g a c t i v e methylene groups.50

VI, was reR-H, R'=NH2, n=O gave an active analgetic.

A new sgyies of 1-aminomethylbenzocyclobutenes,

ported,

Chap. 29

Chemical Reactions

Smi s s m a n

321 -

Tryptophan can be s e l e c t i v e l y a l k y l a t e d a t t h e indole-N p o s i t i o n w i t h sodium i n l i q u i d ammonia and v a r i o u s a l k y l h a l i d e s . 5 2 E t h y l a c e t o a c e t a t e can be benzoylated by using E t h y l b e n z o a c e t a t e i s obtained i n 45s aluminum c h l o r i d e . y i e l d . A method is described f o r t h e cleavage of benzyl ethers i n molecules c o n t a i n i n g m u l t i p l e bonds u t i l i z i n g sodium and butanol. 8-Phenoxyacrolein w i l l condense w i t h sodio d e r i v a t i v e s of a c t i v e methylene compounds.55 The l a t t e r compound w i l l undergo

’’

’‘

OCH=CHCHO

+

NaCH ( C 0 2 E t ) 2

---+

( E t 0 2 C ) 2CHCH=CHCHO

v a r i o u s r e a c t i o n s such a s a l k y l a t i o n and eneamine formation.

322 -

1. 2.

3. 4.

5. 6. 7. 8. 9. 10. 11. 12.

130 14.

15. 16.

17.

18. 19.

20.

21.

22.

23.

24.

25. 26.

27 28.

Sect. VI 0. House,

H.

-


Topics in Chemistry

"Modern S y n t h e t i c Reactions" W. A. Benjamin,

I n c . , N. Y., 1965. E. F r a n k e l , E.

and R. B u t t e r F r a n k e l , E. Emkeq

f i e l d , 2. Org. and V. Davison, F. H. J a r d i n e , Chem. Ind. 560 ( 1965). E. E. Van Tamelen, M. Davis, and M.

and J. F.Young,

--

71 (1965).

Vincent, Jr., and R.

H. Feuer, F. B.

Chem., 2,2877 (1965). W. E. Truce and F. M. Perry, E. H.

L. C.

3.

Deem, Chem. Commun.

F. S.

Bartlett, J. Org.

Org.

E l i e l and D. N a s i p u r i , 2. Org. Brown and P. M. Weissman, 2.

5614 (1965).

W. Hoefling, D. E i l h a u e r , and G. Reckling, G e r .

:!2iega%, Y. Yamada,

S.

9

Chem. Ind. 1496 ( 1965). K. Kagawa, and S. Ikegami, Chem. Pharm. B u l l .

394 (1965).

G.

R.

( 1965) *

36,

(East)

, 18047.

Bacon and W.

J. W.

Hanna,

2.

Chem. S o c . ,

4962

P. Kolsoker and 0. Meth-Cohn, Chem. Commun., 423 (1965). B. Acott and A. L. J. B e c k w i t h m e m . Commun., 161 (1965). B. Acott. A. L. J. Beckwith. A. H a s s a n a l i and J. W. Rednrxld. Tetrahedkon Letters 4039 (1965). K. E. P f i t z n e r and J. G. Moffatt, 2. &I. Chem. SOC. 5670 (1965). T. Suga, K. Kihara, and T. Matsura, B u l l . Chem. SOC. Japan

-

,

8, 1 1 4 1 (1965). & B h a t i , Chem. Commun., K. N. Parameswaran and

476 (1965).

a,

g.

Chem. 988 (1965). Van E s , J. Chem. SOC., 1564 (1965). J. K. Kochi; g x C h e m . Soc., 2500 (1965). D. H. Barton, H. P. Faro, E. P. erebryakov, and N. F. Woolsey, J. Chem. SOC., 2438 (1965). B. Fontal-and H. Goldwhite, Chem. Commun., 111 (1965). K. A. Oglobolin and V. P. Semenov, G. Organ. Khim., 27 (1965); c~:62, 16009. K. A. o g l o b x n and A. A. Potekhin, G. Organ. Khim., &, 0. M. Friedman,

T.

8,

2,

865 (1965); g : 6

, 6873.

$

98

P. Gruenanger , F i n z i , and C. S c o t t i , Chem. B e r . , 623 (1965). Y. I. Smushkevich, V. N. Belov, B. V. Kleev, and A. Y. Akimova, G. Organ. Khim., 1, 288 (1965); CA:62, 16073. K. Torssell and E. Ruusa, A % i v V9"f1965); 2:

B, 3,

T o r s s e l l and R.

, 6839. F.

Reed, Jr.,

2.

Ryhake,

Arkiv

Org. Chem.

e, 2, 537

, 2,2195

(1965); CA

(1965).

Chap. 29

31. 32.

33.

34. 35.

36. 37. 38. 39 40.

41.

42.

43.

323 -

Smi s s m a n

Chemical Reactions

B. D. B i g l e y and D. W. Payling, 2. Chem. Soc., 3974 (1965). F. M i n i s c i and R. G a l l i , Tetrahedron L e t t e r s , 1679 (1965).

J.

E.

D o l f i n i and J. D.

4381 (1965).

Simpson,

2. &I.

Chem. SOC.,

3,

- g.,

720 (1965). J. Wolinski, D. Chan, and R. Novak, Chem. V. I. Shevedov, L. B. Altukhova, and A. N. Grinev, g.Orga

K h i m . , 1, 879 (1965); =:2, 6893. W. Ziegznbein, Angew. Chem., , 380 ( 1965). H. Oediger and K. E i t e r , Ann.qhem , 682, 58 H. J. Bestmann, G. 620 (1965). E. J.. Corey and M.

(1965);

J.

Graf, H.

e: 9 , 1353 (1965).

A. Speziale, Chem. s. S a m e and!&: C. Lunibroso and ( 1965).

- %.,

( 1965) *

Hartung, E e w . Chem.,

Chaykovsky, J .

&I.

Chem. SOC.,

3,1,345 -

C. C. Tung K. W. R a t t s , and A. Yao, J. Am. 3460 (1965j. Rigny! Compt. Rend. 260, 1678 (1965). P. Maitte, B u l l . S o c T h i m . France 31-5

Nauk

44.

45. 46. 47.

48. 49. 50.

51. 52.

Org. ( 1965). . _ . H. Geipel, J. Gloede

, 1381

‘1

g, 1677 (1965j.

E.,

K.

P. H i l g e t a g , and H.

Gross, Chem.

F. M i c a e l , 0. Eickenscheidt, and I. Z e i d l e r , Chem. -*, Ber 3520

(1965).

, 216

(196).

son, J .

( 1965) *

e.-,

8,

255

54

S. Yamada, T. S h i o i r i , T. Haya, T. Hara, and R. Matsueda, Chem. Pharm. B u l l . , 88 (1965). K. Matsui and T. N o j i r i , Kagaku Azsshi, 86, 531 (1965); 8242. F ’ g ’ M a r k i e w i t z and C. R. Dawson, 2. Org. Chem., 30, 1610

55.

R. G e l i n and D.

53.

2:

-

( 1965)

-

Makula, COmPt.

Rend.

& I , 489

(1965).

3 24 -

Sect. VI a a P * 30

-

Topics in Chemistry


ANTIRADIATION AGENTS William 0. Foye

Department of Chemistry Massachusetts College of Pharmacy Boston, Massachusetts The medicinal chemistry of antiradiation agents is concerned here primarily with the development of new radioprotective agents and their activity. Such a discussion necessarily omits much of the work in radiation biochemistry and contiguous areas, although interesting new developments where chemical interactions have been shown to take place are included. The subJect of ohemical radioprotection and radiosensitization of tumor-bearing systems has been touched only briefly, covering events subsequent to the reviews cited, and is really worthy of a separate review. Methods of biological radioprotection and clinical aspects have not been covered in this report. Preparations of potentially active antiradiation agents without report of protective activities regretfully have been left for future reviewers when radioprotective results may have become known.

-

Reviews. New books concerning chemical radioprotectionl and t m n c i p l e s of radiation protection2 have appeared. Current concepts of chemical protection against IonizrLng radiation have been re~iewed,~" and the role of copper and peroxides in radiobiology has been discussedOs The 92 papers presented at the First International Symposium on Radiosensitizers and Radioprotective Dmgs in 1964 have appeared in a well-organized volume.6 The use and pharmacology of radioprotective aminothiols, disulfides, nitriles, and other compounds has been r e v i e ~ e d . ~ Radioprotective Compounds 2 Mammals.- Chemical modification of the MEA and MBQ structures has continued actively, although no real improvement over these two basic structures has-been re: ported in the past two years. A new direction f o r syntheses of potential radiation protectors appears to be among heterocyclic systems, where protective activity is being found apart from any sulfur content of the molecules. Several non-basic thiols have also been reported active, and sulfur-containing analogs of the amino acids have shown some radioprotective effects. Protection by metal chelating agents, metal chelates, and metal ions themselves has pointed to the importance of the role of metal Ions in cellular radiation effects. Heterocycles. Among a group of 22 thiazolines tested in mice vs. 850r (V-radiation), "aminoethylthiazoline" provided up to 30rprotection, presumably because of its ability to hydrolyze to protective fragments in v i v ~ . Of ~ 15 imldazoles and related N-heterocycles, benzimidazole gave rats 90% protection 2. a lethal dose of x-raysOg In a subsequent series of imldazoles and benzimidazoles, ~~naphthylmethyl-2-imidazoleprovided 100% protection to mice.

Chap. 30

Antiradiation

Foye

325 -

3,5-Dlmethyl-l-( dlmethylcarbamoy1)-pyrazole was found to give 50s protection to mice E. x-rays (LDloo).lf Several C-alwlated thiazolines protected mice against a lethal dose of x-rays, and the activity was comparable to that from the mercaptoamlnes obtained on hydrolysis of the thiazolinea.12 A copolymer consisting of S-vinyl(2,2-dimethylthiazolidyl)-N-monothiolcarbamate and N-vivlpyrrolidone was also found effective E. x-rays in mice.13

Two 5,7-dihydroxyisoflavones, representing a class of compounds for which radioprotective ability has been controversial, were shown to afford 100% protection to mice 7OOr when administered percutaneously but were not protective by the intraperitoneal route l4

E.

.

Thiols. -Acetamldinlum thiosulfates, RNHC( =NH2+) CH2SS03-, were radioprotect1ve1%o mice 2. a lethal dose of x-rays, and a substituted 2-amlnothiosulfiric acid, prepared froma-amlnobutyric acid, also gave good protection.16 The thiosulfonate of NH~CH~CH~SOZSCHPCH~NH~, afforded good protection to mice, and it also protected 2. marcescens at pH 7, where it is decomposed to cystamlne and hypotaurine, but not at pH 4, where it is stable.18 The aminothio acids derived fromdC-and/J-alanine and gigcine showed Good prono protective activity in rodents but did in bacteria. tection in mice was provided by the@-aminoethylamlde,of thioglycollic acid, HSCHaCONHCH2CHzNHa, as well afsby N,N -bis(mercaptoN-Acetylthioacetyl)hydrazine, however, s.800r (x-rays) glycollic hydrazide, HSCH2CONHNHCOCH3, and its disulfide increased the LDSO of x-radiation in mice.20

T#,

.

The mixed disulfide of MEA and o-mercaptobenzoic acid was protective in mice z. a lethal dose of x-rays; this compound showed remarkable structural specificity, neither the meta or para isomers nor a variety of other close relatives were protectivem21 Thiols lacking a basic function also appeared with radioprotective activity. 2,3-Dithiosuccinic acid (both meso and dl 1-Phenyl-1forms) protected 90% of mice 7OOr (x-rays).22 acetthio-2-nitroethane, and its next higher homolog, showed some activity in mice VS. an LDloo dose of x-rays, whereas the corresponding amlnothix, 2-mercapto-2-phenethylamlne, was

E.

Numerous other interesting amlnothiol derivatives were synthesized without report of activities. ~lOC-Diallcyl-~-amlnothiols, and addition of long chain however, were found inactive in mice, N-alkyl groups to AET and the trithiocarbonate of MJ3G, RMIC(=NH2+) CH2CH2SC(=S) S-, also resulted in loss of a~tivity.~” Other Compounds. Hexacoordinated chlorophyllin-metal chelatea= with Co,M&,Mn,V) have been claimed to be radioprotective in mice; and a series of 1,5-diphenylthiocarbohydrazides capable o f metal ion chelation provided 40-65s protection to rats 750rm27 An a w n analog, ~-2,4,5-trichlorophenoxyethanol,

E.

326

Sect. VI

-

Topics in Chemistry


E.

which reduces normal oxygen consumption, protected mice 800r (V-radiation).28 The proestrogen, chlorotrianisene (tri-p-anisylchloroethylene), has shown the surprising property of protecting 80% of mice(vs. 590-690r) when administered 5-30 days prior to x-irradiati o E 2*

E.

Pyromellitic and benzenepentacarboxylic acids, but not 102% when administered mellitic acid, were protective in mice in high doses.30 It was considered that the activity resided In the osmotic effect of these polyionic substances which could cause hypoxia, rather than in the chelation of calcium ions known to occur. 750r, were believed to Gallate esters, which protected rats inhibit chain oxidation

E.

E.

Radioprotection of Other Systems.- Glycine exerted a protective Soor, but showed little effect effect on the catalases in mice on ATPase, pyrophosphatase, or gl~taminase.~~ Selenomethionine and selenocystine showed a greater protective effect for amino acids, yeast alcohol dehydrogenase, and RNase than the analogous sulfur cornpo~nds.~~ The r@ioprotective effect of both glycerolg4 and dimethyl sulfoxide for catalase was attributed to complex formation with the of catalase. Protection of catalase by a++, pe*, and ~n ions, however, was explained by radical scavenging.36

irs

Iron and copper ions also inoreased radioresistance of ceruloplasmin and hemoglobin, and a similar effect was shown by Nipicolinic acid and Ni-glycine chelates.s7 Other chelates did not protect these proteins. A correlation between radioprotection of proteins b inorganic ions and hydration energy of the ions was discerned, Incorporation of iron in erythrocytes was not inhibited by radiation (75r in mice) in presence of MEA, histamine, or serotonin,g9 Ehrlich ascites cells in mice VS. 400r (V-rays) were protected by eitheroC- or 0-alanine followed by arginine.40 AET protected both cancerous and healthy cells in mice from x-rays, but did increase the survival rate of cancerous mice.41 The gastrointestinal tract of rats was protected by perfusion with MEG gOCr, but Dunning leukemia cells were not eradicatede4= The hematopoietic 5OOr system of mice was protected by cysteine thiosulfonate (x-rays), but Crocker sarcoma cells also received protection. 43 The subject of chemical radioprotection and tumors has been recently reviewed. 44

E. E.

Radiosensitizers.- A review has appeared on studies of radiosensitizers in radlothera y of tumors.45 Radiosensitization of Ehrlich carcinoma cells by -methyluracil and 5-hydroxymethyl-4methyluracil has been O b S e r ~ e d ,as ~ ~well as by propyl gallate and other antioxidant^.^^ Mice proved to be radiosensitive to bdeoxypyridoxine, INH, Dbtryptophan, and Dbkynurenine E. 590r; taurine afforded some protecti~n.~~ Dogs were found radiosensitive to quinoxalinedi-N-oxide, whereas mice had been protected by this compound.4s Colcemide and urethane increased radiosensitivity in

t

Chap. 30

Anti r a dia tion

Foy e

327 -

mice when administered twelve hours prigr, but protected when given 48 hours prior to x-irradiation. Erythrocytes were sensitized by iodoacetic acid and related alelating agents ncluding ethyl methanesulfonate, iodine, and N-ethylmaleimide.5f E, coli cells have shown radiosensitivity to $,8 -dichlorodietGl =one, whereas the monosulfoxide of cystamine was only slightly sensitizing, and ions gave some protection.s2 Folic acid analogs53 and spar~omycin~~ sensitized -E. -coli to ionizing radiation, and Cu* ions sensitized 2. flexneri under anaerobic but not aerobic condition~.~~

-

Modes of Radioprotection.- The various mechanisms proposed for chemicarradioprotection have been recently evaluated by Bacq: A convincing argument in favor of anoxia was made for the radioprotective action of histamine, acetylcholine, and the catecholmines, but it was believed that the thiols and disulfides protect by interactions with free radicals and oxygen. Arguments in favor of radical interaction, and transfer of energy to sulfur, in combination with mixed disulfide formation, have been advanced recently in regard to protection by thiols.56 None of the complexities of this problem of explaining radioprotection have been removed by recent results, but it appears pertinent nevertheless to cite evidence supporting some of the current concepts.

No correlation between hypothermia and radioprotection by

MEA, cysteine, cyanide, 5-hydroxytryptamlne, or diethyldithio-

carbamate has been reported from two l a b o r a t o r i e ~ ;both ~~~~~ groups conclude that the interaction of MEA, at least, with free radicals constitutes its major protective role. A direct relation between radical inhibitory action and radiation protection was observed for antioxidant phenols, pyridines, and gallic acid esters.5s A correlation between vasoconstrictive effect and radioprotection was reported for the indole aminesO6*

It has been postulated that the introduction of thiols or disulfides into cells upsets the thiol-disulfide equilibria present, resulting in the increased formation of free thiol groups which can react with radicalti Instantaneous repair of damage by H transfer then takes place. Some evidence for this idea has since been reported. Increased amounts of an endogenous compound with reactive thiol groups has been observed after MEA treatment,62 as well as an increase in the thiol level of spleen,63 and the The latter compound could release of intracellular gl~tathione.~~ eliminate H a 0 2 via the glutathione peroxidase pathwayO6' The complexation of enzymes by protective agents has been proposed, and evidence for the existence of a protective glyceroliron-catalase complex has been advanced.6s Spectrophotometric evidence for the existence of complexation between catalase and MEA, MEG, and diethyldithiocarbamate has been observed, and the subject of metalloenzyme complexation discussed.66 Radioprotection of lactatedehydrogenase by complex formation with D-lactate has been and decreased catalase inactivation in the presence of owgen has been attributed to formation of catalase-peroxide complexes. 88

3 28 -

Sect. VI

-

Topics in Chemistry


The problem of energy t r a n s f e r , from radiation-induced r a d i c a l s t o e i t h e r v i t a l o r p r o t e c t i v e molecules, l i e s a t t h e h e a r t of t h e molecular events t a k i n g p l a c e i n t h e course of r a d i a t i o n p r o t e c t i o n . Any of t h e c u r r e n t hypotheses of r a d i o p r o t e c t i o n must u l t i m a t e l y consider t h i s e f f e c t . However, some understanding of t h e process is emerging5s*e5*eB-71 mainly by use of e.s.r. spectroscopy. References

.

(1) Bacq, Z.M., "Chemical P r o t e c t i o n Against I o n i z i n g Radiation," Charles C Zhomas, S p r i n g f i e l d , Ill., 1965. (2) Eaves, G . , P r i n c i p l e s of Radiation P r o t e c t i o n , " I l i f f e Books, London, 1964. (3) Baraboy, V.A., "Current Concepts of Mechanisms $f t h e P r o t e c t i v e Effect of Chemical Compounds Against Radiation, Office Tech. 1964. Serv., J.P.R.S. Report 26,842, Washington, D.C. 4 Langendorff, HiI, Arzniemittel Forsch., 463 (1965). Copper and Peroxides i n Radiobiology and 151 Schubert , Medicine, Charles C. Thomas, S p r i n g f i e l d , Ill., 1964. (6) P a o l e t t i , R. and Vertua, R . , "Progress in Biochemical Pharmacology," Vol. 1, S. U r g e r A.G., B a s e l , and Butterworths, Washington, D.C., 1965. Shapiro, B . , Med. Clln. N. Am., 48, 547 Shashkov, V.S., & Radiobiologiya , R i n a l d i , R. and Bernard, Y., R i n a l d i , R., Bernard, Y., and

u,

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(1965)

(11) b o x , J . M . , Freeman R.G., and T r o l l , D., A c t a Radiol., Therapy, Phys. B i o l . , 2, 66 11965) (12) Handrick, G.R., Atkinson, E.R., Granchelli, F.E., and Bruni, R.J., J . Med. Chem., 8, 762 (1965). (13) Overberger, C.G., Ringsdorf, H., and Avchen, B., U ., 8, 862

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(1965) (14) Gazave, J . M . ,

Modigliani, D.C., and Ligny, G., Progr. Biochem. Pharmacol. Vol. 1, S. Karger A.G., Basel, 1965, P. 554. , 766 (1964). Bauer, L. and Sandberg, K . R . , J. Med. Chem., Gershon, H., and Rodin, R., U d . , 8, 864 (19 5 ) . F i e l d , L. F e r r e t t i , A., Crenshaw, R.R., and Owen, T.C., ibid.,

5

1,39 (1964). (18) Owen, T.C., Parker, M.S., and S t e r n , G.M., J . Pharm. Pharmacol., 108 (1965). (19) Atkinson, E.R., Handrick, G.R., Bruni, R.J., and G r a n c h e l l i , F.E., J. Med. Chem. 8, 29 (1965). (20) Rose, F.L. and Walpole, A.L., Pro r. Biochem. Pharmacol., Val. 1, S. Karger A.G., Basel, 19 5, P. 432. Crenshaw, R.R., and F i e l d , L., J . Org. Chem., 30, 175 (1965). Cugurra, F., and B a l e s t r i , E., Progr. Biochem. Pharmacol., v o i . 1, S. Karger A.G., Basel, 1965, P. 507.

z,

%

Chap. 30

Antiradiation

329 -

Foye

B h a t , K.V., and Mecarthy, W.C., J . Pharm. S c i . , 51, 1545 (1964). Stacy, G.W. Barnett, B.B., and Strong, P.L., J. Org. Chem., 311, 592 (1965) (25) Foye, W.O., Laiala, E.F. Georgiadis, M., and Meyer, W.L., J. Pharm. S c i . , 557 11965) 26 Kasugai, N., J. Pharm. SOC. J a b n , 84, 1152 (1964). (271 G o r d e t s k i i , A.A., e t a l . , Pato enez, Eksperim. P r o f i l a k t i k e i Porazhenii ~MOSCOW) , 1964, 179; Chem. Abstrs.,

s,

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S t e e r s , C.W.,

and Norman, D.,

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Nature, 205, 816 (1965). A.A., Baraboi, V.A,, and C h e r n e t s k i i , V.P. , Vopr. Biofiz. i Mekhanizma D e i s t v i y a I o n i z i r . R a d i a t s i i , 1964, 159; Chem. Abstrs., 18617 (1965). (32) Capalna, S., Ghizari, E., S t e f a n , M., and Petec, G. , S t u d i i Cercetari F i z i o l . , 2, 369 (1964) ; Chem. Abstrs. , 62, 13488 (1965) Shimazu, F. and Tappel, A.L., Radiation Reg. , 310 (1964) Lohmann, W., MOSS., A.J., Perkins, W.H., and Fowler, C*F., Biophysik, 2, 16 (1964). (35) Lohmann W,, Moss, A.J., a n d ' p e r k i n s , W.H., J . Nucl. Med., 6 519 (1965) (36) Lo-m, W. Moss, A . J . , and Perkins, W.H., Radiation R e s . , 24, 9 (19655. (37) Krsmanovic-Simic, D. and Duchesne, J. , Compt Rend. , 260

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Leonare, A . , and Hugon, J., J. Belge Radiol.,

a, 511 (1964).

(42) &&ms, J .L., Ambrus, C.M. , Pickren, J e w . t Felt23 E-, and Back, N., Cancer R e s . , E , 609 (1965) (43) Zebro, T., Stachura, J., Prochnicka, B. , and Syczepkowski, T. , Acta Med. Polona, 6, 155, 171 (1965). (44) Greco, S . , Gasso, G., and B i l l i t t e r i , A., Progr. Biochem. pharmacol., Voi. 1, S. Karger, A.G., Basel, 1965, P. 277. M i t c h e l l , J .So i b i d . , 335. Polsklna, R.I., Bychenkova, M., and Zalesskaya, L. , Acts unio 1219 (1964); Chem. Abstrs. 62, I n t e r n . Contra Cancrum, 9429 (1965) (47) Afanas'ev, G.G., Lipchina, L.P., and Pelevina, I.I., ibid., 1213 (1964) ; Chem. A b s t r s . , 62, 9428 (1965) (48) Melching, H.J. Abe, M., and S t r e f f e r , C., S t r a h l e n t h e r a p i e , 125,352 (19643 (49) m l e y , T.J., Trwnbull, W.E., and Cannon, J.A. , Progr. Biochem. pharmacoi., Voi. 1, S. Karger A.G., Basel, 1965, P o 359.

.

a,

a,

0

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3 30 -

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Topics in Chemistry

Rothe, W.E., Grenan, M.M., and Wilson, S.M., i b i d . , 372. Bianchi, M.R., Boccacci, M., Misiti-Donello, P., and Q u i n t i l i a n i , M., I n t e r n . J . Radiation Biol., 8, 329 (1964) 8, 519 (1964). S t u y v a e r t , J . and Bacq, Z.M., iu., P i t i l l o , R.F., Lucas, M., Blackwell, R.T., and Wooley, C., J. Bacteriol., 1548 (1965) 773 (1965) P i t i i i o , R.F., e,t a l . , Nature Cramp, W.A., i b i d . 7 2 0 6 , 636 P i h l , A . and E e r , T , , Progr. Biochem. Pharmacol., Vol. 1, S. Karger A.G., Basel, 1965, P. 85. Bacq, Z.M.,Beaumariage, M.L., and Liebecq-Hutter, s o , I n t e r n . J. Radiation B i o l . , 2, 175 (1965). Magdon, E., Nature, 204, 484 (1965) Burlakova, E.B., et Dokl. Akad. Nauk S.S.S.R. ,

.

a,

(57)


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z,

934 (1965).

(60) Zherebchenko, P.G.,

.

164,

e t a l . , Patogenez, Eksperim. P r o f i l a k t i k e i Porazhenii (Moscow), 1964, 193; Chem. Abstrs.,

Nature, 203, 162 (1964) M.M., Sokolova, O.M. , and Tarasenko, A.G., Dokl. Akad. Nauk S .S.S.R., 441 (1965) Jamieson, D., Nature, 207, 541 (1965). Revesz, L. and Modig, H., U d . , 207, 430 (1965). Lohmanrl,W., Progr. Biochem. Pharmacol., Vol. 1, S Karger A.G. Basel, 1965, p . 118. Foye, W.O., and Mickles, J . , i b i d . , 152. Dose, K., i b i d . , 161. Magdon, E., S t r a h l e n t h e r a p i e , 258 (1965). Alexander, P., L e t t , J.T., and Dean, C . J . , Progr. Biochem. Pharmacol., Voi. 1, S. Karger A.G., Basel, 1965, p . 22. Nicolau, C., Qrigorescu, S., and Nedelcu, C., i b i d . , 472. C a s t e l e i j n , G., Depireux, J., and Muller, A . , Intern. J . Radiation B i o l , 8, 157 (1964)

P.,

164,

126,

.

.

,

Chap. 31 PHARMACEUTICS AND BIOPRARMACEUTICS

Tgkeru Higuchi and Kenneth F. Finger School of Pharmacy, University of Wisconsin, Madison, Wisconsin W i l l i a m I. Higuchi School of Pharmacy, University of Michigan, Ann Arbor, Michigan The science of dosage forms and their influence on drug absorption and u t i l i z a t i o n is a r a p i d l y growing medicinal f i e l d . I n t h i s s h o r t review w e have attempted t o present a l i m i t e d b u t r e p r e s e n t a t i v e development i n t h i s area occurring within the p a s t two years. The materials treated, admittedly, are i n t h e areas of p a r t i c u l a r interest t o t h e reviewers. THERMODYNMIC AC’PIVITY,

SOLUBILITY AND COMPLEXING

Although thermodynamic p r o p e r t i e s of medicinal agentsin s o l u t i o n has received r e l a t i v e l y l i t t l e a t t e n t i o n i n the p a s t , there are a number of reasons why they should be of a major concern t o medicinal chemists. One can r e a d i l y show, f o r example, a direct r e l a t i o n s h i p between t h e physiological a c t i v i t i e s of drugs and their thermodynamic a c t i v i t i e s a t the s i t e of action. One should a l s o note t h a t t h e rates of drug t r a n s p o r t and absorption across membrane relate. more t o thermodynamic a c t i v i t y than t o concentration. Drug s o l u b i l i t i e s which are i n v e r s e l y proportional t o thermodynamic a c t i v i t y c o e f f i c i e n t control, of course, rates of d i s s o l u t i o n and a v a i l a b i l i t i e s of many drugs. And f o r p r a c t i c a l purposes it is more convenient and o f t e n necessary i n many instances t o administer parentera1 drugs i n s o l u t i o n thus r e q u i r i n g rather s o p h i s t i c a t e d understanding of s o l u t i o n chemistry t o permit d i s s o l u t i o n of less s o l u b l e pharmaceuticals. For these reasons t h e nature of t h e s t r u c t u r e s of s o l u t i o n s of drugs i n aqueous and nonaqueous s o l v e n t s and the mechanisms of a c t i v i t y of cosolvents i n these systems p a r t i c u l a r l y have been r e c e n t l y subjecQs of increased scrutiny. c o r r e l a t i o n of s o l u b i l i t y p r o p e r t i e s of nonaqueous systems t o a s i n g l e parameter such as dielectric constant has been attempted by s e v e r a l groups i n t h e l a s t two years w i t h l i m i t e d A t r y by Restaino and Martin t o f i t s o l u b i l i t y of benzoic acid i n various n-alkanols3 t o Hildebrande’s theory of s o l u t i o n proved t o be u n f r u i t f u l . I n these instances t h e s o l v e n t phase has been e s s e n t i a l l y assumed t o be a continuum. A more e f f e c t i v e recent a p p r o a ~ h ” ~ has been t o look a t solute-solvent-cosolventinteractions on a molecular basis, the t o t a l s o l u b i l i t y of c r y s t a l l i n e drug A i n solvent B and cosolvent C being represented by a summation

332 -

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VI

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S m i s s m a q , Ed.

Topics in Chemistry

P'" Total solubility =

knnp

A"B~CP

L

n = 1 m - 0

P * O At saturation the thermodynamic activity of each species present is equal to that of the solid solute. The total solubility behavior furthermore must take into account the interactions between B and C species. The mechanism responsible for increases in solubility induced in aqueous solutions by addition of cosolvent continues to be largely associated with formation of solute containing species in these systems. The species may take the form of simple one to one or one to two molecular complexes between the solubilizing agents and the solubilized solutes as reported recently for a series of or less stoichiometrically defined hydroxyaromatic acid giant aggregates such as micelles or adducts between dispersed polyether surfactants and low molecular weight phenols. ""lo' l2 A rather interesting instance of solubilization and complex which apparently formation was reported by Lach and coworkers'" involves trapping of organic solutes into cage-like structures of cyclodextrins or Schardinger dextrins in aqueous solutions. The observed stability constants are apparently quite high and the chemical behaviors of the bound species are significantly altered in several instances. There may be some relatipgship between these and starch adducts reported by Goudah and Guth.

''

'"

DRUG STABILITY

Increasing attention has been directed towards elucidation of mechanism responsible for deterioration of medicinal preparations. Since drug formulations often involve relatively complex mixtures of polyfunctional organic and inorganic species, chemistries of their breakdown on storage under varying conditions for periods of months and years can indeed be quite involved. Mechanisms of degradation of cycloheximidef6 of porfiro~~ycin:~ of hydroxocobalmin," of Mannich coopounds,lB of diaminotriazine derivatives,=' of apomorphine,'' of iodoxuridine,22 and of methicillin*' are representative of some of these systems recently studied. Attention should be called to series of papers on an anaerobic loss of ascorbic acid. 24

Chap. 31

Biopharmaceutic s

Higuchi, Finger and Higuchi

333 -

Steroids continue to receive attention. Although prednisolone in queous solution undergoes oxidative breakdown catalyzed by metals, s J p * Jensen and Lamb have shown that autoxidation of fluprednisolone acetate is preceded by a hydrolytic step. 27 Participation of other ingredients in formulations affecting drug stability has become increasingly evident. Citrate and tartrate buffers, for example, have been shown to be in slow equilibria with their corresponding acid anhydrides which can react rapidly with any nucleophile which may be present.20’2s’30 Waake and G ~ t t m a n ,on ~ ~the other hand, have found that formation of a borate complex tend to stabilize riboflavine. Lach in his studies on cyclodextrins have shown that these form complexes with drugs often conferring great atability to the bound guest. 32 PHARMACEUTICS OF HETEROGENEOUS SYSTEMS Powders, Su sions and Emulsions: Rippie and his collaborators some noteworthy stur3ies on the segregation have report8 kinetics of particulate solids. These investigators have taken steel and glass balls of various sizes loadzd into cylindrical containers and subjected them to vertical sine wave motion. Samples were taken at various times and standard deviations from the mean composition were determined. Segregation of binary m i x tures of spheres followed an apparent first order approach to equilibrium. Employing this technique the authors have studied the influence of particle size, size distribution, particle densitysize interactions, and the dependence of the agitation upon the segregation rate. Other variables such as particle shape could be studied also. While the idealized experiments have not included (and may not be able to include) some of the factors important in real systems, e.g., particle-particle adhesion, particle wall adbeeion, and electrostatic effetrts, they have quantitatively clarified many aspects of the particulate mixing phenomena and demonstrated the importance of this kind of approach. Shlanta and M i l o s o ~ i c hhave ~ ~ described an apparatus for studying stress relaxation of p e e r beds under constant strain. The technique appears to be useful for studying elastic compressifactors that are bility, relaxation and flow under pressure basic to the understanding of the tabletting process. The Coulter Counter played an important role in research on emulsions and suspnsions of pharmaceutical significance. Lemberger and Mourad 7338 studied the influence of a number of variables on the deaggregation behavior of oil-and-water emulsions. R ~ , s ealso employing the Coulter Counter, studied the effect of emulsifier type and concentration on the particle size distribution of oil-in-water emulsions. Edmundson and Lees4’ determined the dissolution rate of a fine suspension of hydrocortisone acetate in water using the Coulter Counter. These and other work41J42J4swith

-

3 34

Sect.

VI - Topics in Chemistry


this instrument involving emulsions and suspensions point out the value of this tool in future work with pharmaceutical dispersed systems Dissolution Rate Behavior: A number of studies on the rate of dissolution have been recently reported. Wurster and his a s s ~ c i a t e ~ ~ ~ ~studied ~ ~ ~ *the ~ heffect a ~ e of complex formation on the dissolution rate of drugs and the dissolution behavior of the three different crystalline forms of prednisolone. In the latter study these investigators observed the unusual effect of agitation on the relative dissolution rates of polymorphs first reported by Hamlin et al.47 Theaissolution rate behavior of polyphase systems has recently received the attention of several workers since the report by Sekiguchi and Obir8 that the eutectic mixture of sulfathiazole and urea gives a much higher drug release rate than the pure drug alone. The authors had attributed the greater rate to the c smaller crystals in the eutectic mixture. In their recent work with the chloramphenicol-urea system, Sekiguchi et al.4e found that the drug-urea mixture of 1:4 (W/W) dissolved significantly faster than the eutectic composition. The authors proposed that urea solubilization of the drug was probably the more important factor. Goldberg et. G.’’ has suggested the possibility of solid solution formation in these systems as an alternative explanation. Higuchi et. al. s’ have presented a mathematical analysis of dissolution rates involving polyphase mixtures which should be helpful in resolving the various factors.

.

-i-

BIOPHARMACEUTICS Current thinking in regard to the absor tion of drugs is based largely on the early studies of OvertonSg and Collander and Barlund” who have advanced the concept of the lipoidal nature of the biological membrane and more recently upon the work of Schanker, Brodie, Hogben and c 0 1 1 a b o r a t o r s ~ who ~ have ~ ~ ~defined ~ ~ ~ ~ the ~ ~ ~ ~ role of lipid/water partition coefficients, ionization and pH in the passive transport of drugs and other foreign compounds across biological membranes. !Chese studies have shown that most drugs are absorbed by passive transport and that the rate of absorption is a function of the concentration gradient of the diffusing moiety across the menibrane which in turn is dependent upon the lipid/water partition ratio of the diffusing moiety. The diffusing moiety for weak electrolytes is the non-ionized portion of the dissolved drug. Passive absorption of lipid-insoluble molecules occurs through small aqueous channels or pores in the membrane if the molecules possess sufficiently small molecular volumes to permit passage through the pores. The transport of highly icpnized, lipidinsoluble compounds, such as the quaternary amines, is not satisfactoily e lained by the above mentioned lipid-partition theory. LevinsB has postulated that the transport of quaternary amines

Chap. 31

Biopharmaceutic s


may Be dependent upon the interaction of these highly ionized molecules with a phosphatido-peptide constituent of the membrane and it is this complex that is the diffusing moiety in the transport of quaternary &nes across biological membranes. Such an interaction satisfactorily explains the rapid, but short lived oral absorption characteristics of the quaternary amines observed in man and other animals. The mechanism of permeation of biol ical membranes has * been the subject of several recent reviews. eo31 From the biopharmaceutical standpoint, the absorption of a drug into the body encompasses other parameters in addition to the permeation of the biological membrane. Included among these are dissolution properties (rate of dissolution and absolute solubility), drug interactions affecting drug availability and diffusion of the drug from its site of dissolution to the absorptive surface. These parameters will constitute the subject material to be discussed in the following paragraphs. Rate of Dissolution and Drug-Absorption: Both absolute solubility and the rate of solubility are important parameters in the overall absorption processes, It-has long been known that a compound must possess sufficient aqueous solubility to be effectively absorbed from the gastro-intestinal tract as well as other obsorptive sites, More recently, Nelson" has clearly elucidated the role of the rate of solubility in the absorption process and pointed out the theoretical relationships that exist between the rate of dissolutfon of a particle and its surface area, diffusion layer pH and the concentration gradient of drug across the diffusion layer. The rate of dissolution principles have provided the theoretical bases for many recent biopharmaceutical studies. The effect of particle size of sulfisoxazole on its oral absorption in dogs has been studied by Fincher, Adams and BeaLeS These authors concluded that the rate of absorption of sulfisoxazole was a &unction of the particle size of the crystals administered, faster and higher blood levels of the drug being obtained with the smaller crystal sizes. Their results indicate that while the rate of absorption was affected by particle size, there was no alteration in the total percentage of administered dose absorbed thus giving rise to the possibility that the blood levels of sulfisoxazole could be controlled by regulating the particle size of the administered drug. The rate determining step in the absorption of salicylate from pharmaceutical dosage forms appears to be the dissolution p r o c e ~ s ? ~More ' ~ recently, ~ ~ ~ ~ Truitt and Morganes have studied the absorption of buffered and non-buffered dosage forms of acetylsalicylic acid in humans and have related their in vivo findings to differences in dissolution rates of the administered aspirin. Their results indicate that (a) statistically significant differences in the rate of aspirin absorption from buffered and non-buffered tablets do exist and (b) the enhancing effects of bufferbmg are primarily upon the rate of dissolution of the acetylsalicyclic acid.

''

--

.

335 -

3 36 -

Sect. VI

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Topics in Chemistry


'Fhue, when the buffered a s p i r i n formulation w a s administered as a s l u r r y o r as a solution, buffering had no enhancing e f f e c t u p n the overall rate of absorption of a c e t y l s a l i c y l i c acid. Only when the tableted form of a s p i r i n w a s administered d i d the enhancing effect of buffering appear, suggesting that the r o l e of the buffer is t o a l t e r diffusion layer pH and thus increase the dissolution rate of the aspirin. The importance of dissolution rate on the rate of absorption of s a l i c y l a t e was a l s o shown bY Lieberman and Wood7' who found that higher blood s a l i c y l a t e levels and more rapid absorption of s a l i c y l a t e occurred when the analgesic w a s administered i n the form of a solution than when administered as either a buffered o r non-buffered tablet. Their data indicate t h a t buffering enhanced the overall absorption rate of a c e t y l s a l i c y l i c acid when administered i n tablet form. Levy and I i ~ l l i s t e r ~ were ~'~* a l s o able t o show a relationship between the rate of dissolution and the rate of absorption of a c e t y l s a l i c y l i c acid i n humans. These authors employed both

conventional compressed tablets and an experimental sustained release preparation employed produced a s i g n i f i c a n t l y reduced dissolution rate as compared t o the dissolution rate obtained f o r the compressed tablets. Similarly, the f i r s t order rate constants f o r absorption following the administration of the sustained release from were s i g n i f i c a n t l y lower than those obtained w i t h the compressed tablets. I n addition, the sustained release dosage form caused a delay i n the onset of absorption i n most patients. Despite the delay i n onset of absorption and the much slower rate of absorption, the t o t a l amount of s a l i c y l a t e absorbed f r o m the sustained release dosage from compared favorably w i t h that obtained from t h e conventional tablet. These r e s u l t s i n d i c a t e again the r o l e of the rate of dissolution i n the over-all absorption rate of acetyls a l i c y l i c acid. The importance of rate of dispersion and dissolution of a drug w a s made evident by the work of Calesnick, Katchen and Black7' who administered various dosage forms of diazoxide and obtained blood levels and biological response data i n humans. Comparing tablet and capsule forms w i t h an aqueous solution of the drug, these authors found the highest blood levels were obtained when the aqueous solution of diazoxide w a s administered, lowest blood levels being obtained w i t h the tableted form and the administration of the encapsulated drug producing blood levels intermediate between those obtained w i t h the solution and tablet forms. It w a s evident from their data t h a t the dispersion of the formulation contained w i t h i n the capsule w a s the rate determining s t e p i n the dissolution of the drug when u t i l i z e d i n this form. Very rapid dissolution rates were observed when the capsule contents were emptied and evenly dispersed throughout the dissolving media as compared t o the very slow dissolution rate observed when the i n t a c t capsule w a s placed i n the media. Similar findings i n tegard t o blood

Chap. 31

Biopha r m a c eu ti c s


337 -

levels obtained with encapsulated aspirin VS. tableted aspirin In this study, a significant delay in the appearance of salicylate in the blood was observed in those persons receiving aspirin in the form of capsules as compared with those receiving the analgesic in the form of tablets. In addition, the blood levels of total salicylate were lower in the group receiving the capsules than was found in those receiving the aspirin in the form of a tablet. Hollister and KanterTs compared enteric coated dosage forms of aspirin with compressed tablet preparations. They observed significant delays in onset of serum salicylate levels when the enteric coated preparations were employed. The delay in absorption found in their study was of such magnitude (three to six hours) that they concluded that enteric forms of salicylate should not be employed where an immediate analgesic or antipyretic effect was desired. Percutaneous Absorption: The influence of solubility and lipid/ water partition ratios in the percutaneous absor tion of the corticosteroids were studied by Katz and Shaikh. Fa The results of their study are in agreement with the theoretical postulates of Higuchi and their results show that the efficiency of percutaneous absorption absorption of the corticosteroids may be a function of the partition coefficient and the square root of the aqueous solubility. In their continuing studies pertaining to the factors influencing percutaneous absorption, Wurster and M u n i e ~ ~ have ~ , shown ~ ~ that the degree of hydration of the stratum corneum played an important role in the transport of methyl ethyl ketone. These workers have shown that dehydration delays percutaneous absorption while hydration of the skin above normal values enhances absorption. Thus, percutaneous as well as oral absorption of chemical substances appears to be a function of the lipid/water partition coefficient and aqueous solubility parameters of the diffusing moiety and intimately associated with the integrity and physico-chemical properties of the biological melldbranes. Drug Interactions: The interaction of dissolved drugs with either endogenous or exogenous materials present in the vicinity of the absorptive site may have a pronounced effect on the absorbability of the drug. Interaction of the drug with these materials may either facilitate or inhibit drug absorption. Sorby'' has shown that promazine adsorbed to the surface of both attapulgite and activated charcoal and this interaction of drug and adsorbent resulted in altered absorption patterns of promazine. When admixed with attapulgite, the absorption of promazine was significantly delayed, however, only minor decreases in the proportion of the administered dose absorbed was observed. On the other hand, when admixed with charcoal, the drug-adsorbent interaction resulted in both a decrease in the rate and the extent of absorption of promazine. Althou h absorption characteristics were not studied, BlaUg and crosse8 investigated the adsorption of antichlolinergic drugs by

were obtained by Wood.74

3 38 -

Sect. VI

-

Topics i n Chemistry


various antacids and found appreciable binding of atropine, methantheline, propantheline and oxyphenonium to the antacids, particularly magnesium trisilicate. In ldea of the frequent coadministration of anticholinergic drugs and antacids, definitive in vivo absorption studies are necessary to define the possible effects of the antacids on the therapeutic efficacy of the anticholinergic drugs. The intestinal absorption of water soluble dyes such as bromthymol blue, methyl orange and eosine-B and certain lipid soluble coTlexes of the dyes have been investigated by Levy and Matsuzawa.8 Their data suggests that the lipid/water partition ratio of the dye complexes did not reflect the intestinal absorption characteristics observed. The absorption characteristics of Certain metal-acid complexes of tetracycline and demethylchlortetracycline have also been investigated and it has been shown that some of the metal-acid-tetracycline complexes enhance the absorption of the tetracyclines.82 Diffusion: Diffusion of the drug from the site of dissolution to the absorbing surface may have a pronounced effect on the maintenance of the concentration gradient across the absorbing membrane and thus an effect on the rate of absorption. This parameter of the over-all absorption process was the subject of a report by Levy and J u ~ k o . ~ ~ These workers studied the oral absorption characteristics of both ethanol and salicylic acid in rats as a function of the viscosity of dissolving media. Their results indicated that diffusion of the drug molecules to the absorbing membrane was significantly decreased and the rate of gastrointestinal transit of the solutions was also decreased. Urinary Excretion: In lieu of the frequent use of urinary excretion data as an index of drug absorption and elimination rates in the evaluation of pharmaceutical dosage forms, it would appear to be of value to call the reader's attention to the recent works of Beckett et al.84resr8s pertaining to the excretion of drugs in man. These workers have investigated the influence of urinary PH and urine output on the renal excretion of several dru 8 . In regard to their studies on the excretion of amphetamine," the authors state that the alterations in excretion rates observed as a function of urinary pH and urine volume can be explained on the basis that the unionized portion of the amphetamine is reabsorbed by the Kidney and the passive reabsorption process is p H and volume dependent. The more alkaline the urine, the higher the percentage of unionized amphetamine present and hence a greater reabsorption of the drug and consequently a lawer excretion rate. Similar finding8 were reported by Beckett and collaborators for chlorpheniramine and methylamphetamine. 86 While these studies are largely applications and extensions of the basic studies reported much earlier,87 J 88 J 8s J 0 the kinetic approach to data evaluation and implications deduced from their findings throughout their reports are indicative of the value of these reports to the biopharmaceutical literature.

Chap. 31

Biopharmaceutic s

Higuchi, F i n g e r and Higuchi

339 -

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, 17

I. Higuchi, J. Pharm. Sci. 405 (1964). H. Y. Saad, J. Pharm. Sci., (1965). I. Higuchi, 1 3 (1 65 D. 0, Kildsig, -1491 ( 19k51. P. W. Taylor, 16m;.$670 (1965). P. w. Taylor and D. E. Wurster, 5, 1654, (1965). W, E. H a m l i n , E. Nelson, B. B a l l x a n d J. G. Wagner, Ibid, 2, 432 (1962). K. Sekiguchi and N. Obi, Chem. Pharm. B u l l . , 2, 866 (1961). K. Sekiguchi and N. O b i , and Y. Uyeda, Ibid, 12, 134 (1964). A. H. Goldberg M. Gibaldi and J. L. K a x JTPharm. Sci.,

W. I. Higuchi and H. Y. Saad and W. D. E. Wurster and D. E. Wurster and

54, 1145

m,

(1965).

s,

W. I. H i uchi, N. M i r , and S. J. Desai, J. Pharm. Sci., 1405 (19 5). E. Overton, Arch. ges P h y s r l . , Pfluger' 8 92, 115 ( 1902). R. Collander and ? I Barlun . A c t a Botan. Fenn. 11, 1 (1933). P. A. Shore, B, B. Brodie and C. A. M. Hogben, J. Pharmacol. Em. Ther. + ll 361 (1957). L. S. Schan er, P. A. Shore, B. B. Brodie and C. A. M. Hogben, a i d , 120, 528 (1957). C. A. M. H o g b e n L. S. Schander, D. J. Tocco and B. B. Brodie, Ibid, 120, 540 11957). L. S. Schander D. J. TOCCO, B. B. Brodie and C. A. M. Hogben, Ibid ' 123, 81 11958). B. B. Brodie and C. A. M. Hogben, J. Pharm. Pharmacol., 345

2

,

-

--

-

2,

( 1957)

R. Levine, Preliminary Studies on t h e R o l e of a Carrier i n t h e Transport of Quaternary Ammonium compounds. I n Proceedings of t h e F i r s t I n t e r n a t i o n a l Pharmacol i c a l Meeting, V o l . 4, Ed. Hogben. Oxford: Pergamon Press ( 19 2). L. So Schander, Annual Rev. of Pharmacol., 1, 29 (1961). D. H. Sqayth, Abs. and D i s t . of Drugs, T. B. Binns, Ed., E. and S. Livingston LTD, Pub. Edinburgh and London, Pg. 1, R.

3

( 19641.

B.

B.

Brodie,

D i d , Pg.

16, (1964).

5,

R. R. Levine a m . W. P e l i k a n , Annual Rev. of Pharmacol. E. Nelson, J. Pharm. Sci., 46, 60 19571 H, Fincher, J. G. Adams, and H? Beal, Ibid 4, 704 ( 1.965)

L.

64, 65. 66. L. J. Edwards, Trans. Faraday SOC., Q, l l g l T 5 1 % 67. E. Nelson and I. Schaldemose, J. Pharm. Sci., 48, 489 (1959) 68. G. Levy and B. A. Hayes, N.E. 1053 (1960). 69. E. B. T r u i t t and A. M. Morgan, J. Pharm. 70. S. V. Lieberman and J. H. 71. G. Levy and L. E. Hollister, 72. G. Levy and L. E. 730 B. Calesnick, B. Katchen

J.

.

Chap. 31

B i o p h a r m a c eutic s

cia,9

54,

74. 75.

J. H. Wood, I b i d , 1207 (1965). L. E. H o l l i s t e r and S. L. Kanter, C l i n .

76. 77. 78. 79

Katz and 2. I. Shaikh, J. Pharm. id, 5g1 Wurster and R. Munies, Ib 4 J 554 1965) .D. E. Wurster and R. M U n i e S , Ibid, , 1281 (1965

80.

81. 82.

a3.

84. 85 86. 87. 88. 89 90.

-6, M. D.

5 (1965).

E.

54,

Pharm.

and Therap.

L.

S. M.

,

(lm).

Sorby, I b i d , 677 BlaUg and M. Gross, G. Levy and T. Matsuzawa, E. G. Remers, W. C. Barringer, G. M. S i e g e r and A. Bid, 49 (1965). G. Levy and W. J. Jusko, I b i d , 54 219 (1965). A. H. Beckett and M. Rowland, J, Pharm. Pharmacol. D.

341

Higuchi, F i n g e r a n d Higuchi

53,

J

( 1965 A. H. Beckett and G.

17,

628

R.

H. Beckett and M. J. Orloff and R. W. B e r l i n e r , J. C l i n . Invest. M. H. Jacobs, Cold Spring Harbor Symposium, M. D. Milne, B. H. Scribbner and M. A. Crawford, Am. J. Med. 24, 709 (1958). W. J. Waddell and T. C. B u t l e r , J. C l i n . Invest. 36, 1217 A.

-

( 1957

g,

,

,

,

SUBJECT INDEX

Agents Which Affect Enzyme Activity, 277 Analgetics, Strong a n d Weak, 40 Anesthetics, G e n e r a l , 30 Angina P e c t o r i s , 78 Alkaloids, 31 1 Anorexigens, 51 Antiallergy Agents, 92 Antianginal Agents, 78 Anti-anxiety Agents, 1 Antiarrhythmic s, 8 5 Antibacterial Agents, Synthetic, 118 Antibiotic s, 109 Anticonvulsants, 30 Antidepr e s s a n t s, 12 Antidiabetics, 164 Antihypertensive Agents, 59 Anti-inflammatory Agents, non- s t e r o i d a l , 224 Antipara sitic Agents, Animal, 150 Antiparasitic Agents, Human, 136 Antipsychotic s, 1 Antiradiation Agents, 324 Antiviral Agents, 129 A t h e r o s c l e r o s i s , 178 Biopharmaceutic s, 33 1 Blood Enzymes, Agents affecting, 233

Cell Metabolism Regulation of, 267 Distribution of Drugs, F a t e and, 247 D i u r e t i c s , 67 Drug Receptor Interactions, Molecu l a r A s p e c t s of, 236 Enzyme Activity, Agents Which Affect, 277 F a t e and Distribution of Drugs, 247 G a s t r o i n t e s t i n a l Functions, Agents Affecting, 99 Hallucinogens, 12 Hormones, Non-steroidal a n d Antago n i s t s , 191 Hormones, Steroid a n d Antagonists, 21 3 Hypnotics, 30 Molecular A s p e c t s of Drug-Receptor Interactions, 236 Muscle Relaxants, 30 Nucleosides, 299 Nucleotides, 299 P e p t i d e s , Synthetic, 289 P h a r m a c e u t i c s , 331 P u l m o n a r y Agents, 92 Reactions of I n t e r e s t i n Medicinal C h e m i s t r y , 314 Regulation of Cell Metabolism, 267 Reproduction, 20 5 Sedative, 30 Stimulants, CNS, 12 Synthetic P e p t i d e s , 289

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