PROGRESS IN MEDICINAL CHEMISTRY 2 ENGLAND : BUTTERWORTH & CO. (PUBLISHERS) LTD. LONDON: 88 Kingsway, W.C.2 AFRICA: BUTTERWORTH & CO. (AFRICA) LTD. DURBAN: 33 35 Beach Grove AUSTRALIA: BUTTERWORTH & CO. (AUSTRALIA) LTD. SYDNEY: 6-8 O’Connell Street MELBOURNE: 473 Bourke Street BRISBANE: 240 Queen Street CANADA : BUTTERWORTH & CO. (CANADA) LTD. TORONTO : 1367 Danforth Avenue, 6 NEW ZEALAVD: BUTTERWORTH & CO. (NEW ZEALAND) LTD. WELLINGTON: 49/51 Ballance Street AUCKLAND: 35 High Street U.S.A.: BUTTERWORTH INC. WASHINGTON, D.C. : 7235 Wisconsin Avenue, 14 PROGRESS IN MEDICINAL CHEMISTRY 3 Edited by G. P. ELLIS, B.Sc., Ph.D., F.R.I.C. Research Department, Benger Laboratories Limited Holmes Chapel, Cheshire and G. B. WEST, B.Pharm., D.Sc., Ph.D. School of Pharmacy, University of London LONDON BUTTERWORTHS 1962 Suggested U.D.C. number: 615.7:54 0 Butterworth & Co. (Publishers) Limited 1962 Made and printed in Great Britain by Taylor Garnctt Evans d Co. Ltd. Walford, Herlfordshire PREFACE IN presenting the second volume of this series, we have continued the efforts made in Volume 1 to provide a collection of reviews on topics of importance to scientists interested in one or more of the many disciplines connected with drugs-from their discovery to their use in medicine. The first chapter is devoted to the patenting of chemicals as drugs-a subject of some importance to chemists engaged in the synthesis of potential new drugs but one which is often too little understood. The review on the mechanisms of neuromuscular blockade, although necessarily written with a biological stress, is of value to the chemist in that it illustrates the complexity of the reactions involving voluntary movement. The testing and development of analgesic drugs represents an important section of medicinal chemistry and one on which much time and money has been spent in man’s efforts to secure agents to relieve pain. The reviews on neuromuscular blockade and anal- gesics are to be followed in a future volume by others complementary to them, and these will include the chemical aspects. The chapter on anaphylaxis contains the latest information in this field, written, it is hoped, in a way in which a non-biologist can form some idea of the complex biological basis of this phenomenon; so many violent and even fatal anaphylactic reactions in patients are recorded each year that it is essential for the chemist to understand some of the processes involved as he is often called upon to prepare antagonists to these. One of the mechanisms involving adrenergic blockade is dealt with in the review of halogeno- alkylamines, but it is important to remember that newer compounds have now been shown to prevent the release of the neurohormones and may therefore be of even more value in hypertension than the halogenoalkyl- amines. All of the reviews are written by specialists and each reflects the author’s chief interest. We are grateful to reviewers of the first volume for the warm reception given to it and to the staff of Butterworths for their encouragement and help in many directions. We also wish to thank the authors, societies and pub- lishers for permission to use illustrations and tables which have appeared in previous publications. G. P. ELLIS G. B. WEST November 1961 V This Page Intentionally Left Blank CONTENTS Prejiie 1. THE PATENTING OF DRUGS F. MURPHY,B.Sc., F.C.I.P.A., A.R.I.C., Patents Department, Fisons Limited, Felixstowe Introduction 1 Patentable inventions 3 Procedure for securing a United Kingdom patent 7 General 7 Examination 9 Opposition 10 Fees 11 Procedures for securing an overseas patent 12 General 12 United States of America 13 France 17 Germany 18 The specification 19 The provisional specification 19 The complete specification 21 The claims 23 The inventor 24 Scope of the monopoly 27 Selection inventions 29 The patent after grant 33 Infringement 33 Licences 34 Restrictive conditions 35 Limited licences 36 Label licences 36 Compulsory licences 36 General 37 Revocation 39 2. THE TESTING AND DEVELOPMENT OF ANALGESIC DRUGS A. H. BECKETT, D.Sc., Ph.D., F.R.I.C., F.P.S., and A. F. CMY, B.Sc., Ph.D., F.R.I.C., F.P.S., School of Pharmacy, Chelsea College of Science and Technology, London, S. W.3 Introduction 43 Tests for analgesic activity 44 Animal tests 46 Tests in man 48 Tests for addictive liability 50 Classes of analgesic drugs 52 Morphine derivatives 52 Morphinans and isomorphhans 56 Benzomorphans 58 Pethidine and derivatives 61 vii Norpethidine derivatives 63 Reversed esters of pethidine 68 Diphenylpropylamines 71 Benzimidazoles 77 Reduced isoquinolines 79 Conclusions 80 3. MECHANISMS OF NEUROMUSCULAR BLOCKADE W. C. BOWMAN,Ph.D., Department of Pharmacology, School of Phamzacy, University of London Introduction 88 Resting potential and action potential in nerve and muscle 88 Neuromuscular transmission 91 The neuromuscular junction 92 Synthesis of acetylcholine 94 Release of acetylcholine 94 Function of acetylcholine 95 Methods of producing neuromuscular block 96 Reduction of transmitter output from nerve 96 Motor end-plate block 99 Screening of neuromuscular blocking agents 109 Clinically useful neuromuscular blocking agents 118 Curare-like blocking agents 120 Depolarizing blocking agents 122 4. 2-HALOGENOALKYLAMINES J. D. P. GRAHAM,B.Sc., M.D., F.R.F.P.S., F.R.C.P. (E), Departmt of Pharmacology, Welsh National School of Medicine, Cardif/ Introduction 132 The multiplicity of receptors 134 Peripheral antagonists of the excitor actions of catecholamines 136 Dibenamine 136 Pharmacological actions of 2-halogenoalkylamines 138 Antagonism of injected adrenaline and noradrenaline and of the effects of stimulation of adrenergic nerves 138 Antagonism of histamine and 5-hydroxytryptamine 143 Antagonism of other sympathomimetic amines 145 Other actions of 2-halogenoalkylamines 146 Chemistry of 2-halogenoalkylamines 147 Synthesis of arnines and intermediates 147 Chemical structure and pharmacological activity 148 Structural requirements for optimal activity 156 Pharmacological activity and chemical reactivity in 2-halogenoalkylamines 157 The iminium ion 157 The ethanolamine component 158 The piperazinium form 158 Vinylamine 159 General comments 160 Stability of 2-halogenoalkylamines 162 Mode of action of 2-halogenoalkylamines 162 Interaction with amines 166 Therapeutic uses of 2-halogenoalkylamines 166 Conclusion 171 ... Vlll 5. ANAPHYLACTIC REACTIONS G. E. DAVIES,B. Sc., Imjerial Chemical Industries Limited (Pharmaceuticals Division) Alderley Park, Macclesjeld, Chshire Introduction 176 Definitions 176 Antigen-antibody combination 177 Delayed hypersensitivity 178 Types of anaphylaxis 178 Anaphylaxis in different species 180 Methods of producing anaphylaxis 181 Preparation of antisera 181 Active sensitization 182 Cutaneous anaphylaxis 182 Anaphylactic microshock 184 Lethal shock after intravenous injection of antigen 184 Mechanisms of anaphylaxis 184 Sensitization 184 Combination of antigen with antibody 186 Complement 186 Mediators 187 Inhibition of anaphylaxis 192 Allergy in man 195 Index 199 ix This Page Intentionally Left Blank I THE PATENTING OF DRUGS F. MURPHY INTRODUCTION THEword ‘patent’ is the short form of ‘Letters Patent’, a term derived from the Latin literaepatentes meaning ‘open letters’. The letters patent are so called because these documents are not sealed up but are exposed to view, with the Great Seal attached to the document. Letters patent are used to make the grant of dignities, territorial titles, appointments to certain Offices of State, and privileges of various kinds including monopoly rights in inventions. Originally, letters patent for inventions carried the Great Seal of the United Kingdom, but since 1883 the seal of the Patent Office has been substituted for the Great Seal. The grant of monopolies by the Crown extends far back in history, and the United Kingdom was one of the first countries to grant monopolies or patents in respect of inventions. The first Act which provided specifically for the grant of patents for inventions was the Statute of Monopolies passed in 1623 during the reign of King James I. In effect this Statute terminated the numerous monopolies previously granted in respect of normal articles of commerce, but provided that monopolies could still be granted for inventions. However, little development took place during the next 200 years, and the main growth of the patent monopoly system followed the Industrial Revolu- tion and the accompanying development in science and technology. Thus, the Patent Law Amendment Act of 1852 provided for the filing of a provi- sional specification which could be followed by a complete specification, and the requirement of a description of his invention from the applicant. Before this, a patent was obtained on the title of the invention, such as: ‘Certain improvements in machinery for spinning cotton and like fibrous substances’. The next stage came with the Patents Act of 1883, in accordance with which the fee payable on the filing of an application was reduced to El, and the fee on the filing of a complete specification, to &3. Furthermore, this Act provided for the establishment of the Patent Office in its present form. Another important development was the passing of the Patents and Designs Act 1907, which introduced for the first time the examination of patent applications for novelty, this examination being restricted to British patents published in the preceding fifty years before the date of the application. The Act also prohibited the claiming of chemical compounds per se and included legislation for the grant of compulsory licences in respect of patents concerned with food or medicine. The Patents and Designs Act was later amended by various Acts, for example those of 1919, 1928, 1932, 1938 and 1942, but remained in force until it was repealed and replaced by the Patents Act 1949. One of the most important changes introduced by the 1949 Act was that chemical compounds 1 THE PATENTING OF DRUGS per se may be claimed, thus reversing the situation which had existed since the 1907 Act.