I vermectin and Abamectin

I vermectin and Abamectin

William C. Campbell Editor I vermectin and Abamectin With 66 Illustrations Springer-Verlag New York Berlin Heidelberg London Paris Tokyo

William C. Campbell Merck Institute for Therapeutic Research Rahway, N.J. 07065 Library of Congress Cataloging-in-Publication Data Ivermectin and abamectin I edited by William C. Campbell. p. cm. Includes index. ISBN-13:978-1-4612-8184-9 e-isbn-13:978-1-4612-3626-9 DOl: 10.1007/978-1-4612-3626-9 I. Ivermectin. 2. Abamectin. I. Campbell, William C. (William Cecil), 1930- SF918.183I94 1989 636.089'6964061--dc20 89-6254 CIP 1989 by Springer-Verlag New York Inc. Softcover reprint of the hardcover 1st edition 1989 All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer-Verlag, 175 Fifth Avenue, New York, New York 10010. U.S.A.), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use of general descriptive names, trade names, trademarks, etc. in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone. While the advise and information in this book are believed to be true and accurate at the date of going to press, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Typeset by TCSystems, Inc., Shippensburg, PA. 9 8 7 6 5 4 3 2 1

Dedicated to the memory of the late Mr. Robert K. Hartman and the late Mr. Robert E. Ormond, who contributed to the discovery of the avermectins, and to the late Dr. Mohammed A. Aziz, who directed the clinical evaluation of ivermectin in humans.

Preface Ivermectin was introduced to the marketplace as an antiparasitic drug in 1981, and abamectin was introduced as an agricultural pesticide (and as an antiparasitic drug) in 1985. They are both members of the avermectin family of compounds, and their impact has been enormous. The efficacy of ivermectin against nematode and arthropod parasites is unprecedented i{l potency and breadth of spectrum. Its worldwide acceptance in livestock production and in the health care of companion animals has made it a major commercial success. Its efficacy in human onchocerciasis (river blindness) has made it a promising candidate for the control of one of the most insidious and intractable of tropical diseases. Abamectin is in commercial use as an agricultural pesticide, and its applications are continuing to expand. Most striking of all, perhaps, is the intense scientific activity triggered by the discovery of the avermectin compounds. In the fields of chemistry, microbiology, parasitology, entomology, biochemistry, pharmacology, and the clinical and agricultural sciences, interest in the avermectins has evolved rapidly, and a considerable bibliography has already been amassed. Chemicals that are widely used raise correspondingly wide concerns about safety-and the ongoing evaluation of the avermectins thus far has included not only studies on the safety of the compounds for the animals, plants, and people in which they are used but also studies on their safety for the people who make and apply them, safety for the people who eat the plants and animals to which these agents have been applied, and safety for the environment which is exposed, one way or another, to their effects. Given the intense industrial and scientific interest in ivermectin and abamectin, and the likelihood that they will be the forerunners of an expanding family of relatives and descendants, it seems timely to take stock of what we have learned about them so far. With few exceptions, the authors of this book are members of the scientific staff of the Merck Sharp & Dohme Research Laboratories; and there were reasons for this. In certain disciplines, such as toxicology and fermentation technology, most of the available information on the aver-

viii Preface mectins has been obtained by MSDRL scientists, and they are therefore in a good position to review the data. The toxicological and environmental safety data that have been accumulated within our laboratories have been made available to governmental regulatory agencies and other interested parties in the form of official reports, but have seldom appeared in the scientific literature. In other disciplines, much information already has appeared in the scientific literature; but here, too, a large proportion of the research has been carried out by, or in collaboration with, our own scientists-and the names of those individuals inevitably came to mind as prospective authors of review chapters. There was, moreover, a practical advantage in the preponderance of MSDRL authors: the chapters could be prepared synchronously. The editor knows, from hard-won experience, the difficulty of getting manuscripts from far-flung scribes with no obligation other than a cheerfully and hastily given promise to write a chapter for a particular volume. In some multiauthored books, a chapter written by a conscientious contributor may be older by many months, or even by a few years, than one written by some hopelessly delinquent contributor. In the present case, the editor has been blessed with colleagues who have been willing to make an extraordinary effort to bring their labors to fruition at the same time. This book, then, comes close to the objective of capturing a likeness of its subject at one instant in time. Except in the context of synthetic and microbiological chemistry (which must of necessity deal with structural diversity), this volume deals almost exclusively with ivermectin and abamectin-not with the extended family of the avermectins or with the related family known as milbemycins. The expression of dosage in terms of micrograms (f.lg) per kilogram of body weight has become commonplace in accounts of the efficacy of these compounds, and this form is generally used in this book. Toxicological studies, however, usually deal with multiples of milligrams, rather than fractions, and in that context dosages are expressed in terms of milligrams (mg) per kilogram of body weight. The chapters of the book have been arranged in three groups. The first deals with the basic chemical, biochemical, and microbiological aspects; the second deals with pharmacological, safety, and environmental aspects; and the third covers practical use of the compounds as antiparasitic and pesticidal agents. In the case of human application, however, the available safety data have emerged from the clinical experience, and are to be found in Part III. William C. Campbell

Acknowledgments The editor thanks Dr. Harold D. Hafs, Vice-President of Animal Science Research, Merck, Sharp & Dohme Research Laboratories, and Dr. Mark Licker, Executive Editor, Springer-Verlag, for their support and counsel throughout the preparation of this volume. He is indebted to Dr. M.H. Fisher for preparation of the introductory statement on Nomenclature and Physical Properties and to Dr. Dennis J. Underwood for the computer-generated structural models that appear on the cover.

Contents Preface vii Part I Chapter 1. Chapter 2. Chapter 3. Chapter 4. Chemistry M.H. Fisher and H. Mrozik 1 Isolation and Characterization of the Producing Organism R. W. Burg and E.O. Stapley 24 Fermentation Development and Process Improvement Mary Nallin Omstead, Louis Kaplan, and Barry C. Buckland 33 Biosynthesis S.T. Chen, O.D. Hensens, and M.D. Schulman 55 Chapter 5. Part II Chapter 6. Chapter 7. Chapter 8. Mode of Action of Ivermectin M.J. Turner and J.M. Schaeffer Toxicology George R. Lankas and Lea R. Gordon Pharmacokinetics of I vermectin in Animals and Humans David W. Fink and Arturo G. Porras Metabolism and Tissue Residues Shuet-Hing Lee Chiu and A. Y.H. Lu 73 89 113 131

xii Chapter 9. Chapter 10. Chapter 11. Chapter 12. Chapter 13. Chapter 14. Contents Chemical Assay for Ivermectin in Edible Tissues George V. Downing 144 Safety of I vermectin in Target Animals J.D. Pulliam and J.M. Preston 149 Environmental Aspects of I vermectin Usage in Livestock: General Considerations B.A. Halley, R.J. Nessel, and A.Y.H. Lu 162 Environmental Aspects of Use of Ivermectin and Abamectin in Livestock: Effects on Cattle Dung Fauna R.A. Roncalli 173 Environmental Aspects of Abamectin Use in Crop Protection P.G. Wislocki, L.S. Grosso, and R.A. Dybas 182 Worker Safety Aspects of Abamectin Use in Crop Protection L.S. Grosso, R.A. Dybas, and S.F. Rickard 201 Part III Chapter 15. Chapter 16. Chapter 17. Chapter 18. Chapter 19. Chapter 20. Use of Ivermectin in Cattle, Sheep, Goats, and Swine G. W. Benz, R.A. Roncalli, and S.J. Gross 215 Use of Abamectin in Cattle. G. W. Benz and J.L. Cox 230 Use ofivermectin in Horses W.C. Campbell, W.H.D. Leaning, and R.L. Seward 234 Use ofivermectin in Dogs and Cats W.C. Campbell 245 Use of Ivermectin in Laboratory and Exotic Mammals and in Birds, Fish, and Reptiles M.D. Soli 260 Abamectin Use in Crop Protection R.A. Dybas 287

Contents xiii Chapter 21. Use of Ivermectin in Humans B.M. Greene, K.R. Brown, and H.R. Taylor 311 Appendixes I: The Determinative Method for Assaying Ivermectin Residues in Tissue and Plasma George V. Downing 324 II: Confirmatory Assay for Assaying Ivermectin Residues in Liver George V. Downing 336 III: List of Registrations J. Di Netta Subject Index 344 347

Contributors G.W. BENZ, Ph.D. Department of Animal Science Research, Merck Sharp & Dohme K.R. BROWN, M.D. Department of Clinical Research, Merck Sharp & Dohme Research Laboratories, West Point, Pennsylvania 19486 BARRY C. BUCKLAND, Ph.D. Department of Biochemical Process Research and Development, Merck Sharp & Dohme R.W. BURG, Ph.D. Department of Basic Microbiology, Merck Institute for Therapeutic Research, Rahway, New Jersey 07065 WILLIAM C. CAMPBELL, Ph.D. Department of New Drug Discovery, Merck Institute for Therapeutic Research, Rahway, New Jersey 07065 S.T. CHEN, Ph.D. Department of Fermentation Microbiology, Merck Sharp & Dohme SHUET-HING LEE CHIU, Ph.D. Department of Animal Drug Metabolism, Merck Sharp & Dohme J.L. Cox, Ph.D. Department of Animal Science Research, Merck Sharp & Dohme

xvi Contributors J. DI NETTA, J.D. Department of Regulatory Affairs, Merck Sharp & Dohme Research Laboratories, Rahway, New Jersey 07065 GEORGE V. DOWNING, Ph.D. Department of Analytical Research, Merck Sharp & Dohme Research Laboratories, Rahway, New Jersey 07065 R.A. DYBAS, Ph.D. Department of Agricultural Research, Merck Sharp & Dohme Research Laboratories, Three Bridges, New Jersey 08887 DAVID W. FINK, Ph.D. Department of Animal Formulation Development, Merck Sharp & Dohme M.H. FISHER, Ph.D. Department of Synthetic Chemistry Research, Merck Sharp & Dohme LEA R. GORDON, D.V.M., Ph.D. Department of Safety Assessment, Merck Sharp & Dohme Research Laboratories, West Point, Pennsylvania 19486 B.M. GREENE, M.D. Division of Geographic Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35205 S.J. GROSS, Ph.D. Department of Animal Science Research, Merck Sharp & Dohme L.S. GROSSO, Ph.D. Department of Agricultural Research, Merck Sharp & Dohme Research Laboratories, Three Bridges, New Jersey 08887 B.A. HALLEY, Ph.D. Department of Animal Drug Metabolism, Merck Sharp & Dohme O.D. HENSENS, Ph.D. Department of Natural Product Chemistry, Merck Sharp & Dohme

Contributors xvii LOVIS KAPLAN, Ph.D. Department of Fermentation Microbiology, Merck Sharp & Dohme GEORGE R. LANKAS, Ph.D. Department of Safety Assessment, Merck Sharp & Dohme Research Laboratories, West Point, Pennsylvania 19486 W.H.D. LEANING, B.V.Sc. Department of Technical Services, MSD AGVET, Rahway, New Jersey, 07065 A.Y.H. Lu, Ph.D. Department of Animal Drug Metabolism, Merck Sharp & Dohme H. MROZIK, Ph.D. Department of Synthetic Chemistry Research, Merck Sharp & Dohme M. NALLIN OMSTEAD, Ph.D. Department of Fermentation Microbiology, Merck Sharp & Dohme R.J. NESSEL, Ph.D. Department of Regulatory Affairs, Merck Sharp & Dohme Research Laboratories, Rahway, New Jersey 07065 ARTURO G. PORRAS, Ph.D. Department of Drug Metabolism, MerSharp & Dihme Research Laboratories, West Point, Pennsylvania 19486 J.M. PRESTON, B.V.M.S., Ph.D. Department of Animal Science Research, Merck Sharp & Dohme J.D. PULLIAM, D.V.M., Ph.D. Department of Animal Science Research, Merck Sharp & Dohme S.F. RICKARD, Ph.D. Department of Agricultural Research, Merck Sharp & Dohme Research Laboratories, Three Bridges, New Jersey 08887

xviii Contributors R.A. RONCALLI, D.V.M. Department of Animal Science Research, Merck Sharp & Dohme J.M. SCHAEFFER, Ph.D. Department of Biochemical Parasitology, Merck Sharp & Dohme M.D. SCHULMAN, Ph.D. Department of Fermentation Microbiology, Merck Sharp & Dohme R.L. SEWARD, D.V.M. Department of Animal Drug Evaluation, Merck Sharp & Dohme M.D. SOLL, B.V.Sc. Department of Animal Science Research, Merck Sharp & Dohme E.O. STAPLEY, Ph.D. Department of Basic Microbiology, Merck Institute for Therapeutic Research, Rahway, New Jersey 07065 H.R. TAYLOR, M.D. Dana Center for Preventive Ophthalmology, The Wilmer Institute, The Johns Hopkins University, Baltimore, Maryland 21205 M.J. TURNER, Ph.D. Department of Biochemical Parasitology, Merck Sharp & Dohme P.G. WISLOCKI, Ph.D. Department of Agricultural Research, Merck Sharp & Dohme Research Laboratories, Three Bridges, New Jersey 08887

NOMENCLATURE AND PHYSICAL PROPERTIES NATURAL A VERMECDNS ORS components A: R5 = CH 3 components B : Rs = H components 1: X = -CH=CH OH components 2: X = -CH 2 th- components a : R26= C 2 H 5 components b : R 26= CH 3 ARAMECDN Synonyms: Avermectin B, ; AVM; C-076; MK-936. Trade names: AVID AGRI-MEK VERTIMEC AVOMEC Abamectin contains at least 80% of avermectin B'a and not more than 20% of avermectin B,b. Avermedin R.. C48Hn O,4; mol wt: 872. ott-white powder; [alo + 55.7 ± 2 (c = 1.06 in chloroform); uv max (methanol): 237, 243, 252 nm (E 29, 120; 31,850; 20,510). Avermedin Rib mol. wt. 858.

IVERMECON OH Synonyms: 22.23-Dihydroavermectin BI; 22.23-dihydro C-076BI; MK-933; Trade names: HEARTGARD30 ;CARDOMEC :EQYALAN ; IYOMEC. ; ZIMECTERIN ; MECTIZAN Semisynthetic derivative of the avermectins. q.v. Ivermectin contains at least 80% of 22.23- dihydroavermectin Bla and less than 20% of 22.23-dihydroavermectin BIb. Off-white powder; [aid + 71.5 ± 3 (c = 0.755 in chloroform); uv max (methanol): 238. 245 nm (f; 27.100; 30.100). Component 810 (MK-932) mol. wt. 874 5-0-Demethyl-22.23-dihydroavermectin Ala; 22.23-dihydroavermectin Bla; 22.23-dihydro C-076B la Crystals from ethanol/water. m.p. 1545-157 C Composeat 8110 mol. wt. 860 5-O-Demethyl-25-deO-methylpropyl)-22.23-dihydro-25-( I-methylethyl)avermectin Ala; 22.23- dihydroavermectin BIb