- Email: [email protected]
Anticoccidial drugs: Objectives of symposium on development, selection, and testing
EXPERIMENTAL
PARASITOLOGY
28, 1-3 ( 1970)
Anticoccidial Drugs: Development, W. Chairman
and Organizer,
University
Objectives Selection, Malcolm
Press Inc.
on Anticoccidial
Drugs
of Georgia, Athens, Georgia 30601
discard or to modify drastically an hypothesis. But we must be so prepared if we expect to make full use of the scientific method. In designing experiments for drug evaluations we need to bear in mind that the scientific method is most decisive if only one variable at a time is placed under test. If more than one is involved, troublesome interactions may be produced which complicate interpretation of results and which may require added control treatments. If a knowledge of two different factors or variables is required, it may be better to design separate experiments testing but a single variable in each experiment. Particularly when two different disease-producing organisms are involved, results may be confusing by interaction between the two organisms. Synergistic effects may be present or one organism may cancel or mask the action of the other. Although statistical methods have been developed for measuring interactions and removing them if the experiment is properly designed, every added variable makes of the results more the interpretation hazardous. Perhaps for this reason many of us are placing stronger reliance upon the battery-type experiment than on floor-pen or field experiments. Historically there have been at least three similar symposia held in the United States. The first one occurred 20 years ago, while two others took place 10 years ago. The first symposium sponsored by the 1
0 1970 by Academic
on
Reid
Symosium
We are happy to welcome this cosmopolitan group of coccidiologists to the campus of the University of Georgia. You represent a wide variety of affiliations and geographical areas. We have representatives from 11 countries. Men associated with regulatory governmental agencies of Canada, Great Britain, and the United States are present. They must make decisions involving governmental approval for use of anticoccidial drugs. We are happy to have other state and federal govemmental representatives engaged in research together with representatives of the poultry, feed, and pharmaceutical industries. The types of decisions confronting these various groups may be quite diverse, but the goals in producing better anticoccidial drugs and the methodology in evaluating them will be the same. All of us are dependent upon full use of the scientific method in these evaluation efforts. If there was ever an area of investigation requiring use of the scientific method, it is that of the selection and development of anticoccidial drugs. In dealing with a selflimiting disease, the misguided drug salesman has a “field day” if he can get his prospective customer to use some of his drug in treatment of coccidiosis. Even if the drug has no efficacy he will probably have a satisfied and returning customer. All the better for him if his customer has not been schooled in the necessity of controlled experiments. It is indeed difficult and painful for all of us to be prepared to
Copyright
of Symposium and Testing
2
REID
New York Academy of Sciences in November 1949 (Brackett 1949) contained reviews of many of the methods still used today. The honorary chairman, Dr. E. E. Tyzzer (1949) introduced the symposium by noting that the literature was well packed with misinformation when he started his investigations 30 years previously. Even after 50 years we still need to reconsider some misinformation currently existing today. Ten years later two other conferences were held on methods of testing anticoccidial drugs. In April 1959 Merck and Company held a conference on methods of testing coccidiostats at the Cheswold Farm in Dover, Delaware (Merck, Sharp & Dohme 1959). Although product-oriented, some valuable techniques were thoroughly described for the first time. In December of the same year a roundtable discussion was held under the auspices of the American Feed Manufacturers Association ( Hunter 1959). Faced with new problems imposed upon the feed manufacturers by the almost universal use of coccidiostats, they invited Dr. S. A. Edgar (1958) to address their group on “Considerations for the Evaluation of Coccidiostats.” The following year the roundtable discussion was followed up by a questionnaire on techniques answered by 26 investigators, several of whom are present today. During 1959 only two types of testing, laboratory and field trials, were discussed. Since that time an intermediate category of floor-pen trials has gradually become accepted. We shall divide our sessions into these three topics: battery, floor-pen, and field trials. As an additional topic, drug resistance will be considered in a fourth section. Finally, we shall then have a look at methods of combining results in selection of new coccidiostats and new methods of evaluation. In this final session we shall
ask your help in evaluating all of the different parameters used in testing anticoccidial drugs. Study and marking of this questionnaire will represent a final step. Tabulation of combined thinking of the group may assist all of us in making better judgments in the future. It does not seem desirable to the program committee that we attempt to agree upon a set of standards or criteria in this symposium. The program committee would like to suggest that we put aside as far as possible consideration of the superiority of any one specific product or of federal guide lines in our considerations. If we set our goal for the next two days on the scientific evaluation of methodology and techniques, we shall bc better equipped later to make necessary decisions. Through advanced planning with Experimental Parasitology, arrangements have been made to publish the major contributions of this symposium. We wish to acknowledge with thanks the financial support given by the pharmaceutical industry in underwriting costs of bringing speakers and participants for the symposium. The following made contributions : American Cyanamid Company, Princeton, N. J.; Ayerst Laboratories, New York, N. Y.; Chas. Pfizer and Co., Inc., Groton, Conn.; The Dow Chemical Co., Midland, Mich.; Eli Lilly and Company, Greenfield, Ind.; Hoffmann-LaRoche, Inc., Nutley, N. J.; Merck Institute for Therapeutic Research, Rahway, N. J.; The Norwich Pharmacal CO., Norwich, N. Y.; E. R. Squibb and Sons, Inc, Three Bridges, N. J.; and Sterwin Laboratories, Inc., New York, N. Y. REFERENCES BRACKETT, S. (ed.). 1949. Coccidiosis. Ann& of the New York Acdemy of Sciences 52, 431623. EDGAH, S. A. 1958. Problems in the control of coccidiosis. Proceedings of the Semiannual
OB JECIWES
Meeting of the American Feed Manufacturers Nutrition Council pp. 19-26. HUNTER, J. E. (Chairman). 1959. Considerations for the evaluation of coccidiostats. Proceedings of the 20th Annual Meeting of the Feed Manufacturers Nutrition American Council pp. 16-19.
OF
SYMPOSIUM
3
MERCK, SHARP & DOHME. Methods
of Testing
Farm, Dover,
1959. “Conference Coccidiostats;
Delaware.”
on
Cheswold
55 pp.
TYZZER, E. E. 1949. Comments by the Honorary Chairman. Coccidiosis Symposium. Annals of New York Academy of Sciences 52, 433.
PARASITOLOGY
28, 1-3 ( 1970)
Anticoccidial Drugs: Development, W. Chairman
and Organizer,
University
Objectives Selection, Malcolm
Press Inc.
on Anticoccidial
Drugs
of Georgia, Athens, Georgia 30601
discard or to modify drastically an hypothesis. But we must be so prepared if we expect to make full use of the scientific method. In designing experiments for drug evaluations we need to bear in mind that the scientific method is most decisive if only one variable at a time is placed under test. If more than one is involved, troublesome interactions may be produced which complicate interpretation of results and which may require added control treatments. If a knowledge of two different factors or variables is required, it may be better to design separate experiments testing but a single variable in each experiment. Particularly when two different disease-producing organisms are involved, results may be confusing by interaction between the two organisms. Synergistic effects may be present or one organism may cancel or mask the action of the other. Although statistical methods have been developed for measuring interactions and removing them if the experiment is properly designed, every added variable makes of the results more the interpretation hazardous. Perhaps for this reason many of us are placing stronger reliance upon the battery-type experiment than on floor-pen or field experiments. Historically there have been at least three similar symposia held in the United States. The first one occurred 20 years ago, while two others took place 10 years ago. The first symposium sponsored by the 1
0 1970 by Academic
on
Reid
Symosium
We are happy to welcome this cosmopolitan group of coccidiologists to the campus of the University of Georgia. You represent a wide variety of affiliations and geographical areas. We have representatives from 11 countries. Men associated with regulatory governmental agencies of Canada, Great Britain, and the United States are present. They must make decisions involving governmental approval for use of anticoccidial drugs. We are happy to have other state and federal govemmental representatives engaged in research together with representatives of the poultry, feed, and pharmaceutical industries. The types of decisions confronting these various groups may be quite diverse, but the goals in producing better anticoccidial drugs and the methodology in evaluating them will be the same. All of us are dependent upon full use of the scientific method in these evaluation efforts. If there was ever an area of investigation requiring use of the scientific method, it is that of the selection and development of anticoccidial drugs. In dealing with a selflimiting disease, the misguided drug salesman has a “field day” if he can get his prospective customer to use some of his drug in treatment of coccidiosis. Even if the drug has no efficacy he will probably have a satisfied and returning customer. All the better for him if his customer has not been schooled in the necessity of controlled experiments. It is indeed difficult and painful for all of us to be prepared to
Copyright
of Symposium and Testing
2
REID
New York Academy of Sciences in November 1949 (Brackett 1949) contained reviews of many of the methods still used today. The honorary chairman, Dr. E. E. Tyzzer (1949) introduced the symposium by noting that the literature was well packed with misinformation when he started his investigations 30 years previously. Even after 50 years we still need to reconsider some misinformation currently existing today. Ten years later two other conferences were held on methods of testing anticoccidial drugs. In April 1959 Merck and Company held a conference on methods of testing coccidiostats at the Cheswold Farm in Dover, Delaware (Merck, Sharp & Dohme 1959). Although product-oriented, some valuable techniques were thoroughly described for the first time. In December of the same year a roundtable discussion was held under the auspices of the American Feed Manufacturers Association ( Hunter 1959). Faced with new problems imposed upon the feed manufacturers by the almost universal use of coccidiostats, they invited Dr. S. A. Edgar (1958) to address their group on “Considerations for the Evaluation of Coccidiostats.” The following year the roundtable discussion was followed up by a questionnaire on techniques answered by 26 investigators, several of whom are present today. During 1959 only two types of testing, laboratory and field trials, were discussed. Since that time an intermediate category of floor-pen trials has gradually become accepted. We shall divide our sessions into these three topics: battery, floor-pen, and field trials. As an additional topic, drug resistance will be considered in a fourth section. Finally, we shall then have a look at methods of combining results in selection of new coccidiostats and new methods of evaluation. In this final session we shall
ask your help in evaluating all of the different parameters used in testing anticoccidial drugs. Study and marking of this questionnaire will represent a final step. Tabulation of combined thinking of the group may assist all of us in making better judgments in the future. It does not seem desirable to the program committee that we attempt to agree upon a set of standards or criteria in this symposium. The program committee would like to suggest that we put aside as far as possible consideration of the superiority of any one specific product or of federal guide lines in our considerations. If we set our goal for the next two days on the scientific evaluation of methodology and techniques, we shall bc better equipped later to make necessary decisions. Through advanced planning with Experimental Parasitology, arrangements have been made to publish the major contributions of this symposium. We wish to acknowledge with thanks the financial support given by the pharmaceutical industry in underwriting costs of bringing speakers and participants for the symposium. The following made contributions : American Cyanamid Company, Princeton, N. J.; Ayerst Laboratories, New York, N. Y.; Chas. Pfizer and Co., Inc., Groton, Conn.; The Dow Chemical Co., Midland, Mich.; Eli Lilly and Company, Greenfield, Ind.; Hoffmann-LaRoche, Inc., Nutley, N. J.; Merck Institute for Therapeutic Research, Rahway, N. J.; The Norwich Pharmacal CO., Norwich, N. Y.; E. R. Squibb and Sons, Inc, Three Bridges, N. J.; and Sterwin Laboratories, Inc., New York, N. Y. REFERENCES BRACKETT, S. (ed.). 1949. Coccidiosis. Ann& of the New York Acdemy of Sciences 52, 431623. EDGAH, S. A. 1958. Problems in the control of coccidiosis. Proceedings of the Semiannual
OB JECIWES
Meeting of the American Feed Manufacturers Nutrition Council pp. 19-26. HUNTER, J. E. (Chairman). 1959. Considerations for the evaluation of coccidiostats. Proceedings of the 20th Annual Meeting of the Feed Manufacturers Nutrition American Council pp. 16-19.
OF
SYMPOSIUM
3
MERCK, SHARP & DOHME. Methods
of Testing
Farm, Dover,
1959. “Conference Coccidiostats;
Delaware.”
on
Cheswold
55 pp.
TYZZER, E. E. 1949. Comments by the Honorary Chairman. Coccidiosis Symposium. Annals of New York Academy of Sciences 52, 433.