Drug toxicity and its impact on drug evaluation in man

A necessary concomitant of the rapid expansion of therapeutics witnessed over the past decade has been the introduction of large numbers of new drugs into clinical trial. New expressions of drug toxicity have been the “biologic price” of this progress. In an attempt to meet this challenge, animal toxicologic procedures have been greatly expanded and the current methods are briefly outlined. It is clear, however, that, although these animal studies may eliminate frankly pOisonous material from human trial, “safety” in animals does not eliminate idiosyncrasy, allergy, and other more subtle reactions in humans. Thus, the adverse effects of new drugs must be actively sought as an integral part of clinical studies. A classification of drug toxicity organized to indicate the stages of clinical trials in which the specific types of reactions might be expected to appear is presented. On the other hand, tOXicity in animals is not conclusive evidence that a given drug will be toxic for man. Indeed, many important currently used medications are highly toxic in one or more species of animals. Thus, rigid interpretation of animal data could seriously hamper the progress which holds so much promise for the future.