ABSTRACT
This chapter examines how chemically active drugs do not always behave as they should and why their effects vary considerably from one individual or one situation to the next. Paradoxical drug responses of the kind illustrate the difficulty of rigidly classifying psychotropic drugs as depressant, stimulant, tranquillizing and so on. In most drug experiments, of course, the dose and route of administration is standardized and the variation in response observed is mainly due to other factors. The potency of psychological influences on drug response has been demonstrated in a number of experiments designed in such a way that the normal effect of a drug is deliberately distorted by giving misleading information to the experimental subjects. Group-interaction effects on human drug response have been studied in some ingenious experiments which have tried to isolate the separate influence of pharmacological and social factors.
