Drug preference and mood in humans: d-amphetamine.

A total of 31 normal human volunteers participated in a nine-session experiment. During the first four sessions, they received alternately 5 mg d-amphetamine or placebo. During the next five sessions, they were given a choice between amphetamine and placebo. Subjective effects were assessed using the Profile of Mood States (POMS) before the drug was taken and 1, 3, and 6 h later. Subjects chose amphetamine a mean of 4.03 times. Compared with placebo, amphetamine produced changes in mood on the POMS including increased Vigor, Elation, Friendliness, Arousal and Positive Mood and decreased Confusion. These differences were greatest 3 hr after ingestion. Mood changes produced by d-amphetamine were comparable in all subjects regardless of the actual number of times each chose the drug. These data suggest that that subjective effects do not predict drug choice. The results are discussed in terms of developing methods for predicting the abuse potential of psychotropic drugs.