SUBJECTIVE RESPONSES TO D-AMPHETAMINE ALONE AND AFTER PIMOZIDE PRETREATMENT IN NORMAL, HEALTHY-VOLUNTEERS

The role of dopamine in d-amphetamine-induced euphoria has not been sy stematically examined in normal volunteers. Therefore, we examined the effects of the dopamine antagonist, pimozide, on responses to d-amphe tamine in healthy volunteers, using a within-subjects, double-blind de sign. Ten subjects received single oral doses of d-amphetamine (0, 10, 20 mg) 2 hours following pretreatment with pimozide (0, 1, 2 mg). Sub jective, behavioral, and physiological effects were assessed predrug a nd for 3 hours after d-amphetamine administration. d-Amphetamine alone produced prototypic effects on a variety of measures, including eupho ria and drug liking. Pimozide did not produce any effects when adminis tered alone and produced inconsistent effects on responses to d-amphet amine. Although higher doses of pimozide may be needed to antagonize t he euphorigenic effects of d-amphetamine, these results raise the poss ibility that the role of dopamine in the subjective effects of stimula nts may be more complex than initially appreciated.