Double-blind comparative clinical trial of pimozide and chlorpromazine in mania. A test of the dopamine hypothesis.
Pimozide (PMZ), a relatively specific dopamine (DA) receptor blocking drug, was compared to chlorpromazine (CPZ) in a double-blind, between-patient clinical trial in mania. The trial lasted 14 days. Twenty-three patients who fulfilled Feighner's criteria for mania entered the trial (one patient entering on two separate occasions). Both drugs led to clinical improvement, with a significant effect being noted within 24 hours. According to one of the two rating scales used, initial improvement was greater with chlorpromazine, probably due to its greater sedative effect. By 7 days both drugs were equally effective. Sedative side effects were more frequent in patients on CPZ; extrapyramidal side effects were more frequent with PMZ. The finding that the relatively specific DA receptor blocking drug PMZ was as effective as CPZ in the treatment of mania is consistent with the view that hyperactivity of central DA pathways is involved in the pathogenesis of this condition.