The effects of repeated doses of clomipramine and alprazolam on physiological, psychomotor and cognitive functions in normal subjects.

The effects of a 10 day administration of clomipramine (25-50 mg t.i.d.), alprazolam (0.25-0.75 mg t.i.d.) and placebo were assessed in normal volunteers in a double-blind cross-over study. A battery of physiological, psychomotor and cognitive tests was administered both before and 3 h after drug on days 1, 5 and 10. The effects of alprazolam on EEG and evoked potentials were characteristic of benzodiazepines; clomipramine had little effect. In contrast, reaction speed was markedly slowed by clomipramine but little affected by alprazolam. Neither drug produced any accumulation of effect on a verbal recall task but neither did tolerance develop to the acute impairments produced by active treatments. Alprazolam produced an increase in levels of forgetting, especially on day 5. Subjective ratings for mood and bodily symptoms were adversely affected by clomipramine but little altered by alprazolam. It is suggested that some of the differences between drug treatments may be due to differences in the speed of onset of tolerance.