Pharmacodynamic Effects of Buspirone and Clobazam

1. The pharmacodynamic effects of buspirone and clobazam were compared in two volunteer studies. Acute doses of buspirone 5 mg, 10 mg and clobazam 10 mg were contrasted with placebo and a verum (lorazepam 1 mg), in a repeated measures design with 10 subjects assessed on a battery of psychometric tests at 1.5, 3.5, and 5.5 h post dose. For the combined results clobazam and the lower dose of buspirone (5 mg) were significantly contrasted with lorazepam on measures of subjective sedation, memory and choice reaction time (CRT). The higher dose of buspirone was not statistically different from lorazepam for all measures except memory; whilst contrasting significantly with placebo and clobazam on movement and total reaction time components respectively. Though failing to achieve significance, a similar trend was seen for critical flicker fusion (CFF) with buspirone 10 mg and lorazepam producing the lowest scores indicative of increased sedation. 2. Repeated doses of buspirone 5 mg twice daily, clobazam 10 mg twice daily, or placebo twice daily for 8 consecutive days were compared on the same battery of psychometric tests in a repeated measures design. Nine subjects were assessed on days 1, 3, and 8 of the study. Overall, memory performance significantly decreased with buspirone 5 mg in contrast to both clobazam and placebo whilst the opposite trend was seen with CFF. Clobazam significantly improved TRT in contrast to both placebo and buspirone. 3. These results indicate improved reaction time and memory performance with repeated dosing of clobazam in contrast to buspirone. Impairment following acute administration of buspirone appears limited to the higher (10 mg) dose.