The effect of clobazam and lorazepam on the psychomotor performance of anxious patients.

Psychomotor performance and anxiety were measured in 70 anxious outpatients in a randomized double-blind, placebo-controlled trial comparing the 1,5-benzodiazepine clobazam (10 mg twice a day) to lorazepam (1 mg twice a day). Carefully selected tests were administered pre-treatment and at 2 and 9 days after treatment. Compliance was checked by blood assays. All three treatment groups (clobazam, lorazepam and placebo) showed a significant improvement in anxiety over the course of the trial. There were no significant differences between the groups in terms of anxiety reduction. All three groups improved over the course of the trial in choice reaction time, digit symbol substitution test, Purdue pegboard test (both hands) and in the Inglis paired-associate learning test: there were no significant differences between the groups with regard to these tests. There was no change in critical flicker fusion threshold over the trial period in any of the three groups. The placebo and clobazam groups showed a significant improvement in two of the Purdue pegboard tests (preferred hand and assembly) from pre-treatment to 2 days but no further improvement at 9 days. The lorazepam group, however, showed no improvement in these two tests from pre-treatment to 2 days; a significant improvement only emerged between the 2-day and 9-day assessments. This might reflect an initial, transient sedation in the lorazepam-treated patients. Generally, we failed to demonstrate any consistent impairment in psychomotor performance with either clobazam or lorazepam in our anxious patients. These findings contrast with those obtained after administration of 1,4-benzodiazepines (e.g., lorazepam) to normal volunteers and they suggest that data from the latter cannot necessarily be extrapolated to anxious patients.