The effect of repeated doses of temazepam and nitrazepam on human psychomotor performance.

The effects of six nightly doses of temazepam (20 mg), nitrazepam (10 mg) and placebo on saccadic eye movements, critical flicker fusion, choice reaction time and on subjective feelings were studied in a double blind cross-over study in eight volunteers. Testing was performed on nights 1 and 6 of treatment. Nitrazepam, a benzodiazepine with a long elimination half-life produced a residual performance impairment on night 1 that had disappeared by night 6, despite higher serum concentrations of the drug on the sixth night of treatment. Temazepam, with a shorter elimination half-life produced no significant performance impairment on night 1, but by night 6 a significant impairment of saccadic eye movements (P less than 0.05), was seen 1 h after drug intake. We conclude that tolerance developed to the sedative action of nitrazepam over the 6 night period of the study. No evidence of tolerance was seen with temazepam.