Impaired performance and sedation after a single dose of lorazepam.

In a double-blind cross-over study using normal student volunteers, the effects of 1 and 2.5 mg lorazepam on self-rated mood and bodily symptoms, as well as performance in a number of tests were assessed. Both doses significantly increased self ratings of physical and mental sedation, the effects being more marked 4 h after drug administration than after 1 h. Lorazepam impaired simple reaction time, verbal learning, number cancellation, symbol copying and performance in the digit-symbol substitution test. The impairments were greater with the 2.5 mg dose and were more marked 4 h after drug administration than after 1 h.