Acute effects of amitriptyline on human performance and interactions with diazepam.

The effects of psychomotor performance and attention of amitriptyline 75 mg administered without and with diazepam 10 mg have been investigated in 12 healthy subjects. The effects of the compounds were evaluated by objective tests (measurement of body sway, critical flicker fusion, visual reaction time, tachistoscopy, short term visual memory, tapping test, arithmetical calculation and Clement's code) and subjective measurements (visual analogue scales and side effects questionnaire). Measurements were taken before treatment and after 1, 3, 6, 8 and 24 h. Placebo did not affect either the objective or the subjective measurements. Diazepam caused a reduction in attention and performance after 1 h which had disappeared at 3 h. Amitriptyline caused a marked reduction in attention and performance, reaching a peak 3 hours after drug administration and persisting until 8 h. the deterioration in vigilance induced by amitriptyline was potentiated by concomitant diazepam.