Tofisopam, a novel 3,4-benzodiazepine: multiple-dose effects on psychomotor skills and memory. Comparison with diazepam and interactions with ethanol.

Twelve healthy male volunteers were treated (double-blind crossover design) with tofisopam (a new 3,4-benzodiazepine), diazepam, or placebo, on 2 consecutive days each. Psychomotor skills were impaired after a single dose of diazepam (10 mg) given on day 1. Measurements on day 2 showed that some tolerance had developed to the diazepam-induced impairment of reactive and coordinative skills, but not to its effects on flicker fusion or on the extraocular muscle balance. Tofisopam failed to impair performance both as a single dose (100 mg) and after repeated doses (100 + 50 + 50 + 100 mg). The subjects felt more fatigue, dizziness, calmness, and passiveness after diazepam than after tofisopam. When either drug was given together with 0.8 g/kg ethanol on day 2, the breath ethanol concentrations were 0.7--1.0 mg/ml and all psychomotor skills were impaired. Diazepam + ethanol particularly impaired memory and learning as well. After this combination the subjects were classified (time anticipation test) as 'disqualified drivers' more often than after placebo. It is concluded that diazepam, as well as either benzodiazepine with ethanol, may reduce the ability to drive vehicles or operate machinery.