An investigation into the interaction between ethanol at low doses and the benzodiazepines nitrazepam and temazepam on psychomotor performance in normal subjects.

Ten healthy male volunteers received, in randomized order, temazepam 20 mg, nitrazepam 5 mg or placebo in combination with ethanol 0.1, 0.2 or 0.4 g/kg. Psychomotor tests were performed at regular intervals over 8 h. Ethanol alone at 0.4 g/kg significantly showed simple reaction time for between 30 and 60 min, whereas nitrazepam (5 mg) or temazepam (20 mg) plus the placebo alcohol dose (0.1 g/g) had no significant effect. The benzodiazepines and ethanol (0.2 and 0.4 g/kg) in combination showed no potentiation or prolongation of action. Both ethanol and the two benzodiazepines significantly reduced critical flicker detection in themselves and, in combination, had additive effects. Only nitrazepam and temazepam produced decreases in performance in the code substitution (DSST) test, and the time course of action of nitrazepam was markedly longer than that of temazepam. Ethanol alone had no detectable effect on immediate recall, prompted recall, learning, or word recognition tests. Both benzodiazepines reduced immediate and prompted recall and nitrazepam, in addition, reduced word recognition ability. It is concluded that the spectrum of CNS depressant actions of ethanol and the benzodiazepines are different and that there is no evidence of a potentiation or prolongation of their effects by concomitant administration of the doses used in the present study.