Immediate and overnight effects of zopiclone 7.5 mg and nitrazepam 5 mg with ethanol, on psychomotor performance and memory in healthy volunteers.

The effects of ethanol (0.2-0.4 g/kg) taken in conjunction with a single nocturnal dose of zopiclone 7.5 mg or nitrazepam 5 mg, on the early morning performance were investigated by means of psychomotor tests in 9 female volunteers. While there was no noticeable difference in the Choice Reaction Time (CRT) for any of the drug-ethanol combinations and ethanol alone, the zopiclone combination appeared to be initially more sedative in the Critical Flicker Fusion test (CFF). Both drug combinations impaired short-term memory and induced retrograde amnesia to the same extent, although only the nitrazepam-ethanol treatment caused further anterograde amnesia as compared to ethanol alone. Finally, both drug-ethanol combinations exhibited equivalent hypnotic properties as assessed by the Leeds Sleep Evaluation Questionnaire (LSEQ) without any more residual effects than with ethanol alone. These results suggest neither zopiclone, nor nitrazepam potentiate the effects of ethanol at the doses used.