Chronic administration of zopiclone and nitrazepam in the treatment of insomnia.

The hypnotic effects of 7.5 mg zopiclone, as well as its unwanted and residual effects, were compared with those of 5 mg nitrazepam in a double-blind, randomized, multicenter, parallel group study. After an initial, 7-day, placebo wash-out period, insomniac out-patients under the care of general practitioners received either 7.5 mg zopiclone or 5 mg nitrazepam for 6 weeks. Everyday, the patients filled in a diary (analogue scales for sleep parameters and condition during daytime); a sleep questionnaire was filled in at baseline and at the end of active treatment period; every 2 weeks, a somatic complaint check-list inventory and a mood rating scale were filled in and psychomotor tests performed; and at the end of the study, a global evaluation of efficacy and acceptability was given by the investigator. Clinical laboratory tests were performed before and after the active treatment period. From the diary, sleep onset latency, as well as sleep quality, were similarly improved by both drugs throughout the whole study. From the sleep questionnaire, all sleep parameters measured were improved at the end of the 6-week treatment period in both groups. No statistical differences in the various psychomotor tests were observed between the two treatment groups, and a significant improvement in the working ability of patients was noted with both drugs. Some significant differences were observed in the mood rating scale and the somatic complaint check list, probably related to differences in pharmacokinetics of the two drugs.

Interactions and comparative effects of zopiclone, diazepam and lorazepam on psychomotor performance and on elimination pharmacokinetics in healthy volunteers.

A randomised, placebo-controlled, double blind single-dose cross-over study was arranged to investigate possible interactions between zopiclone (7.5 mg) and two widely used benzodiazepine (BZD) anxiolytics diazepam (5 mg) and lorazepam (1 mg) during the elimination phase of drugs. Psychomotor performance was tested before and 1, 6, 8, 12 and 24 hr after the drug administration. Simultaneously, blood samples were drawn for determination of plasma drug concentrations. The elimination of each compound was not altered by coadministration of other drugs. As expected, one hour after drug ingestion, psychomotor performance was impaired. The coadministration of drugs increased the effect. During the elimination phase, 6 and 8 hr after the drug intake, only zopiclone and lorazepam in combination slightly impaired performance as compared with the pretreatment levels, but there was no difference as compared with placebo. Adverse events after active treatments were not significantly different from those after placebo. At the recommended dose of 7.5 mg, zopiclone does not alter the elimination pharmacokinetics of the BZD anxiolytics diazepam (5mg) and lorazepam (1 mg), and neither is the elimination of zopiclone affected by these BZDs. Due to the rapid elimination of zopiclone, the increase in sedation seen after concurrent administration with BZDs is of short duration.