Zopiclone and nitrazepam: a multicenter placebo controlled comparative study of efficacy and tolerance in insomniac patients in general practice.

The efficacy and tolerance of zopiclone were compared with nitrazepam and placebo in a multicenter double-blind parallel-group study in insomniac patients. Following a 7-day placebo washout period, 99 patients (age range 20 to 69 years) received oral capsules of 7.5 mg zopiclone or 5 mg nitrazepam or placebo for 2 weeks. During the fourth week all patients received placebo treatment. Sleep assessments by the patients showed that, compared with placebo, zopiclone and nitrazepam improved all sleep measures of efficacy from the first night and that effectiveness was maintained throughout treatment. The physicians global assessment of efficacy also favored zopiclone and nitrazepam over placebo treatment. Subjective morning drowsiness during treatment was significantly less for zopiclone than for either nitrazepam or placebo and represents a clear advantage for ambulatory patients. No rebound insomnia was evident during a 7 day post-treatment withdrawal period for either zopiclone or nitrazepam. Tolerance was good for all treatments.