Efficacy and safety of zolpidem-MR: a double-blind, placebo-controlled study in adults with primary insomnia.

To evaluate the clinical efficacy and safety of modified-release zolpidem (zolpidem-MR 12.5mg) for the treatment of primary insomnia in adults. Two hundred and twelve (123 women, 89 men; mean age 44.3+/-SD 3.0 years), Diagnostic and Statistical Manual of Mental Disorders--4th Edition (DSM-IV)-defined primary insomnia patients were randomized in a double-blind, placebo-controlled, parallel-group study. The study was completed by 192 patients. Patients received 3 weeks of nightly treatment with either zolpidem-MR 12.5mg or placebo, preceded and followed by two nights of single-blind placebo. The main outcome measures were mean polysomnographic (PSG) sleep parameters of nights 1/2 and nights 15/16 of double-blind treatment and daily subjective sleep estimates from sleep questionnaires to assess efficacy, and PSG parameters of nights 22 and 23 of single-blind placebo substitution to assess the effect of drug discontinuation. Relative to placebo, zolpidem-MR 12.5mg improved sleep maintenance by significantly reducing PSG wake time after sleep onset (WASO) during the first 6h of sleep as well as the number of awakenings. Consistent with the effects of standard zolpidem, zolpidem-MR also significantly reduced latency to persistent sleep, and significantly increased sleep efficiency, both at the beginning and after 2 weeks of double-blind treatment. There was no evidence of next-day residual effects as measured objectively by psychometric tests. Rebound insomnia on the first night after abrupt discontinuation resolved the following night. Overall, zolpidem-MR was well tolerated. Zolpidem-MR 12.5mg is effective and safe in treating primary insomnia in adults and improves sleep maintenance, induction and duration of sleep.