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

Background and purposeTo evaluate the clinical efficacy and safety of modified-release zolpidem (zolpidem-MR 12.5 mg) for the treatment of primary insomnia in adults.Patients and methodsTwo 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 12.5 mg 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.ResultsRelative to placebo, zolpidem-MR 12.5 mg improved sleep maintenance by significantly reducing PSG wake time after sleep onset (WASO) during the first 6 h 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.ConclusionsZolpidem-MR 12.5 mg is effective and safe in treating primary insomnia in adults and improves sleep maintenance, induction and duration of sleep.