Study objective: Indiplon is a nonbenzodiazepine GABA potentiator, which exhibits pharmacologic selectivity for GABA(A) receptors containing the alpha1 subunit. The aim of the present study was to evaluate the efficacy and safety of a 15-mg nightly dose of modified-release indiplon tablets in elderly patients with primary insomnia characterized by sleep-maintenance difficulties.
Methods: Two hundred twenty-nine elderly patients, aged 65 to 85 years, who met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for primary insomnia were randomly assigned to 2 weeks of nightly treatment with either indiplon, 15 mg, or placebo in a double-blind, parallel-group design. Daily sleep diaries were completed to collect patient reports of subjective total sleep time, wake time after sleep onset, number of awakenings after sleep-onset, latency to sleep onset, and sleep quality. Patient global impression ratings of various parameters of sleep were assessed on a weekly basis.
Results: The least square mean total sleep time was significantly improved with indiplon versus placebo at week 1 (377 +/- 4 min vs. 328 +/- 4 min; p < .0001) and week 2 (373 +/- 5 min vs. 337 +/- 5 min; p < .0001). Indiplon also significantly improved subjective wake after sleep onset, subjective number of awakenings after sleep onset, subjective sleep-onset latency, sleep quality, and patient global impression ratings of sleep at both weeks 1 and 2. The number and severity of adverse events and rates of discontinuation due to adverse effects were comparable in the indiplon and placebo groups.
Conclusions: In elderly patients with primary insomnia characterized by sleep-maintenance difficulty, indiplon, 15 mg, was well tolerated and significantly improved all patient-reported measures of sleep during 2 weeks of treatment.