Efficacy and safety of eszopiclone across 6-weeks of treatment for primary insomnia

Objective: Eszopiclone is a new, single-isomer, non-benzodiazepine, cyclopyrrolone agent under investigation for the treatment of insomnia. The present study was a randomized, double-blind, multicenter, placebo-controlled trial conducted to assess the efficacy and safety of eszopiclone in adults with chronic primary insomnia. Research design and methods: Patients (n = 308) were randomized to receive placebo or eszopiclone (2 mg or 3 mg) for 44 consecutive nights, followed by 2 nights of single-blind placebo. Efficacy was evaluated with polysomnography (Nights 1, 15 and 29) and patient-reports (Nights 1, 15, 29 and 43/44). Next-day residual effects were evaluated using the Digit-Symbol Substitution Test (DSST). Results: Eszopiclone 3 mg had significantly less time to sleep onset (p less than or equal to 0.0001), more total sleep time and sleep efficiency (p less than or equal to 0.0001), better sleep maintenance (p less than or equal to 0.01), and enhanced quality and depth of sleep (p < 0.05) across the double-blind period compared with placebo. Eszopiclone 2 mg had significantly less time to sleep onset (p less than or equal to 0.001), more total sleep time (p less than or equal to 0.01) and sleep efficiency (p less than or equal to 0.001), and enhanced quality and depth of sleep (p < 0.05) compared with placebo, but did not significantly improve sleep maintenance. There was no evidence of tolerance or rebound insomnia after therapy discontinuation. Median DSST scores showed no decrement in psychomotor performance relative to baseline and did not differ from placebo in either eszopiclone group. Treatment was well tolerated; the most common adverse event related to eszopiclone was unpleasant taste. Conclusions: Patients treated with nightly eszopiclone 3 mg had better polysomnographic (through Night 29) and patient-reported measures (through Night 44) of sleep over the 6-week trial. There was no evidence of tolerance or rebound insomnia and no detrimental effects on next-day psychomotor performance using the DSST.