Efficacy and tolerability of indiplon in transient insomnia.

Objective: The efficacy of indiplon was evaluated by polysomnography (PSG) in an experimental model of transient insomnia consisting of the first night effect combined with a 2-hour phase advance.

Methods: Healthy volunteers age 21-64 years (N=593; 62% female; mean +/- SEM) years, 32 +/- 0.39) were randomized to double-blind treatment with a single nighttime dose of indiplon (10 mg or 20 mg) or placebo. PSG assessments included latency to persistent sleep (LPS, primary endpoint) and total sleep time (TST); self-report assessments included sleep quality (SQ); next day residual effects were evaluated by the Digit Symbol Substitution Test (DSST), Symbol Copying Test (SCT), and a Visual Analog Scale of sleepiness (VAS).

Results: LPS mean (+/- SEM) values were significantly reduced on indiplon 10 mg (21.2 +/- 1.5 minutes) and indiplon 20 mg (16.8 +/- 1.1 minutes) compared to placebo (33.1 +/- 2.5 minutes; p < 0.0001 for both comparisons to placebo). TST mean (+/- SEM) values were significantly increased on indiplon 10 mg (414.5 +/- 3.9 minutes) and indiplon 20 mg (423.5 +/- 3.1 minutes) compared to placebo (402.9 +/- 3.9 minutes; p <0.005 for the 10 mg dose; p < 0.0001 for the 20 mg dose). SQ was also significantly improved on both doses. There were no differences between indiplon and placebo on next day DSST, SCT, or VAS.

Conclusions: Indiplon was effective in inducing sleep, increasing sleep duration, and improving overall sleep quality without next day residual effects in healthy volunteers in a model of transient insomnia.