Efficacy and tolerability of indiplon in transient insomnia

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.

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).

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.

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.