Somaxon Pharmaceuticals, Inc, San Diego, announced positive results from the company’s Phase 3 clinical trial evaluating SILENOR™ (doxepin HCl) in adults with transient insomnia. SILENOR demonstrated statistically significant improvements compared to placebo (p<0.0001) in the primary endpoint of this trial, Latency to Persistent Sleep (LPS), a measure of sleep onset. SILENOR also produced statistically significant improvements relative to placebo in multiple secondary endpoints, including measures of both sleep onset and sleep maintenance.

This Phase 3 trial was a randomized, double-blind, placebo-controlled, multi-center, parallel group study that enrolled 565 adults in a sleep laboratory setting using a phase-advance, first night assessment model of induced transient insomnia. Efficacy assessments evaluated both objective PSG (polysomnography) and subjective measures of sleep. Results demonstrated that 6mg of SILENOR was effective at inducing sleep and maintaining sleep throughout the night.

SILENOR achieved statistically significant results in multiple endpoints including:
• Latency to Persistent Sleep (LPS): Improvement compared with placebo of 13 minutes (p<0.0001)
• Latency to Sleep Onset (LSO), a subjective measure: Improvement compared with placebo of 16 minutes (p<0.0001)
• Wake After Sleep Onset (WASO): Improvement compared with placebo of 40 minutes (p<0.0001)
• Total Sleep Time (TST): Improvement compared with placebo of 51 minutes (p<0.0001)

Additionally, SILENOR achieved statistically significant results compared to placebo in Sleep Efficiency (SE) for the entire night and in each third of the night, as well as in subjective measures of sleep maintenance (sWASO, sTST) and Sleep Quality (SQ).

The study also demonstrated that SILENOR was well tolerated. The incidence of adverse events was low and comparable to placebo. There were no reports of amnesia, memory impairment, or anticholinergic effects, and there were no clinically meaningful effects on measures of next day impairment.

The company expects results from its remaining two Phase 3 clinical trials for SILENOR by the end of this year.