Melatonin agonist tasimelteon (HETLIOZ®) improves sleep in patients with primary insomnia: A multicenter, randomized,...

Tasimelteon is a dual melatonin 1 and melatonin 2  receptor agonist. Tasimelteon is the first and only approved medicine to treat a circadian rhythm disorder. In this Phase III trial, the efficacy and safety of tasimelteon was studied in primary insomnia characterized by difficulty falling asleep.

A randomized, double-blind, placebo-controlled, multi-center study investigated 20 mg or 50 mg tasimelteon vs placebo in 322 patients with primary insomnia over a 5-week double-blind treatment interval using polysomnography(PSG) measures of sleep.

Patients underwent PSGs on Nights 1, 8, 22 and 29. Entry criteria emphasized enrollment of primary insomnia patients with a confirmed difficulty falling asleep. Subjective sleep latency was ≥ 45 minutes based on sleep history and sleep diary and, patients had a mean latency to persistent sleep (LPS) of ≥30 minutes on two consecutive screening PSG nights with no night having an LPS less than 20 minutes.

On the primary end point, the mean improvement in LPS from baseline to the average of Nights 1 and 8 was 44.9 minutes (20 mg) and 46.3 minutes (50 mg) versus 28.2 minutes (placebo) (p < 0.001). Improvements in LPS persisted through the follow-up time points (Nights 22 and 29, p < 0.01). Tasimelteon use was not associated with cognitive or mood changes, and neither rebound nor withdrawal effects were observed after discontinuation.

Tasimelteon improved sleep from the first night of treatment, and the effect continued for the duration of the study. Tasimelteon was well-tolerated with no adverse next-day residual effects observed. The results of the study strongly suggest that tasimelteon may be an effective therapeutic tool in the treatment of individuals with chronic sleep onset insomnia.