Phase 3 Studies of Suvorexant for Insomnia

Merck announced new data from two pivotal Phase 3 efficacy trials of suvorexant for the treatment of insomnia.

The two studies were multicenter, randomized, double-blind, placebo-controlled trials of suvorexant in patients with primary insomnia (1,021 and 1,009 treated patients in Trial 1 and Trial 2, respectively). A high and a low dose of suvorexant were studied in each trial. The high dose evaluated suvorexant 40mg in patients 18–64 years and suvorexant 30mg in patients ≥65 years, and the low dose assessed suvorexant 20mg in patients 18–64 years and suvorexant 15mg in patients ≥65 years. Patients were randomized to receive one of the suvorexant doses or placebo over a three-month period. The results reported below are for the combined primary endpoint dose of 40mg and 30mg (383 patients in Trial 1 and 387 patients in Trial 2 were treated with the high dose compared to 384 and 383 on placebo, respectively).

The endpoints for the studies included mean change from baseline for suvorexant compared to placebo in both subjective (patient-reported) and objective (polysomnographic, sleep lab-based, assessed in a subset of patients) measures of sleep onset and sleep maintenance. The subjective measures included time it took to fall asleep and total sleep time. The objective measures included time it took to fall into continuous sleep and time spent awake during the night.

In both trials, on all primary subjective measures, patients who took suvorexant fell asleep significantly faster and stayed asleep longer compared to patients taking placebo at one month and three months (P<0.003). On the objective measures, suvorexant also significantly reduced the time it took patients to fall into continuous sleep and decreased the time patients spent awake during the night at one month and three months and as early as night one (P<0.001), except for Month 3 in Trial 2, at which point the difference in time to fall into continuous sleep did not reach statistical significance.

Suvorexant targets and blocks orexins, chemical messengers that originate from the hypothalamus that maintain wakefulness. By blocking the actions of orexins, suvorexant helps to facilitate sleep. If approved, suvorexant would be the first medicine approved in a new class of medicines, called orexin receptor antagonists, for use in patients with difficulty falling or staying asleep.  

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