WHITEHOUSE STATION, N.J.--(BUSINESS WIRE)--

Merck (MRK), known as MSD outside the United States and Canada, today announced new data for suvorexant, the investigational medicine Merck is developing for the treatment of insomnia. The new data are from one of the longest, continuously-dosed, placebo-controlled trials of a sleep medication ever conducted. This 12-month study was designed to assess the safety of suvorexant, while also evaluating its longer term efficacy. Merck presented new results from a two-month discontinuation phase that followed the 12-month study at the 21st Congress of the European Sleep Research Society (ESRS).

The methods used in this study allowed us to understand what happened when patients who had been taking suvorexant every night for a year were immediately switched to placebo, because what happens when patients stop taking a sleep medication is a key concern for both patients and healthcare professionals, said James K. Walsh, Ph.D., executive director and senior scientist, Sleep Medicine and Research Center, St. Luke's Hospital, and visiting professor, Department of Psychiatry, Stanford University School of Medicine. "We found that the patients who had been taking suvorexant for 12 months and were switched to placebo saw their insomnia return, but clinically meaningful withdrawal symptoms and rebound insomnia did not emerge. We also obtained efficacy data from patients who continued to take suvorexant through 14 months."

Specifically, results from the two-month discontinuation phase showed that, after daily use of a consistent dose of suvorexant for one year, patients who stopped taking the medicine experienced a return of their sleeping difficulties to levels similar to those reported by patients who received placebo over the course of the trial. Patients who continued to receive suvorexant for the additional two months experienced mean improvements in their ability to fall asleep and stay asleep that were consistent with those seen over the first 12 months compared to placebo. Adverse experiences reported in the two-month discontinuation phase were generally consistent with those reported during the 12-month study.

Merck researchers developed suvorexant to target and block orexins, chemical messengers that originate from the hypothalamus (an important sleep center in the brain) and help keep you awake. By blocking the actions of orexins, suvorexant helps facilitate sleep. Merck plans to file a New Drug Application (NDA) for suvorexant with the U.S. Food and Drug Administration (FDA) in 2012. If approved, suvorexant would be the first in a new class of medicines, called orexin receptor antagonists, for use in patients with difficulty falling or staying asleep. Merck anticipates that suvorexant will be evaluated by the Controlled Substance Staff of the FDA.

Suvorexant represents a new and different approach to treating insomnia, an area of significant unmet need, said Darryle D. Schoepp, Ph.D., senior vice president and head of Neuroscience and Ophthalmology franchise, Merck Research Laboratories. We are enthusiastic about the results of this long-term study, which provide important insights into suvorexant and the chronic nature of insomnia. Merck is continuing with plans to seek approval for suvorexant in the U.S. and in other countries around the world.

Study evaluated safety and efficacy of suvorexant in 12-month study and two-month discontinuation phase

In Mercks long-term, double-blind, Phase III trial, 781 patients with primary insomnia were randomized to receive a consistent dose of suvorexant (40 mg per night in patients 18-64 years of age or 30 mg per night in patients 65 years and older) (n=521) or placebo (n=258) over a 12-month treatment period. Patients who completed the entire 12-month study (n=484) continued into a two-month, randomized, placebo-controlled, parallel-group discontinuation phase to evaluate both the effects of stopping suvorexant and switching to placebo (n=166), as well as the efficacy of continued suvorexant treatment at months 13 and 14 (n=156). Patients who took placebo during the initial 12-month study continued to take placebo (n=162).

There were no primary efficacy endpoints in the 12-month study, which had the main objective to evaluate the safety and tolerability of suvorexant for up to 12 months of treatment. Secondary efficacy endpoints in the 12-month study included mean change from baseline for suvorexant compared to placebo in patient-reported measures of time to fall asleep and total sleep time during the first month of treatment. Other efficacy endpoints measured at all other time points in the 12-month study and two-month discontinuation phase were exploratory, including assessment of time to return of sleeping difficulties.

Safety and tolerability were assessed by adverse event (AE) reports, laboratory values, electrocardiograms, physical exams, vital signs, withdrawal symptoms as evaluated by the Tyrer Benzodiazepine Withdrawal Questionnaire (a questionnaire used to record the symptoms patients experience when they stop taking medication) and patient-reported rebound insomnia (a worsening of sleep measures compared with pre-treatment levels). The primary time period for safety analyses in this study was the 12-month treatment phase. Safety endpoints in the discontinuation phase were secondary, with focus on evaluation of rebound and withdrawal effects.

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Merck Announces New Phase III Data for Suvorexant, an Investigational Insomnia Medicine