Merck submits novel sleep drug to FDA

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As expected, Merck made a regulatory filing for suvorexant, a novel insomnia drug angling to enter a multi-billion-dollar category rife with cheap generics.

The drug blocks orexin receptors to help patients fall asleep more quickly and to stay asleep. As such, its mechanism of action (MOA) differs from the non-benzodiazepines like Sanofi's Ambien, which leads the market as a generic, as well as Sunovion's Lunesta and King's Sonota, all of which work by stimulating the neurochemical GABA.

With tried-and-true generics available, a new insomnia brand faces a difficult competitive landscape, analysts have said. Phase III efficacy trials showed patients taking the drug fell asleep about 10 minutes faster than placebo, and stayed asleep about 20 minutes longer. Is that enough to give suvorexant a marketing edge?

Merck's not banking on it. The company powered the sleep drug's development program to also highlight its side-effect profile, including a 12-month study involving 781 patients, which Merck says is the longest placebo-controlled trial of a sleep drug.

The most common adverse events seen were sleepiness, inflammation of the nasal passages, fatigue, upper respiratory tract infection and dry mouth. The list does not include effects like unknowingly driving a car or binge eating—cases that have been associated with Ambien (zolpidem).

The year-long trial was followed by a two-month discontinuation phase designed to assess safety and longer-term efficacy and the impact of stopping treatment. Adverse events were similar to placebo. Two three-month trials were conducted, as well, again showing suvorexant was well tolerated.

The company said it also conducted two next-day, placebo-controlled driving studies to offer an assessment of residual effects following evening use of suvorexant. Data from one of these studies, read out at June's SLEEP 2012 meeting, showed the drug was not associated with next-day residual impairment as assessed by highway driving performance, balance and cognitive tests in the elderly.

Zopiclone, another non-benzodiazepine, was used as a control on days one and eight. Zopiclone “impaired driving performance to a clinically meaningful extent,” according to an abstract of the study.

Results of the second of the two next-day trials have been submitted to a medical meeting and have yet to be made public, a spokesperson told MM&M.

As far as an FDA decision on suvorexant, the company will most likely need to hibernate until 2014. Merck said it anticipates a standard review, which is 10-12 months, and that the drug will be evaluated by the Controlled Substance Staff of the FDA, which could take an added four months, or longer, following an FDA decision on approval.

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