FDA pushes Merck's suvorexant aside

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Merck's plans to take on the sleep-drug category just hit a bump. The drug maker Monday said the FDA told it that suvorexant, an orexigen receptor antagonist intended to treat insomnia, is not ready to be marketed.

Merck's aim was to get the drug approved at 15-mg and 20-mg doses, but the agency said the company should knock back the dose to around 10 mg. To advance the 10-mg dosage, Merck said, it will need to conduct "manufacturing studies."

The insomnia drug differs from others on the market by targeting a smaller part of the central nervous system and is meant to help patients stay asleep and fall asleep. The agency's complete response letter follows an advisory committee's endorsement in May. The panel had voted 13-3 for the drug, and at the time, Formulary Journal noted that the panel wasn't together when it came to the safety questions, with seven saying the drug was safe at the 20-mg dose, eight saying it was not, and two abstaining.

The FDA's rejection letter also said safety data didn't support 30-mg or 40-mg doses, according to Merck. The FDA also wants a 5-mg version, so patients taking concomitant CYP3A4 inhibitors could use the drug.

Merck said in a statement Monday that it is confident that its clinical trial data of the 10-mg dose is robust enough that it won't have to go back for additional rounds, but that it needs to explore with the agency whether clinical trials involving the 5-mg dose are needed.

The appeal of the sleepless category is simple: the CDC estimates that around 70 million Americans have some form of a sleep disorder, which includes insomnia, sleep apnea and narcolepsy, among others. The physical and mental toll is a significant one, as getting too little sleep is associated with weight gain, increased healthcare costs, and—as the CDC points out—decreased work productivity.

The knots, however, are manifold, and drugs, such as Sanofi's Ambien (zolpidem), have been associated with sleepwalking, as well as eating and driving while asleep. The FDA recently required zolpidem manufacturers to reduce the dosage in already-available products because of what can be considered a hangover effect that meant zolpidem users woke up feeling alert, yet impaired because high levels of the drug were still circulating.

Transcept/Purdue Pharma's Intermezzo honed in on a subcategory of sleeplessness—patients who can't stay asleep. But that niche approach, apparently, was not enough for commercial success, as the companies pulled the advertising campaign for the product in May.

Category competition includes Sunovion's Lunesta (eszopiclone) and Takeda's Rozerem (ramelteon). Transcept's first quarter report also notes that off-label competition of sleep drugs like Pfizer's shorter-acting Sonata (zaleplon) and Pernix's Silenor (doxepin), as well as the antidepressant trazodone, answer that same short-term consumer need.

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