Merck Insomnia Drug Safer at Lower Dose, FDA Staff Says

Merck & Co.’s experimental insomnia drug, designed to turn off wakefulness rather than subdue the brain into slumber like Ambien, may only be safe at lower doses than what the company has proposed, U.S. regulators said.

Doses that Merck studied of as much as 40 milligrams of the drug suvorexant, while effective in helping the sleep deprived, may not be safe, Food and Drug Administration staff said today in a report. Lower doses may work just as well with better safety, but more information may be needed, the staff said.

“The lowest strength proposed for marketing by the sponsor is 15 mg,” staff wrote. “If a dosage strength lower than 15 mg is unavailable, we would need to consider if the drug could be marketed safely at all, if we believe that a substantial proportion of the indicated population needs a lower dose.”

Merck’s suvorexant would challenge branded and generic versions of Sanofi’s Ambien and Dainippon Sumitomo Pharma Co.’s Lunesta, the most widely used insomnia medications. Suvorexant may generate sales of $526 million in 2017 if approved, based on the average of six analysts’ estimates compiled by Bloomberg.

Advisers to the FDA will meet May 22 to recommend a proper dose, if any. The FDA is then expected to make a decision by the middle of the year, said Pamela Eisele, a spokeswoman for Whitehouse Station, New Jersey-based Merck.

Side Effects

Suvorexant blocks orexins to facilitate sleep while those for sale now work with the body’s receptors that reduce neuron activity. Merck’s approach intends to avoid next-day residual side effects. Current insomnia medications carry side effects, including suicidal thoughts and driving while not fully awake.

The staff said they were still concerned about severe residual daytime effects of suvorexant that could lead to driving while impaired. It also said there was concern about suicidal thoughts and unconscious nighttime activity.

The FDA this year said it required Sanofi and other makers of insomnia pills to cut by half the recommended doses for women after the agency found lingering effects of the drug in the morning.

Women didn’t experience the same difference in how long suvorexant stays in the body, Sable said.

Insomnia occurs in as many as 30 percent of adults, Carole Sable, project team leader and vice president of neuroscience for Merck, said in an interview. Merck is seeking to gain approval for suvorexant in two different doses to help patients fall asleep and stay asleep, Sable said.

If the FDA approves Merck’s drug, the company would still need to wait on the Drug Enforcement Administration to make a designation on restrictions for distribution based on the potential for abuse. That process could take four months or longer, Sable said. Insomnia drugs have historically been considered a Schedule IV medication, the second least restrictive of the DEA’s five classifications.