FDA denies approval of insomnia drug at current dosage

The FDA decided not to approve suvorexant, a drug under investigation for the treatment of insomnia, deeming the high dosages unsafe, according to a press release from the drug manufacturer.

Suvorexant (Merck) would be the first in a new class of orexin receptor antagonist medicines, yet the 30 and 40 mg dosages were deemed too high by the FDA in a Complete Response Letter.

In May, the Peripheral and Central Nervous System Advisory Committee reported that several safety issues were found in a study of suvorexant, including driving impairment, daytime somnolence, unconscious and intense nighttime activity, suicidal ideation and narcolepsy-like syndrome.

“Suvorexant is effective, but not safe at the higher doses mainly studied,” the committee wrote in their presentation.

According to the Merck press release, the FDA advised that 10 mg be the starting dose, with 15 and 20 mg doses available for patients who did not see results with 10 mg. A starting dosage of 5 mg was recommended for patients taking concomitant moderate CYP3A4 inhibitors.

“The lowest doses have similar efficacy and better safety, but because studied in fewer patients, rates of less common but potentially serious [adverse events] are not well understood,” the FDA report said.

“We will evaluate the requests outlined in the Complete Response Letter, and expect thereafter to work expeditiously with the FDA to make suvorexant available as a new treatment option for patients suffering from insomnia,” Roger M. Perlmutter, MD, PhD, president of Merck Research Laboratories, said in the press release.