Suvorexant, an experimental drug from Merck & Co., is being studied in people with insomnia. This medication is not currently approved for commercial use and has only been available in final-stage clinical trials.

Suvorexant is in a new group of drugs called Dual Orexin Receptor Antagonists (DORAs). Orexin, a natural chemical responsible for regulating the brain's sleep-wake process, is produced by neurons in the part of the brain called the hypothalamus. DORAs, like suvorexant, make transitions from wake to sleep easier by blocking orexin receptors. In essence, this medication turns off wakefulness, instead of calming the brain to sleep, as seen with other insomnia medications.

In 2 large clinical trials, each with more than 1,000 patients, suvorexant 10 mg, 20 mg, and 40 mg was tested against placebo. Suvorexant reduced the time it took patients to fall asleep by 25.7 minutes, and patients were able to sleep 60.3 minutes longer than before treatment.

On May 20, 2013 and FDA advisory committee warned that while the insomnia drug appears to be effective at helping patients sleep, it also had dangerous side effects including daytime drowsiness and suicidal thinking, particularly when taken at higher doses.

Merck has proposed a suvorexant starting dose of 20 mg (15 mg for seniors), with gradual increases to 40 mg (30 mg for seniors). The FDA advisory committee may seek to eliminate the higher suvorexant doses as tested by Merck.

On Wednesday, May 22, 2013 a panel was convened to help the FDA decide whether to approve Suvorexant. The panel voted 13 to 3 that the drug could be used safely at the 15 and 20 milligram doses. It voted 8-7 that the drug is not safe at 30 and 40 milligrams. The panel also voted against requiring Merck to conduct additional trials. The FDA usually follows the advice of its advisory panels, although it is not required to.