The U.S. Food and Drug Administration has denied a new drug application submitted by Merck for suvorexant, the New York Times reported Monday.  Suvorexant is an orexin receptor antagonist with a proposed indication for insomnia characterized by difficulties with sleep onset and/or maintenance.  According to a Merck statement, the FDA determined that the safety data do not support the approval of the proposed suvorexant doses of 30 mg and 40 mg.

The FDA indicated that the starting dose for most patients should be 10 mg, which must be available before suvorexant can be approved.  A 5 mg dose would be necessary for some patients who are already taking other medications.  Merck noted that manufacturing studies will be required to advance the 10 mg form of the drug.  Currently, Merck is uncertain if additional studies will be required to support the 5 mg dose.