Merck & Co Inc. said the U.S. Food and Drug Administration rejected the company's experimental insomnia drug, citing safety issues.
In a complete response letter to the company, the FDA said the safety data of the drug do not support approval, and advised that lower doses of the medicine should be made available before an approval.
The efficacy of the drug, suvorexant, was established at doses of 10 mg to 40 mg in adults, the FDA said, adding that 10 mg should be the starting dose for most patients.