Merck Insomnia Therapy Gets Complete Response Letter

Pharmaceutical giant Merck is bound to lose a little sleep over this. The FDA sent it a complete response letter regarding its new drug application for an investigational medicine for the treatment of insomnia, suvorexant.

The CRL said the pharma's idea to start elderly patients on a 15 mg regimen and move them up to 30 mg if necessary was not safe. Nor was Merck's idea to start non-elderly patients at 20 mg and kick them up to 40 mg if necessary. Instead, the regulatory agency said it was best to start most patients off at 10 mg and, if it was well tolerated, they could move up to 15 mg or 20 mg. Before Merck could move forward, however, it would have to have a 10 mg dosage already in hand.

Merck said it doesn't believe it would need to do additional clinical studies for the 10 mg dosage of suvorexant, but would need to do manufacturing studies. Analysts have speculated it might cause a delay of a year or more to conduct such studies. They estimate the drug could have sales of $700 million annually by 2018.

If approved, suvorexant would be the first in a new class of medicines, called orexin receptor antagonists, for use in patients with insomnia. Orexins are neurotransmitters in the brain that help to keep a person awake and suvorexant blocks their action, allowing them to go to sleep.

A 5 mg dose of suvorexant was also recommended by the FDA for patients taking concomitant moderate CYP3A4 inhibitors. Merck will be discussing with the regulatory body whether additional studies will be required to support the lower dosage.

Merck stock closed down $0.13 today at $46.32 per share.

The article Merck Insomnia Therapy Gets Complete Response Letter originally appeared on Fool.com.

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