By Daniel J. DeNoon
WebMD Health News
Reviewed by Louise Chang, MD
Nov. 28, 2012 -- Merck's experimental sleep drug suvorexant helps insomniacs fall asleep faster and stay asleep longer, early data suggest.
Later studies reported at a sleep conference last June confirmed the findings, says W. Joseph Herring, MD, PhD, Merck's executive director for clinical neuroscience. Those studies are not yet published, but they've been sent to the FDA in Merck's filing for approval of suvorexant.
"What we've seen here and confirmed in [the later studies] is that suvorexant helps people with insomnia fall asleep faster and wake less," says Herring, who led the published study. "It is effective over the long term and well tolerated."
The published study tested whether a range of doses, each given in a sleep lab to about 60 people suffering from insomnia, improved sleep better than an inactive placebo pill. Without knowing which was which, each study participant took either suvorexant or the placebo for four weeks, then switched to the other for another four weeks.
The main study measure was sleep efficiency -- that is, the percentage of an eight-hour night people slept. At the beginning of the study, participants' average sleep efficiency was 66%. After falling asleep, they woke for an average 101 minutes during the night.
"There was a range of results, but generally sleep efficiency improved 5% to 13% compared to placebo," Herring says. "We also found that patients have 21 to 37 minutes less time awake during the night."
Every Bit Helps
That may not seem like a lot. But it could mean a lot to a person suffering from insomnia, says Richard Simon Jr., MD, director of the Kathryn Severyns Dement Sleep Disorders Center in Walla Walla, Wash.
"Insomnia patients seem to feel better and function better when they get 15 to 20 minutes more sleep," Simon says. "This is an intriguing study that shows this drug does improve sleep. That is big."
What Simon finds particularly exciting is that suvorexant doesn't work like other sleeping pills. Current sleep drugs enhance brain functions that increase sleepiness. Suvorexant inhibits orexin, a hormone that acts on the brain to increase wakefulness.
Brain levels of orexin are naturally lower during the night. While Merck has focused on developing suvorexant specifically for people with insomnia, Simon suggests it might be particularly helpful for shift workers, who need to sleep during the day when orexin levels are high.
Although Merck has not disclosed the date by which the FDA must decide on suvorexant's approval, financial analysts suggest the decision is likely to come in the late summer of 2013.
The Herring study appears in the Dec. 4 issue of the journal Neurology. Simon has in the past consulted for Merck, but no longer consults or has financial ties to the company.
The study was funded and performed by Merck.
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