A panel of experts at the US Food and Drug Administration has recommended Merck & Co's insomnia drug suvorexant when given in lower dosages but rejected the higher dose that the company was seeking.

The agency's Peripheral and Central Nervous System Drugs Advisory Committee has voted 13-3, with one abstention, that suvorexant, the first in a new class of medicines called orexin receptor antagonists, is safe for elderly patients at 15mg a day, and for non-elderly adults at 20mg. However, the panel voted 8-7, with two abstentions, that the drug is unsafe when given to the elderly patients at 30mg or non-elderly adults at 40mg.

As to whether the drug is effective, the committee voted 12 to 4 and 16 to 0, with one abstention, that the drug works in inducing and maintaining sleep. The votes were not particularly surprising given that earlier in the week, FDA staffers had said suvorexant was effective but had expressed concern about side effects including daytime drowsiness, elevated cholesterol and suicidal thinking.

This latter area was picked up by the influential US consumer group Public Citizen which gave testimony to the committee. It claimed that the now-genericised well-established sleeping aid Ambien (zolpidem) has been associated with an increased risk of car accidents, prompting an FDA alert warning patients not to drive the day after taking the drug. Suvorexant, it says, stays in the body six times longer than zolpidem, "with patients more often than not unaware of their diminished ability to drive and perform other mental tasks".

Sammy Almashat, from Public Citizen’s Health Research Group, said that "like its predecessors, suvorexant’s marginal benefit in extending overnight sleep time by a few minutes is achieved at the expense of prolonged, next-day drowsiness, with potentially fatal consequences, in addition to a litany of other serious side effects". He argued that “this drug poses far too great a risk to both patients and the general public to be on the market".

However the panellists believe there is a need for alternative insomnia treatments and the question now appears to be whether the FDA will approve a lower dose that data suggests is safer but less effective. As for Merck, Darryle Schoepp, head of neuroscience and ophthalmology research, said the votes and discussion at the meeting "bring us one step closer to providing physicians with another option to help patients struggling with insomnia.  We look forward to working with the FDA as the agency continues its review of our application".

He added that the company is "excited about the potential of suvorexant as a new and different approach to treating insomnia", and some analysts have predicted blockbuster status. All eyes are now on the FDA which is expected to give its verdict in the very near future.

Share buyback from Goldman Sachs

Meantime, Merck has also announced that it has entered into a $5 billion share repurchase agreement with Goldman Sachs.

The agreement will see the company buy back about 99.5 million shares using proceeds from the company’s recently-concluded debt offering. The move is part of Merck’s previously-announced $15 billion share repurchase programme.

The deal "demonstrates our commitment to delivering increased value to shareholders in the short term, while continuing to invest in the important opportunities that will drive our long-term growth,” said chief executive Kenneth Frazier.