The sleep drug category is starting to look like a tug-of-war between drug maker and analyst expectations.
At the center is Merck's Phase III drug suvorexant. The agent focuses on orexin receptors, which are linked to wakefulness, as opposed to competitors like Lunesta and Ambien that focus on the neurotransmitter gama-aminobutyric acid, related to sleepiness.
Spurring analyst ire, Merck has offered precious few details on its sleep compound, saying in a statement that the Phase III trial results have been positive and that the company will ask the FDA for approval this year.
A November R&D presentation by Merck indicated that the orexin route was a more focused one, because orexin receptors are restricted to the hypothalamus, whereas GABA receptors are spread throughout the central nervous system. The presentation also included information about the drug's residual affects, and said Phase III trials indicated the drug did not impair driving whereas zopiclone, the active ingredient in Sanofi's Ambien, did.
“If approved, it will be a new, first-in-class treatment for patients with insomnia,” Merck R&D head Peter Kim said in the statement.
Analysts are circumspect about whether the drug's unique angle on insomnia is enough of a reason to back it.
“This particular class of insomnia drugs—orexin antagonists—has not exactly fared well. GSK and Actelion had a similar product (almorexant) in phase 3 but abruptly terminated development in early 2011 because of its side effects,” Tim Anderson of Bernstein Research wrote in a research note.
Anderson added that Merck has not been open about the drug's efficacy, safety or tolerability, making it hard to peg the drug's potential to take over or even complement a category where the market leader continues to be an off-patent product.
Generic Ambien, otherwise known as zolpidem tartrate, rang up a whopping $2.8 billion in US sales in 2011, while the leading brand in the category, 12-year-old Lunesta (eszopiclone), saw $912 million. Generic Ambien CR (zolpidem tartrate ER) took in $671.5 million while branded Ambien CR
rang up $142.3 million in revenue last year, according to data from Wolters Kluwer.
Notes Anderson, "the sleep category in general has become a more difficult commercial environment because of the widespread availability of many generic alternatives, such as market-leading Ambien. This naturally creates a cost differential between tried-and-true (and cheaper!) generics and newer therapies like surovexant."
Coming up with the next hit has been a sore spot for pharma. In addition to GlaxoSmithKline walking way from the orexin category of insomnia drugs last year, standbys like Ambien have been linked to countless stories about patients who drive, cook or consume mass amounts of food while asleep.