Merck's insomnia drug Suvorexant may not be approved yet by the US Food and Drug Administration (FDA), but if it ever is, its path to market will probably be even shorter thanks to a decision made by the US Drug Enforcement Administration (DEA) this week.
Suvorexant is an investigational orexin receptor antagonist intended to treat insomnia in patients. While its sponsor, Merck, has already completed several Phase III trials in support of the drug's marketing application, it was rejected by FDA regulators in late 2013 after members of its Peripheral and Central Nervous System Drugs Advisory Committee raised questions about the doses for which the company was seeking approval.
Merck had been seeking a 15 mg dose for elderly patients and a 20 mg dose for non-elderly patients, but the advisory committee said there was little evidence to support the higher doses of the drug, and pushed instead for a 10 mg dose to be approved, leading to a bizarre situation in which Merck was arguing against the approval of its own drug at that dose level.
Based on concerns raised by the committee, FDA ultimately issued a complete response letter for the drug, stating that while the 15 and 20 mg doses could be approved for select populations, it would need to see more data before it would approve the 10 mg dose in the patient population originally sought after by Merck.
Good News for Merck
While Merck pursues that data, it received what could be construed as positive news from DEA on 13 February 2014.
The agency announced that it had proposed classifying Suvorexant as a Schedule IV drug under the Controlled Substances Act (CSA) based on FDA's recommendation. FDA's eight-factor analysis had determined that the drug, which works by reducing wakefulness, could be abused similar to other sedatives such as Ambien (zolpidem), another Schedule IV drug.
Under the CSA's rating system, Schedule IV drugs are those with a low but present potential for abuse, a clear medical use and minimal health effects associated with abuse of the drug. The classification means that refills on the drug will be limited so as to limit abuse, and the drug will be subject to tighter labeling, registration, packaging and other requirements.
So why is that a good thing?
Consider the recent case of Arena Pharmaceutical's weight loss pill Belviq (lorcaserin), also a Schedule IV drug. The drug spent nearly a year in DEA's regulatory "black hole" after receiving FDA approval, during which time Arena was unable to market the drug while DEA determined how to schedule it.
Without receiving DEA approval, it wasn't allowed on the market.
But the fact that DEA has already proposed a scheduling classification for Suvorexant, as well as a likely abuse analog in Ambien, means that Suvorexant-should it ever receive FDA approval-will likely not have to wait as long before actually being allowed to market itself.
Comments on DEA's proposed scheduling are due to the agency by 17 March 2014.