Merck & Co is facing yet another rejection of its muscle relaxant reversal agent Bridion by the FDA, seven years after the US regulator first turned it down.
The company said a scheduled FDA advisory committee meeting that had been due to review its marketing application for Bridion (sugammadex sodium) later this week has been cancelled because the agency is planning additional site inspections.
The drug – which is used to reverse the effects of muscle relaxants given during surgery, such as rocuronium or vecuronium – has previously been rejected in 2008 and 2013. In 2008 the FDA expressed concerns about hypersensitivity or allergic reactions seen with Bridion, while five years later it took issue with a study designed to investigate those effects.
Merck conducted a new hypersensitivity study and – last October 2014 – resubmitted a marketing application to the FDA and had been hoping for approval and launch later this year.
In the latest development however, the FDA has said it intends to audit sites involved in the hypersensitivity study – known as Protocol 101 – before holding an advisory committee meeting.
That means the company is now expecting a Complete Response Letter (CRL) closing out the review by scheduled action date of April 22, and a fresh red light seems the only plausible outcome.
Bridion has been on the market outside the US for several years, including in Europe, and has developed into a useful mid-tier product for the company, with sales rising 18% to $340m in 2014, driven by volume growth in all markets where it is sold.
US approval would have provided a sizeable sales hike for the drug and driven sales above the $500m level, according to analysts, but it seems US patients will still have to rely on ulcer muscle relaxant reversal agents such as neostigmine and edrophonium for some while more.
Merck maintains that Bridion provides faster and more complete reversal of neuromuscular blockade than the older drugs and has a lesser effect on heart rate.
The delay has also meant it has additional competition in the US in the form of Eclat Pharma’s Bloxiverz (neostigmine methylsulfate), an injectable formulation of the drug that was approved in 2013.
Bridion was acquired by Merck when it took over Schering-Plough in 2009.