Merck & Co is facing yet another delay for its anaesthesia reversal drug sugammadex, as US regulators shelve an advisory meeting and announce plans for additional inspections.

The US Food and Drug Administration has cancelled Wednesday’s planned meeting of its Anaesthetic and Analgesic Drug Products Advisory Committee, so that it can carry out additional site inspections again relating to a hypersensitivity study before the drug’s resubmission is discussed.

Merck said it now expects to receive a Complete Response Letter by the FDA’s Prescription Drug User Fee Act action date on April 22, marking its third US rejection.

The second knock-back for sugammadex came in September last year, with the regulator citing concerns about operational aspects of the hypersensitivity study it previously requested. 

But the drug, which is designed to reverse the effects of deep muscle relaxation induced by the agents rocuronium and vecuronium, is already marketed in more than 50 countries around the globe.