Schering-Plough has suffered a major blow with the news that US regulators have rejected its anaesthesia compound sugammadex, just months after being recommended for approval.

The US Food and Drug Administration has issued a ‘not-approvable’ letter for Bridion (sugammadex), an injection for the reversal of muscle relaxation during general anaesthesia. Earlier in the week, it had been approved by regulators in Europe and their counterparts across the pond have expressed concern about hypersensitivity and allergic reactions.

Tom Koestler, president at the Schering Plough Research Institute said that “we are surprised and disappointed with this action, especially given that sugammadex received a unanimous recommendation for approval by the FDA Advisory Committee on Anesthetics and Life Support in March”. Noting that the agency’s letter did not relate to any issues related to the efficacy of the drug, Dr Koestler added that Bridion “represents the first major pharmaceutical innovation in the field of anaesthesia in two decades…we remain committed to bringing this important medical advance to those who are waiting for it in the USA”.

Bridion was specifically designed to reverse “within minutes both moderate and deep muscle relaxation” induced by rocuronium or vecuronium. This may help improve surgical conditions “in the millions of procedures where these agents are used”, the firm claimed when the European approval came through last week. Indeed Dr Koestler had said that the European Commission green light for sugammadex, the first major approval of a product to come out of its 11 billion-euro acquisition of Organon BioSciences from the Dutch firm Akzo Nobel, “further validates the value of our combination, which…is already making a positive contribution to our business”.

That assumption is now being called into question after the FDA decision seeing as how Bridion was supposed to be one of the jewels in Organon’s crown. Analysts had predicted that it would be a blockbuster that would help S-P reduce its dependence on the controversial cholesterol drugs Vytorin (ezetimibe and simvastatin) and Zetia (ezetimibe), but that now seems some way off.

Investors were highly disappointed and S-P’s shares closed down 3.2% at $20.41 though the share price had fallen by as much as 9% once the agency’s not approvable letter was revealed.