The green light comes after the US regulator had previously rejected the application for Bridion (sugammadex) on no less than three occasions - in July 2008, September 2013 and April of this year - on concerns about hypersensitivity reactions.
Last month, Merck's drawn out efforts to bring the drug to the US market finally made some headway after an FDA advisory committee voted unanimously to support Bridion's approval after deciding that the company had resolved the FDA's safety concerns.
The agency notes however that "clinicians should be aware of the possibility of a hypersensitivity reaction or anaphylaxis and should intervene as appropriate".
Bridion has been approved to reverse the effects of neuromuscular blockade induced by rocuronium bromide and vecuronium bromide, which cause temporary paralysis and are used to paralyse the vocal cords when patients require an artificial airway or breathing tube for surgery.
Neuromuscular blockers can also be used to prevent patients from moving during surgery while receiving general anaesthesia, and to prevent the body from breathing automatically when a patient has to be placed on a ventilator.
In trials, recovery time was faster overall for Bridion treatment groups compared to the comparator groups treated with drugs such as neostigmine and edrophonium, which have side effects and are known to fairly slow and unpredictable recovery from neuromuscular blockade.
Bridion becomes the first in a new class of medicines, known as selective relaxant binding agents, to be used in the US, although it has been available elsewhere for several years, bringing in sales of $340m last year from more than 60 countries. Availability in the US could push sales above the $1bn threshold, according to analysts.
Merck said it plans to launch Bridion in January and will announce Bridion's price at that time.