US regulators have now issued a green light for Impax Laboratories’ Parkinson’s disease drug Rytary more than two years after rejecting it on manufacturing issues.

The US Food and Drug Administration has green-lighted Rytary - an extended-release form of carbidopa-levodopa - for the treatment of Parkinson's disease, post-encephalitic parkinsonism, and parkinsonism post carbon monoxide and/or manganese intoxication.

Rytary, which should be on pharmacy shelves in the US next month, “is designed to address one of the most significant unmet needs for patients living with Parkinson's disease, which is to reduce the amount of time during the day when their symptoms are not adequately controlled,” said Impax chief executive Fred Wilkinson.

But despite solid clinical data its path to market has less than smooth. In early 2013, the FDA turned down the drug and ordered a re-inspection of its manufacturing site, and continuing regulatory issues prompted GlaxoSmithKline to hand back rights to Impax later that year.

Rytary has now become the first branded medicine internally developed by Impax and approved for commercialisation, and the FDA nod will be particularly sweet given the firm’s rocky run of late, ending in a swathe of job cuts last year.