Having sued the Food and Drug Administration in the summer, Watson Pharmaceuticals has launched its generic versions of Takeda's blockbuster diabetes drug Actos in the USA which have received the agency's final approval.

Watson has begun shipping the product immediately, some two months after Mylan, Teva and Ranbaxy started selling copycat versions of Actos (pioglitazone) across the pond. Those three have been sharing 180-day exclusivity for the drug, sales of which were around $2.7 billion for the year ended August 31, according to IMS data.

That decision angered Watson which filed suit against the FDA in August challenging the agency's decision regarding the firm's belief that it was entitled to shared exclusivity. Mylan subsequently intervened as a defendant in the action but last week, a US District Court for the District of Columbia ruled in favour of Watson and ordered the FDA to approve Watson's abbreviated New Drug Application.

Mylan has appealed the judgment but its motion for a stay of the judgment pending a decision was denied by the US Court of Appeals for the DC Circuit. Under the terms of a previous settlement, Takeda licensed the US patents to Watson, allowing the latter to start marketing generic Actos from August 17, 2012.