LONDON (Reuters) - Britain's AstraZeneca said on Tuesday it was aware South Korea's Hanmi Pharmaceutical had launched a competitor to its top selling stomach-acid drug Nexium in the United States.
A U.S. court in September lifted a temporary injunction stopping Hanmi launching its esomeprazole strontium product, a close relative of Nexium. The block had been imposed because of an ongoing legal dispute over AstraZeneca's patents.
Nexium sales are declining but the heartburn and ulcer treatment remains a major seller for Britain's second-biggest drugmaker, with worldwide sales in 2012 of $3.94 billion, of which $2.27 billion was generated in the United States.
AstraZeneca said pending the outcome of an appeal, expected early next year, it could demand patent infringement damages from Hanmi's sales.
The company said it understood that Hanmi's product, which is marketed by Amneal Pharmaceuticals, was not automatically substitutable for Nexium.
It also said there was no impact on its full year 2013 financial guidance as a result of these developments.
(Reporting by Paul Sandle; editing by David Evans)