AstraZeneca Plc (AZN:US) lost an appeals court ruling today that clears sales by Korea’s Hanmi (128940) Pharm Co. of a competing copy of the heartburn treatment Nexium.
AstraZeneca’s patent on the drug is limited to a specifically named salt, the U.S. Court of Appeals for the Federal Circuit in Washington said in an opinion posted on its website. AstraZeneca had conceded that Hanmi’s version wouldn’t infringe the patent if the appeals court ruled in that way.
Nexium is AstraZeneca’s second-biggest product, with sales of $918 million in the third quarter. Hanmi and partner Amneal Pharmaceuticals LLC have their own version of esomeprazole, the active ingredient in Nexium. Pharmacists can’t automatically swap out the Hanmi version for Nexium as they would if a generic drug were on the market, London-based AstraZeneca said in a Dec. 17 statement.
Hanmi had been banned from selling the drug pending the appeal, although the Federal Circuit lifted that order and Hanmi entered the market earlier this week.
AstraZeneca researchers found that certain types of salt worked better, and thus limited the patent to a specific class of salts, the three-judge panel ruled. Nexium is the magnesium salt of esomeprazole, while Hanmi’s version is the strontium salt.
The case is AstraZeneca AB. V. Hanmi USA, 13-1490, U.S. Court of Appeals for the Federal Circuit (Washington).
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