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AstraZeneca PLC says it has won a judgment in a U.S. court protecting its patent on the extended release version of Seroquel, its blockbuster drug for treating bipolar disorder.

AstraZeneca said Friday that U.S. District Court in New Jersey upheld the formulation patent for Seroquel XR, which expires in 2017.

The company said the court also ruled that Anchen Pharmaceuticals, Inc., Osmotica Pharmaceutical Corp., Torrent Pharmaceuticals Ltd., Torrent Pharma Inc., Mylan Pharmaceuticals Inc. and Mylan Inc. have infringed the patent.

AstraZeneca has also been fighting legal battles to protect its patent on quetiapine, the active ingredient in Seroquel, which expires in December. Seroquel is the company’s second-largest-selling brand, accounting for 17 per cent of sales last year.