Purdue Pharma is laying off 825 employees – 38 percent of its staff – after losing a patent case that paves the way for generic sales of a version of its painkiller OxyContin. Purdue, which had a work force of 2,154 before the layoffs, is cutting 290 of its 720 positions at its Stamford, Conn. headquarters, according to an Associated Press report. The company is also cutting over 300 sales positions nationwide and additional jobs at facilities in Ardsley, N.Y, and in Garrett Mountain and Totowa, N.J. The cuts are in response to a federal appeals court ruling in June that three Purdue Pharma patents covering OxyContin were invalid. Purdue is appealing the decision.