Watson Pharma challenges Pfizer's Pristiq patents

NEW YORK (AP) -- Watson Pharmaceuticals Inc. said Monday it is challenging a patent supporting Pfizer Inc.'s antidepressant Pristiq.

Watson said has requested marketing approval for its own low-cost generic version of Pristiq, and it said Pfizer has filed a lawsuit alleging the Watson product infringes on one of its patents. As a result of the lawsuit, Watson said the Food and Drug Administration will not approve the generic until August 2015, or until the litigation is resolved, whichever comes first.

Pfizer reported $577 million in revenue from Pristiq in 2011, and Watson cited an industry report that said U.S. sales totaled $559 million over the 12 months ended April 30. The drug was approved in February 2008 and was initially sold by Wyeth, a company Pfizer acquired in October 2009.

Watson said it may be the first company to file for approval of a generic version of Pristiq. If so, competing generics could be barred from the market for six months.

Shares of Watson Pharmaceuticals gained 70 cents to close Monday at $71.72, and were unchanged in aftermarket trading. Pfizer shares fell 26 cents to $22.47 during the regular session, and slipped 6 cents to $22.41 aftermarket.