Generic Drug Makers Sue to Block Patent on Anxiety Treatment

Generic drug makers Watson Pharmaceuticals Inc. and Mylan Laboratories Inc. filed separate lawsuits Thursday to block a new patent on Bristol-Myers Squibb Co.’s anxiety drug, as the patent would mean delays on generic versions of the drug.

Corona-based Watson and Mylan, based in Pittsburgh, had expected Food and Drug Administration approval last week on different dosages of buspirone, a generic equivalent of Bristol-Myers’ BuSpar. Instead, Bristol-Myers announced Nov. 21 that it had received a patent that would extend its exclusive right to sell the treatment.

The new patent means Bristol-Myers could file an infringement suit if the generic drug makers tried to introduce a generic version of BuSpar, which would delay approval of the generic by as much as 30 months. BuSpar had third-quarter sales of $175 million.

Watson’s suit, filed in U.S. District Court in Maryland, seeks to keep the FDA from listing the patent and asks the court to order the FDA to approve its buspirone treatment. Mylan asks for a judge to find the new patent invalid, according to court documents. Mylan filed its suit in U.S. District Court in West Virginia.

In New York Stock Exchange trading on a day of a broad market sell-off, shares of Watson fell $3.69, or 7.4%, to close at $46; Bristol-Myers fell $2.88 to close at $69.31; and Mylan rose 81 cents to close at $23.94.