Shire attempts to block generic Intuniv

DUBLIN — Drug maker Shire has filed a patent infringement suit against Watson Pharmaceuticals and Impax Labs in response to their attempt to win approval from the Food and Drug Administration for a generic version of a Shire drug.

Shire announced that it had filed the suit in the U.S. District Court for the Northern District of California following the two generic drug makers’ filing of an approval application for guanfacine hydrochloride, a version of Shire’s Intuniv, used to treat hypertension.

Shire alleged that the filing infringes on three patents covering Intuniv, the last of which expires in July 2022, according to the FDA. Intuniv’s regulatory exclusivity period runs through September 2012.