Watson confirms patent challenges for Xopenox HFA and Epiduo Gel

US generics drugmaker Watson Pharmaceuticals NYSE: WPI) has confirmed that its subsidiary, Watson Laboratories filed an Abbreviated New Drug Application) with the US Food and Drug Administration seeking approval to market levalbuterol tartrate inhalation aerosol, a generic version of Sunovion Pharmaceuticals, Xopenox HFA which is indicated for the treatment or prevention of bronchospasm in adults, adolescents, and children four years of age and older with reversible obstructive airway disease.

Sunovion, a subsidiary of Japanese drug major Dainippon Sumitomo Pharma (TYO: 4523), filed suit against Watson on July 27 in the US District Court for the District of Delaware seeking to prevent Watson from commercializing its ANDA product prior to the expiration of certain US patents. The law suit was filed under the provisions of the Hatch-Waxman Act, resulting in a stay of final FDA approval of Watson's ANDA for up to 30 months from the date the plaintiffs received notice of Watson's ANDA filing or until final resolution of the matter before the court, whichever occurs sooner, subject to any other exclusivities.

Based on available information, Watson believes it may be a "first applicant" to file an ANDA for the generic version of Xopenox HFA and, should its ANDA be approved, may be entitled to 180 days of generic market exclusivity. For the 12 months ending March 31, 2012, Xopenox HFA had total U.S. sales of approximately $148 million, according to IMS Health data quoted by Watson