Watson challenges Exelon patent; wins Seasonique appeal; launches generic Kadian

There was an active day for US generics drugmaker Watson Pharmaceuticals (NYSE: WPI), first, confirming that its subsidiary, Watson Laboratories, had filed an Abbreviated New Drug Application with the US Food and Drug Administration seeking approval to market rivastigmine transdermal system patches, 4.6mg/24hr and 9.5mg/24hr, a generic version of Swiss major Novartis' Exelon Patch, which is used to treat people with mild to moderate dementia associated with Alzheimer's or Parkinson's disease.

Novartis filed suit against Watson on November 9, 2011 in the US District Court for the District of Delaware seeking to prevent Watson from commercializing its product prior to the expiration of US Patent Nos. 5,602,176; 6,316,023 and 6,335,031. 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 that Novartis 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 Exelon Patch and, should its ANDA be approved, may be entitled to 180 days of generic market exclusivity. For the 12 months ending September 30, 2011, Exelon had total US sales of approximately $424 million according to IMS Health data.