Court rules against Watson on Naprelan patent

Watson Pharmaceuticals says that the US District Court for the Southern District of Florida has ruled that its naproxen sodium ER tablets, the generic version of Naprelan, infringes Irish drugmaker Elan's US Patent No 5,637,320. The product had sales of around $4.0 million in the 12 months to June 2008, comppared to around $27.0 million in 2002.

The action, Elan Corp Plc versus Andrx Pharmaceuticals (which Watson has acquired), was initially brought by Elan in October 1998 following Andrx' filing of a paragraph IV Abbreviated New Drug Application for its product. In March 2002, the District Court ruled that Elan's '320 Patent was invalid. Subsequently, in May 2004, the US Court of Appeals for the Federal Circuit reversed the District Court's finding of invalidity and remanded the case for further proceedings. In January 2005, Elan filed a related case against Andrx in the US District Court for the Southern District of Florida alleging that Andrx' Naproxen Sodium ER tablets infringe the '320 Patent, and seeking damages for willful infringement. In late 2005, the parties completed briefing the District Court on the validity of the patent and whether Andrx' product infringesit. The matter has been under submission to the District Court since late 2005.

In this latest ruling, the District Court held that Andrx' naproxen sodium ER tablets infringe the '320 Patent and that the company infringement was willful. Watson says it intends to appeal the latest ruling.