Impax Loses Generic Rilutek Case

A district court has ruled against Impax Laboratories in patent litigation involving Aventis Pharmaceutical’s patent for Rilutek, Impax announced last week.

The U.S. District Court for the District of Delaware ruled July 19 that Aventis’ ’814 patent related to the use of Rilutek (riluzole) for treating amyotrophic lateral sclerosis is valid, Impax said.

This decision comes after the U.S. Court of Appeals for the Federal Circuit remanded the case in November 2006, vacating the district court’s ruling of validity, Impax said.

The company had filed an abbreviated new drug application (ANDA) with the FDA in March 2001 seeking approval to market generic Rilutek 50-mg tablets. At the time there was no riluzole patent listed in the FDA’s Orange Book, according to appeals court documents.

Impax filed suit in 2002 seeking a declaration that it had not infringed on the ’814 patent. The company argued that the claims of the ’814 patent were invalid due to prior art and alleged inequitable conduct. In December 2002, the Delaware district court granted Aventis’ motion for a preliminary injunction against Impax, preventing it from marketing its product. In August 2004, the court ruled that Aventis’ patent is valid and enforceable. Impax appealed the ruling.

In its decision, the appeals court affirmed the district court’s determination that there was no inequitable conduct but ruled that the district court had erred in finding the ’814 patent valid. It vacated that ruling and sent the case back to the lower court.