Sanofi-Aventis filed lawsuit against Sandoz to block Zolpidem Tartrate CR generic

Sanofi-Aventis filed a lawsuit on Friday against Sandoz on Ambien (Zolpidem Tartrate) CR. Sandoz recently filed an ANDA with the USFDA to market a generic extended-release tablet containing zolpidem tartrate, the active ingredient in Ambien, before Aventis patent on the Zolpidem, US6514531, expires, Sanofi says in a complaint filed in the U.S. District Court for the District of New Jersey.The '531 patent, issued to Sanofi in 2003, describes a “controlled-release dosage forms of zolpidem or salts thereof adapted to release zolpidem over a predetermined time period.” Sandoz certified in its ANDA that the '531 patent is invalid, according to Sanofi's complaint. Sanofi has requested the court to enjoin Sandoz from selling a generic version of Ambien until the '531 patent expires and to award monetary damages for any other acts of infringement it might find.Last June, the company sued Mutual Pharma, United Research Lab and their parent company Pharmaceutical Holdings Corp., which had also filed an ANDA to make generic versions of Ambien. Those suits are still pending in the District of New Jersey. In addition, Sanofi filed suit in February 2007 against Dutch pharmaceutical company Synthon Holding BV over an ANDA Synthon submitted in a bid for FDA approval to market generic Ambien in the U.S. As in the suits against Sandoz and Mutual, Sanofi asserted the '531 patent in its suit against Synthon. Ambien, which was approved for sale in the United States in the early 1990s, is one of Sanofi's biggest sellers, generating $1.9 billion in sales during the first nine months of 2006.