Sanofi Seeks Permanent Injunction to Block Generic Ambien CR

French drugmaker sanofi-aventis has filed suit to prevent Barr Laboratories from launching its own version of the insomnia treatment Ambien.

In the complaint, filed in the U.S. District Court for the District of New Jersey, sanofi-aventis is asking the court to issue a permanent injunction against Barr from marketing generic zolpidem tartrate extended-release tablets. Sanofi-aventis claims the generic version of the drug, which is made with the active ingredient in Ambien, infringes on the brand product.

Barr submitted its abbreviated new drug application (ANDA) to the FDA last December seeking FDA approval to manufacture and market zolpidem tartrate extended-release tablets in 6.25- and 12.5-mg strengths.

Sanofi-aventis sued Barr after it learned of the ANDA. In addition to a permanent injunction, the drug company is also asking the court to issue an order that would prohibit the FDA from approving Barr's generic zolpidem tartrate extended-release products before expiration of the main patent and its pediatric exclusivity.

Sanofi holds two unexpired U.S. patents related to Ambien CR. The '531 patent expires Dec. 1, 2019, with pediatric exclusivity extending through June 1, 2020. Pediatric exclusivity for the '938 patent expires April 21, 2007.

The lawsuit marks the second U.S. legal action filed by sanofi-aventis in defense of its insomnia drug. It filed a similar patent infringement suit Feb. 5 in the U.S. District Court for the Middle District of North Carolina to block Synthon Pharmaceutical's plan to market zolpidem tartrate extended-release tablets in 6.25- and 12.5-mg doses.