Impax Labs sued by Daiichi Sankyo and Genzyme after challenging Welchol patent in USA

US generic drugmaker Impax Laboratories confirmed that it has initiated a challenge to patents listed by Japanese drug firm Daiichi Sankyo in connection with its cholesterol-lowering product Welchol (colesevelam HCl) tablets, 625mg, including one that US biotech major Genzyme inherited when it acquired GelTex Pharmaceuticals in 2000. The patents are claimed to expire in 2014 and 2015.

Impax filed its Abbreviated New Drug Application containing a paragraph IV certification for a generic version of Welchol with the US Food & Drug Administration. Following receipt of the notice from the FDA that its ANDA had been accepted for filing, Impax says it notified the New Drug Application holder and patent owners of its paragraph IV certification.

On January 14, Daiichi Sankyo and Genzyme filed suit for patent infringement against Impax in the US District Court for the District of Delaware. This action formally initiates the patent challenge process under the Hatch-Waxman Act. Based on the filing date of the ANDA, Impax believes that it is the first to file an ANDA with a paragraph IV certification and expects to be entitled to 180 days of market exclusivity.