Ranbaxy won US approval for a generic version of Valtrex at the beginning of this month, but GSK originally filed a lawsuit regarding Valtrex patents in 2003.
GSK has said that it will apply to the court for a preliminary injunction prohibiting the launch of this generic version of Valtrex.
According to GSK, the copycat Valtrex drug, infringes the basic “composition of matter” patent for Valtrex. The patent does not expire until June 2009. No trial date has yet been set for this litigation, GSK said.
Under the terms of an agreement between the companies, previously approved by the court, if GSK applies for such an injunction within 45 days, Ranbaxy will not launch its product until the court either rules on the preliminary injunction or decides the pending court case.
While several companies, including Ranbaxy Pharmaceuticals, have filed for US approval of generic Valtrex, Ranbaxy is the only generic manufacturer to have made a direct challenge to this basic patent.