A US federal appeals court has approved a request by Novartis and temporarily prohibited Teva Pharamceuticals from selling its generic version of the antiviral medicine Famvir, which has various US patents valid until 2015.

The order issued on September 7 by the US Court of Appeals for the Federal Circuit, which has nationwide jurisdiction in various subject areas that include patents, requires Teva to submit a response to the court by Tuesday, September 11.

The injunction remains in effect until a decision by this court. Teva launched its generic version "at risk" since patent litigation is still ongoing, and risks potentially significant damages if Novartis prevails. A trial date has not been set.