US-based Pozen has received a preliminary injunction from a federal court ordering Par Pharmaceutical not to make and sell a generic version of its migraine drug Treximet.

Treximet (sumatriptan and naproxen sodium), sold by GlaxoSmithKline, was approved by the US Food and Drug Administration (FDA) in April 2008 for the acute treatment of migraine attacks, with or without aura, in adults.

Pozen has regulatory exclusivity of the drug, which expires on Friday 22 April.

The injunction will remain in effect until a final decision is issued in the pending patent litigation.

The company has also entered into a patent infringement lawsuit against Alphapharm, Teva Pharmaceuticals and Dr Reddy’s Laboratories.

Teva was dismissed without prejudice from the consolidated litigation in April 2010, but the case against the other three defendants was tried before Judge Leonard Davis in the Eastern District of Texas on 12-15 October 2010.

Pozen has three US patents on Treximet licensed to GlaxoSmithKline, two of which expire in August 2017 and one in October 2025.

The company continues to believe that its patents covering the drug are valid and enforceable.