Pozen (Nasdaq: POZN) has prevailed in a patent fight over challenges to Treximet, a pain killer it developed along with GlaxoSmithKline (NYSE: GSK).

The Chapel Hill-based pharmaceutical firm has already sold future royalty rights and milestone payments that it would have received from GSK for $75 million.

On Monday, Pozen said a federal appeals court had upheld a verdict in Aug. 2011 in a case pitting Pozen against several generic drug firms who wanted to make and sell their own versions of Treximet.

“We are pleased that the Court of Appeals has upheld the Eastern District of Texas’ ruling in favor of POZEN, thus upholding the patents protecting Treximet,” said John Plachetka, Pozen’s chairman and chief executive officer.

Pozen sold the Treximet rights last November to an investment group.