UPDATE 1-US appeal court: Purdue claims for tramadol invalid

Thu Jun 3, 2010 12:19pm EDT

* Patent claims were for controlled-release tramadol

* Court rejects claims of misconduct by Purdue

* Par Pharmaceutical shares up nearly 3 percent

WASHINGTON, June 3 (Reuters) - Purdue Pharma Products' patent claims for controlled-release tramadol, a pain medication, are invalid, the U.S. Court of Appeals for the Federal Circuit affirmed in a ruling issued on Thursday.

Generic drugmaker Par Pharmaceutical Inc PRX.N had argued that the patent claims should be deemed invalid because they were an obvious, or easy to devise, improvement of existing knowledge.

Par's stock was up 2.9 percent to $28.49 in noon trading on the New York Stock Exchange.

Purdue, Napp and Ortho-McNeil filed suit against Par Pharmaceuticals in 2007 after Par said it planned to bring out a generic version of 100- and 200-mg tramadol. Par said in November that it received U.S. regulatory approval to market the copycat version.

Although Purdue owned the patent, tramadol, sold as Ultram, is made by Johnson & Johnson's (JNJ.N) Ortho-McNeil.

The appeals court also affirmed the Delaware District Court ruling that Purdue had not engaged in inequitable conduct, essentially an attempt to mislead the patent office.

The case was appealed from the U.S. District Court for the District of Delaware.

The case is Purdue Pharma Products LP and Napp Pharmaceutical Group Ltd, and Ortho-McNeil Inc v. Par Pharmaceutical Inc, 09-1553 and 09-1592. (Reporting by Diane Bartz; Editing by Tim Dobbyn)