(New throughout, adds comment from Jazz)
By Jan Wolfe
July 13 (Reuters) - A U.S. appeals court on Friday ruled invalid patents owned by Jazz Pharmaceuticals PLC covering its narcolepsy drug Xyrem, giving Amneal Pharmaceuticals Inc a boost in its effort to launch a generic version of the medicine.
The U.S. Court of Appeals for the Federal Circuit affirmed a series of rulings in favor of Amneal that the Jazz patents described obvious ideas. Shares of Jazz fell 2.5 percent to $175 in morning trading, while Amneal was up 1 percent to $18.50.
Jazz said in a statement it was disappointed in the ruling but that it only involves a "subset" of its patents covering Xyrem.
"We remain confident in the strength of our remaining patent estate for Xyrem," Jazz said.
Amneal did not immediately respond to requests for comment.
Amneal had asked an administrative court run by the U.S. Patent and Trademark Office to cancel the patents in hopes of bringing a generic version of Xyrem to market.
The patent tribunal sided with Amneal in 2016, prompting an appeal by Jazz.
Xyrem generated more than $1.1 billion in sales in 2017, accounting for about 70 percent of Jazz's revenue.
Xyrem is an approved treatment for both excessive daytime sleepiness and cataplexy in patients with narcolepsy, a chronic neurological disorder.
Amneal has sought to invalidate other Jazz patents covering Xyrem through litigation in federal court in New Jersey. That case remains pending. (Reporting by Jan Wolfe Editing by Chizu Nomiyama, Dan Grebler and David Gregorio)