Japan's Daiichi Sankyo has won a patent dispute in the USA against Mylan Laboratories, fending off a bid by the latter to launch a generic of its broad-spectrum antibiotic Levaquin (levofloxacin).

Daiichi Sankyo said the US Court of Appeals for the Federal Circuit backed a lower court ruling that a patent held by the Japanese firm as valid and would be infringed if Mylan went ahead with plans to launch its generic. The patent is not due to expire until December 20, 2010.

Johnson & Johnson has US rights to Levaquin and sells it there via its subsidiary Ortho McNeil Pharmaceutical. Both these companies were co-plaintiffs in the litigation.

Sales of the antibiotic are currently running at around $1 billion dollars a year, according to Daiichi Sankyo.