UPDATE 1-Bayer appeals Yasmin patent ruling in U.S.

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FRANKFURT, March 31 (Reuters) - German drugmaker Bayer BAYG.DE has appealed against a ruling that some of its Yasmin oral contraceptive patents are invalid, the company said on Monday.

Bayer had sued generic manufacturer Barr Laboratories BRL.N for patent infringement in connection with Barr's application to the U.S. Food and Drug Administration for approval to market a generic version of Yasmin.

The drug generated sales of 321 million euros in the United States alone in 2007. Yasmin and its sister products Yaz and Yasminelle posted worldwide sales of 1.04 billion euros last year -- Bayer's largest product family by turnover.

Should Barr enter into the market with a cheaper copy, Bayer could face a dramatic decline in demand for Yasmin.

Bayer filed a Notice of Appeal in the U.S. District Court for the District of New Jersey, it said in a statement, after District Judge Peter G. Sheridan held early in March that certain Bayer patent claims were invalid because they would have been obvious to a person of ordinary skill in the art.

Barr had already conceded that its product infringed on Bayer's patent, but it argued in court for an invalidation that would allow it to market its generic copy.

The U.S. court ruling on March 3, capping years of legal wrangling, sent Bayer shares down over 4 percent and forced the company to slightly reduce its health-care profitability target for this year.

It now aims for its Bayer HealthCare unit to improve its core earnings (EBITDA) margin before special items "toward" 27 percent in 2008 from 25.6 percent in 2007. It previously targeting a 2008 health-care margin of about 27 percent.

Bayer said its appeal would be heard by the Federal Circuit, which is the federal court of appeals for patent cases. (Reporting by Frank Siebelt and Christiaan Hetzner, editing by Will Waterman and John Wallace)