Canada appeals court backs Pfizer Lipitor patent

NEW YORK, March 20 (Reuters) - A Canadian appeals court has blocked the sale of a generic form of Pfizer Inc's (PFE.N: Quote, Profile, Research) top-selling cholesterol fighter, Lipitor, by India's Ranbaxy Laboratories Ltd (RANB.BO: Quote, Profile, Research), overturning a lower court ruling, Pfizer said on Thursday.

The Federal Court of Appeal of Canada issued an order prohibiting approval of Ranbaxy's product in Canada until a Pfizer patent expires in July 2010, the company said.

The lower court had ruled that the enantiomer, or calcium salt, patent could not block Ranbaxy from seeking approval for a cheaper generic form of the world's biggest prescription medicine. Lipitor, known generically as atorvastatin calcium, has annual sales of about $12 billion.

Ranbaxy may seek a review of the decision by the Supreme Court of Canada, Pfizer said. (Reporting by Bill Berkrot)