NEW YORK (AP) — Pfizer Inc. said Thursday a Canadian appeals court voided a patent protecting its blood pressure drug Norvasc, and said it plans to appeal the ruling. The New York drugmaker said the Canadian Federal Court declared the patent invalid. Pfizer said it is disappointed and will file an appeal to the Federal Court of Appeal of Canada. The challenge was brought by Ratiopharm, and covers the active ingredient in the drug, amlodipine besylate. The patent is scheduled to expire in 2010. If Pfizer is unable to get the ruling overturned on appeal, other companies will be able to start marketing less-expensive generic versions of the drug. Pfizer said legal challenges from generic drugmakers in Canada are still pending. Generic versions of Norvasc reached the U.S. market in March of 2007.
