Pfizer Inc said, that the Court of Appeals for the Federal Circuit has issued a decision reversing a lower court ruling upholding the company's US patent covering amlodipine besylate, the active ingredient in Norvasc.

Pfizer is reviewing the decision and is considering all its options, including seeking reconsideration.

Generic manufacturer Apotex filed the appeal after a lower court in the Northern District of Illinois had ruled that the Pfizer patent was valid and enforceable. The appellate panel ruled that the patent (US Patent No. 4,879,303) covering amlodipine besylate is invalid.

Pfizer disagrees with this decision. The company noted that two other trial courts had also found this patent to be valid and infringed.