Surprise Ruling: Court Invalidates Pfizer's Blood Pressure Drug Patent

The U.S. Court of Appeals for the Federal Circuit invalidated Pfizer's (PFE) patent on Norvasc today, clearing a major hurdle for Mylan (MYL) in its bid to launch a generic version of Norvasc. The FDA has already granted final approval to Mylan's ANDA for generic Norvasc and Mylan, as the first ANDA filer, holds the 180-day exclusivity rights. Norvasc (amlodipine besylate) is Pfizer's blockbuster treatment for high blood pressure, with annual U.S. sales of $2.5 billion.

Three different U.S. district courts had previously upheld the validity of Pfizer's Norvasc patent (U.S. Patent No. 4,879,303), making today's appeals court decision somewhat of a surprise. In January 2006, the Northern District of Illinois upheld the patent in Pfizer's case against Apotex; in August 2006, the Middle District of North Carolina upheld the patent in Pfizer's case against Synthon; and last month, the Western District of Pennsylvania upheld the patent in Pfizer's case against Mylan. All three district court decisions were appealed. Today's Federal Circuit decision came in the case against Apotex, though the invalidity ruling affects all three cases.

In the Federal Circuit opinion released today, a unanimous three-judge panel determined that claims 1-3 of the '353 patent, directed to amlodipine besylate and pharmaceutical and tablet formulations thereof, are invalid as obvious. More specifically, the court concluded that amlodipine besylate would have been obvious in light of Pfizer's own U.S. Patent No. 4,572,909, which discloses amlodipine and related compounds, together with various articles describing besylate salts of different compounds.

Generic Norvasc was not expected to hit the market until September, when Pfizer's pediatric exclusivity expires. Now, some analysts are predicting that Mylan will launch its generic Norvasc as early as next week. If that happens, Mylan should probably send a thank you gift to Apotex for achieving the invalidity decision in the Federal Circuit.

Before Mylan can launch its generic Norvasc, however, a court will need to lift the injunction that was entered when Pfizer defeated Mylan in the district court last month. Pfizer, for its part, announced in a press release today that it is considering all options, including filing a request with the Federal Circuit for reconsideration of today's decision.