The Northern District of Illinois (Chicago) has upheld the company's US patent covering amlodipine besylate, the active ingredient in Norvasc, the world's most-prescribed branded medicine for treating hypertension. The patent had been challenged by the generic manufacturer Apotex.

Judge James M. Rosenbaum ruled that the patent (US Patent No. 4,879,303) covering amlodipine besylate is valid, enforceable and infringed by the generic manufacturer's product. The decision, which is subject to appeal, prohibits Apotex from launching a generic version of amlodipine until September 2007, claims a Pfizer release.

"The court decision is another important victory for medical innovators who invest in high-risk research to develop life saving medicines, as well as for the patients who benefit from those medicines. We are gratified that the court has affirmed the validity of our Norvasc patent, and we will continue to defend against any and all patent challenges that seek to undermine our mission of finding new therapeutic options for the patients we serve," said Jeffrey Kindler, vice chairman and general counsel of Pfizer.

Pfizer continues to face challenges from other generic manufacturers who are seeking to invalidate Norvasc's US amlodipine besylate patent as well as a second basic compound patent covering amlodipine. Those challenges are expected to be heard later this year.