Pfizer defends Norvasc patent from Synthon

World drug giant Pfizer says that a federal court in the Middle District of North Carolina has upheld its US patent covering amlodipine besylate, the active ingredient in Norvasc, the world's most-prescribed branded medicine for hypertension. The patent had been challenged by the generic manufacturer, USA-based Synthon Pharmaceuticals.

Judge James Beaty ruled that the patent is valid and thereby infringed by the generic manufacturer's product. The decision, which is subject to appeal, prohibits Synthon from launching a generic version of the drug until September 2007.