A federal court in the Western District of Pennsylvania (Pittsburgh) has upheld Pfizer’s patent covering the active ingredient in its blockbuster hypertension drug Norvasc. The patent had been challenged by generic manufacturer Mylan. Judge Terrence McVerry ruled the patent covering Norvasc’s active ingredient, amlodipine besylate, is valid, enforceable and would be infringed by Mylan’s product. The decision, which is subject to appeal, prohibits Mylan from launching a generic version of Norvasc until Sept. 25, 2007. Mylan issued a statement saying that it disagrees with the court’s decision and would immediately appeal the ruling. Pfizer previously defeated challenges to the same patent brought by two other generic drug makers. In January 2006, a federal court in the Northern District of Illinois ruled against Canadian generic manufacturer Apotex. In August 2006, a federal court in the Middle District of North Carolina rejected a challenge by Dutch generic manufacturer Synthon. Both of those decisions have been appealed. Norvasc had annual US sales of $2.5 billion during 2006. Although the main patent on Norvasc will expire next month, the FDA has granted six months of pediatric exclusivity for Norvasc. When Mylan finally is able to launch its generic version of Norvasc, it will have 180 days of marketing exclusivity as the first abbreviated new drug application filer.