<p>The patent had been challenged by the generic manufacturer Mylan. In 2002, Pfizer sued Mylan, claiming that it infringed the patent with its generic version of Norvasc, also known as amlodipine besylate. <br /><br />The court has now ruled that the patent covering 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 copycat until September 2007. <br /><br />This ruling is the latest in a series of favorable decisions for Pfizer and against generics manufacturers who have sought to invalidate Norvasc's US patent covering amlodipine besylate. <br /><br />In January 2006, a federal court in Illinois ruled against Canadian generic manufacturer Apotex; and in August 2006, a federal court in North Carolina rejected a challenge by Dutch generic manufacturer Synthon. Both of the decisions have been appealed.</p>