A New Jersey court in the US has ruled that Pfizer's patent over the acid reflux drug Protonix is valid and has been infringed by Teva Pharmaceutical Industries, which has been selling a generic version of the drug since 2007.
The US District Court for New Jersey rejected allegations by Teva and India's Sun Pharmaceuticals Industries that the patent covers an obvious variation of earlier patented compounds in the same family as Protonix.
Teva and Mumbai-based Sun have now been instructed to stop selling the generic until the patent expires in January.
A second trial will be held to determine what Pfizer should be paid for profit lost since Sun and Teva began distributing their version.
The original patent on Protonix is held by Swiss drugmaker Nycomed and was licensed to Wyeth, which is now owned by Pfizer.
Nycomed and Wyeth filed a patent infringement lawsuit against Teva and Sun in May 2004.