AstraZeneca has filed a lawsuit in the US District Court for the District of New Jersey against Ranbaxy Laboratories for wilful infringement of AstraZeneca’s patents protecting Nexium (esomeprazole magnesium).

The lawsuit is in response to an Abbreviated New Drug Application filed by Ranbaxy with the US Food and Drug Administration regarding Ranbaxy’s intent to market a generic version of AstraZeneca’s Nexium in the US prior to the expiration of six AstraZeneca Patents: 5,714,504; 5,877,192; 6,369,085; 6,428,810, 6,875,872 and 5, 948,789. The expiration dates for these patents range from 2014 through 2019, stated an AstraZeneca release.