Global pharma firm AstraZeneca on Tuesday said it had filed a lawsuit in the United States District Court of New Jersey against India's biggest drug maker Ranbaxy Laboratories for "willful infringement" of its patent for acidity drug esomeprazole magnesium (marketed as Nexium).
The company in a statement on its website said the lawsuit was in response to an Abbreviated New Drug Application filed by Ranbaxy with the US Food and Drug
Administration regarding its intent to market a generic version of AstraZenecas Nexium in America prior to the expiration of six of its patents.
The expiration date for AstraZeneca's patents: 5,714,504; 5,877,192; 6,369,085; 6,428,810, 6,875,872 and 5,948,789 range from 2014 through 2019, the statement said.
AstraZeneca said it had "full confidence and will continue vigorously to defend and enforce its intellectual property rights protecting Nexium".
The drug is prescribed for gastro-esophageal reflux, also called heartburn or acid reflux.
Ranbaxy officials were not available for comment.
© 2026