ASTRAZENECA SUES RANBAXY OVER NEXIUM PATENT

AstraZeneca has filed a lawsuit in federal court accusing Indian generic firm Ranbaxy Laboratories of violating AstraZeneca's patent on blockbuster heartburn treatment Nexium.

Ranbaxy filed an abbreviated new drug application in October to market generic Nexium (esomeprazole magnesium) in 20- and 40-mg capsules. UK-based AstraZeneca responded last week by filing a patent infringement case against Ranbaxy in the U.S. District Court for the District of New Jersey. Nexium is one of AstraZeneca's most profitable drugs, generating $3.8 billion in sales in 2004.

The lawsuit accuses Ranbaxy of "willful infringement" of AstraZeneca's five substance patents covering Nexium, which is used to treat persistent heartburn caused by acid reflux disease. The patents expire between 2014 and 2019.