Ranbaxy Laboratories Limited has submitted an Abbreviated New Drug Application (ANDA) for esomeprazole magnesium delayed-release capsules, 20mg and 40mg, containing Paragraph IV Certifications of invalidity and/or non-infringement with respect to certain AstraZeneca US patents listed in the Orange Book in reference to Nexium, the latter of which expires in 2018, according to the notice received by AstraZeneca from Ranbaxy Pharmaceuticals Inc.

AstraZeneca has 45 days within which to commence a patent infringement lawsuit against Ranbaxy that would automatically stay, or bar, the FDA from approving Ranbaxy's ANDA for 30 months or until an adverse court decision, whichever may occur earlier.

Ranbaxy has also certified with respect to certain other AstraZeneca US patents listed in the Orange Book in reference to Nexium that Ranbaxy will not launch its product prior to the expiry of those patents, the latter of which expires in October 2007, the notice says.

AstraZeneca is evaluating Ranbaxy's notice and continues to have full confidence in its intellectual property protecting Nexium, release from AstraZeneca said.