AstraZeneca Pharmaceuticals LP has sued Osmotica Pharmaceutical Corp., marking the drug giant's latest effort to stop a rival from coming out with a generic version of schizophrenia treatment Seroquel XR®. Osmotica's version of the drug would infringe a patent held by AstraZeneca, according to a complaint filed Monday in the U.S. District Court for the Eastern District of North Carolina. Osmotica filed an abbreviated new drug application (ANDA) with the U.S. Food and Drug Administration seeking to market a generic version of Seroquel XR® before U.S. Patent Number 5,948,437 expires in 2017, the complaint alleges. The ‘437 patent covers the release of formulations of Seroquel XR's® active ingredient, known as quetiapine fumarate, and the processes for preparing and using those formulations. AstraZeneca is represented by Finnegan.