The drugmaker is seeking an injunction barring the FDA from granting final marketing approval of generic forms of the drug, whose chemical name is quetiapine, until December 2, 2012, or at least until a federal court has a chance to review the agency's action.
Last week, the FDA denied AstraZeneca's Citizen Petitions requesting the agency withhold approving any generic with labelling that did not have certain warning language required for its branded version.
Generic copies of the original instant-release form of Seroquel are due to hit the U.S. market on March 26 when AstraZeneca's patent expires - an event that will have a significant impact on both sales and profits.
AstraZeneca is currently budgeting for a 2012 revenue fall at the group level of more than 10 percent, in large part as a result of loss of exclusivity on Seroquel in the both United States and Europe.
Seroquel is a particularly profitable medicine for the Anglo-Swedish drugmaker and analysts at Berenberg estimate its loss could knock 330 basis points off the group's pre-R&D margin.
With acid reflux treatment Nexium also facing U.S. generics in 2014 and top-selling cholesterol fighter Crestor losing patent protection in 2016, AstraZeneca is stepping up the drive to buy in replacement products through a series of acquisitions.
(Reporting by Ben Hirschler; Editing by Hans-Juergen Peters)