In re Metoprolol Succinate Patent Litigation
United States Court of Appeals for the Federal Circuit
494 F.3d 1011 (2007)
AstraZeneca and related entities (Astra) marketed extended-release metoprolol succinate as Toprol-XL. After a dispute over inventorship with Lejus Medical AB (Lejus), Astra and Lejus settled by dividing up patent claims to metoprolol succinate. Astra later obtained the '154 patent, whose only claim covered the compound metoprolol succinate itself, while Lejus separately held the '318 patent claiming an extended-release composition containing the compound. When Astra sued generic manufacturers for infringing the '154 patent, the defendants argued the '154 patent was invalid because it wasn't patentably distinct from the earlier '318 patent. The district court agreed and granted summary judgment against Astra, which appealed.
Whether a patent will be declared invalid for obvious-type double patenting if a later claim is not patentably distinct — that is, is obvious or anticipated — from an earlier claim.