In re Metoprolol Succinate Patent Litigation

Facts

Plaintiff's AstraZeneca AB, Aktiebolaget Hassle, and AstraZeneca L.P. (collectively "Astra") manufacture and market Toprol-XL, which is an extended release form of metoprolol succinate. In 1971, an Astra employee in Sweden synthesized metoprolol succinate. In 1982, another Astra employee in Sweden synthesized metoprolol succinate, possibly as directed by two other employees, Appelgren and Eskilsson. In 1983, Appelgren and Eskilsson left Astra and joined Lejus Medical AB. Lejus filed a Swedish patent application for an extended release form of metoprolol succinate and Appelgren and Eskilsson were listed as inventors. In 1985, Lejus filed for a U.S. patent, claiming priority from the Swedish patent. Astra commenced a transfer of ownership action that same year on the Swedish patent based on their employee being the inventor in 1971. Lejus and Astra settled the dispute of ownership with settlement agreement terms that assigned divided claims to Astra. Those claims included metoprolol succinate and pharmaceutical compounds with the active substance metoprolol succinate. Lejus kept the remaining claims of the '197 patent application. The Astra '897 Application was a continuation of the Lejus '197 Application and the continuation of the '897 Application resulted in the '154 Patent, which claimed only "Metoprolol succinate." Lejus received the '318 Patent at the same time, which included a claim in which metoprolol succinate was an active ingredient for an extended release compound. Astra filed multiple suits in various district courts claiming that several defendants were planning to manufacture and market generic versions of Toprol-XL which infringed Astra's patents. The defendants filed for summary judgment on the basis Astra's '154 Patent was invalid for double-patenting. Summary judgment was granted to defendants by the district court and the '154 Patent was found invalid for double-patenting over the Lejus '318 Patent.