In re Metoprolol Succinate Patent Litigation

Brief Fact Summary. Two pharmaceutical manufacturers patented extended release compounds with the active ingredient metoprolol succinate.  One of the manufacturers sued several generic manufacturers for infringing on their patent and the court held the manufacturer’s patent invalid due to double-patenting. 

Synopsis of Rule of Law. To earn patent protection, patent claims may be similar but must be non-obvious and “patentably distinct.”

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.

Issue. To earn patent protection, must patent claims although similar be non-obvious and “patentably distinct?”

Held. (Gajarsa, J.)  Yes.  To earn patent protection, patent claims may be similar but must be non-obvious and “patentably distinct.”  The judicially created doctrine of obviousness-type double patenting avoids extending patent protection to two inventions that may not be the “same” invention but are so similar as to be patentably indistinct.  The ‘318 Patent claims a compound that releases metoprolol succinate.  The ‘154 Patent claims the composition of metoprolol succinate itself.  The ‘318 Patent was found by the district court to be the genus of the species claimed by the ‘154 Patent.  The species claim came first, so the district court invalidated the ‘154 Patent claim for double-patenting since it was not patentably distinct.  The issue becomes whether the claims were patentably distinct because the claim comparison is correct.  Astra argues the genus/species relationship is inaccurate because the appropriate relationship is element/combination.  Previously this court held that such semantics are irrelevant and therefore the argument fails.  Astra then relies on three prior cases, but those cases are distinguishable or overcome by later case law.  In re Emert, 124 F.3d 1458 (Fed. Cir. 1997), requires this court to affirm the ‘154 Patent as invalid.  Emert invalidated a patent for double-patenting on the basis that patenting the element is obvious after reviewing a patent of a compound containing the element.  Similarly in this case, the patent claim for metoprolol succinate is obvious from the patent on the delivery of metoprolol succinate and therefore a double-patent issued in error.  Affirmed in part.

Dissent. (Schall, J.)  The ‘154 Patent claim is patentably distinct from the ‘318 Patent claim.  The compound metoprolol succinate has not been claimed twice.  The ‘318 Patent claims a compound which may include the element, but what is claimed is the compound as a whole.  The ‘154 Patent does not claim any type of compound at all.  Emert does not control in this case because that case involved two claims to an oil-soluble dispersant.  The decision by the district court should be reversed.

Discussion. By filing a “terminal disclaimer,” the issue of double-patenting can be avoided.  The terminal disclaimer is appropriate when one inventor holds more than one patent on the same invention.  The disclaimer is enforceable only if all patents are commonly owned and states the later patent will expire at the same time as the first.  However, in this case, the ownership dispute prevented a terminal disclaimer filing and resulted in the patent’s invalidity.