Another reminder that it is generally not good practice to characterize “the invention” as relating to any particular embodiments. By “conspicuously choosing only certain members of [a] class,” and referring to them as “the invention,” the patentee will be considered to have “conveyed a clear and definitive meaning that it was disclaiming other members of the class.”
Background / Facts: The patent at issue here relates to the drug omeprazole (and its preferred enantiomer esomeprazole), which is an “effective gastric acid secretion inhibitor[], and [is] useful as [an] antiulcer agent[].” In this regard, the claims recite pharmaceutical compounds that contain certain esomeprazole salts as an active ingredient, in particular those containing an “alkaline salt” or “pharmaceutically acceptable salt.” The specification, however, refers only to six specific cations for such salts, including Na+, Mg2+, Li+, K+, Ca2+ and functional group N+(R)4 salts. The patentee, AstraZeneca, sells Nexium, a product whose active ingredient is the Mg2+ salt of esomeprazole. The accused infringer, a generic drug maker, is seeking approval to sell a product that contains a Sr2+ salt of esomeprazole, strontium not being one of AstraZeneca’s listed six cations.
Issue(s): Whether the written description limits “alkaline salt” in the patent to certain specifically named salts.
Holding(s): Yes. “It is undisputed that the term ‘alkaline salt,’ on its face and outside the context of the … patent, would not be limited to the six cations named in the district court’s claim construction. But we agree with the district court that this is a patent in which the written description, by clear disclaimer, limits the claim scope to those cations. The first sentence of the Detailed Description declares: The present invention refers to the new Na+, Mg2+, Li+, K+, Ca2+ or N+(R)4 salts of the single enantiomers of omeprazole, where R is an alkyl with 1-4 carbon atoms, i.e. Na+, Mg2+, Li+, K+, Ca2+ or N+(R)4 salts of (+)-[omeprazole] and (-)-[omeprazole], where R is an alkyl with 1-4 carbon atoms. … That language clearly defines ‘the present invention’ not as salts of omeprazole, or salts of single enantiomers of omeprazole, but as a particular set of ‘new’ salts of enantiomers of omeprazole, limited to the six named cations. … Those statements clearly confine the invention to the six identified cations, disclaiming anything else.”