Eisai v. Dr. Reddy's and Teva, Nos. 2007-1397, -1398 (Fed. Cir. 2008)
Patents on chemical compounds are holding up well to obviousness arguments in the Federal Circuit, even after KSR. In an opinion released today, the Federal Circuit affirmed the nonobviousness of rabeprazole, the active ingredient in Aciphex. This follows a decision last year affirming the nonobviousness of pioglitazone, the active ingredient in Actos.
Eisai's U.S. Patent No. 5,045,552 claims rabeprazole and its salts. Rabeprazole is in a class of drugs known as proton pump inhibitors, which suppress gastric acid production in the stomach. Aciphex (rabeprazole sodium) is indicated for the treatment of duodenal ulcers, heartburn, and associated disorders, and accounts for over $1 billion of Eisai's annual sales.
Dr. Reddy's stipulated to the validity of the '552 patent (relying on inequitable conduct arguments instead), but Teva challenged its validity, arguing that a combination of three prior art references rendered the claims of the '552 patent obvious: (1) European Patent No. 174,726, claiming lansoprazole; (2) U.S. Patent No. 4,255,431, claiming omeprazole; and (3) an article by Brandstrom et al., entitled "Structure Activity Relationships of Substituted Benzimidazoles".
