IP Law Daily, PATENT—D. Del.: Prior litigation over blood pressure drug patents did not preclude present suit, (Jan 11, 2023)

By Kevin M. Finson, J.D.

The scope of the earlier-asserted patent claims differed from the claims asserted in the present case.

A drug manufacturer seeking to manufacture a generic version of Azurity Pharmaceuticals’ Epaned® blood pressure medication was not entitled to judgment of on the pleadings on the ground of claim preclusion, the federal district court in Wilmington, Delaware, has held. Two prior cases asserting different patents against the defendant’s new drug application—resulting in judgment of noninfringement and stipulated dismissal—did not preclude the present case because the scope of the asserted patent claims in this case differed from the claims asserted in the prior cases (Azurity Pharmaceuticals, Inc. v. Bionpharma Inc., January 6, 2023, Goldberg, M.).

Azurity Pharmaceuticals, Inc. (Azurity) was the owner of U.S. Patents Nos. 1,040,023 (the ’023 patent) and 11,141,405 (the ’405 patent), which were asserted in what the parties referred to as the “third wave” of litigation against Bionpharma, Inc.’s Abbreviated New Drug Application (ANDA) for an oral liquid formulation of the blood pressure medicine enalapril maleate. Azurity sold the medication under the trade name Epaned®. Previous suits between the parties asserting other patents against the same ANDA—which were described as the “first wave” and “second wave”—had ended with a judgment of non-infringement following a bench trial and a stipulated dismissal, respectively. Bionpharma moved for judgment on the pleadings in the third wave suit, arguing that the resolution of the previous two suits had preclusive effect.

Claim preclusion. The major facts of the case were undisputed. The only dispute was on the appropriate test for determining if the present suit was based on the “same cause of action” as the prior suits for the purposes of claim preclusion. Azurity argued that the appropriate test was whether the scope of the asserted patent claims was essentially the same, while Bionpharma argued that the test should be whether the claims in the current suit would have been obvious to one skilled in the art who knew about the prior claims.

Reviewing Federal Circuit precedent, the court held that Bionpharma’s proposed claim preclusion test was derived from the area of obviousness-type double patenting, and was only mentioned as dicta in cases addressing claim preclusion. Azurity’s proposed test, on the other hand, arose from claim preclusion cases and was therefore applicable. The patents asserted in the third wave differed from those in the first two waves in that they did not contain a limitation addressing a pH buffer, so the parties agreed that if Azurity’s test was adopted the infringement claims in this case were not the same as those at issue in the first and second wave cases.

The court adopted Azurity’s proposed test and denied the motion for judgment on the pleadings.

The Case is No. 1:21-cv-01286-MSG.

Attorneys: Jack B. Blumenfeld (Morris, Nichols, Arsht & Tunnell LLP) for Azurity Pharmaceuticals, Inc. John C. Phillips, Jr. (Phillips, McLaughlin & Hall, P.A.) for Bionpharma Inc.

Companies: Azurity Pharmaceuticals, Inc.; Bionpharma Inc.

Cases: Patent DelawareNews