Azurity Pharmaceuticals, Inc. v. Alkem Laboratories Ltd., Appeal No. 2023-1977 (Fed. Cir. Apr. 8, 2025)

In our Case of the Week, the Federal Circuit affirmed that defendant Alkem’s proposed generic antibiotic did not infringe claims of a patent that covers appellant Azurity’s Firvanq® medication. The Court found that during prosecution of a related patent, Azurity had made “sweeping” disclaimers of any formulation that contains propylene glycol, an ingredient used as a solvent and in certain flavoring agents. Because Alkem’s Abbreviated New Drug Application (ANDA) made clear that its generic formulation includes propylene glycol, the Federal Circuit affirmed the district court’s judgment of non-infringement.

At issue was Azurity’s U.S. Patent No. 10,959,948, which claims drinkable formulations of vancomycin hydrochloride, an antibiotic used to treat Clostridium difficile infections. The asserted claims recited formulations “consisting of” a buffering agent, water, a sweetener, a preservative, vancomycin hydrochloride, and a flavoring agent. In contrast to the open-ended phrase “comprised of,” it is understood as a convention of patent law that “consisting of” means a claimed combination contains only the elements expressly recited in the claim. Having reviewed the relevant prosecution history, the Court explained this language had been adopted during prosecution of the ’948 patent’s parent application to distinguish a prior art reference referred to as Palepu. Palepu teaches vancomycin hydrochloride formulations, including propylene glycol, as a solvent; and the applicant had repeatedly distinguished Palepu on grounds that Azurity’s claimed formulations did not include propylene glycol. The examiner rejected the applicant’s proposed negative limitations to that effect for lack of written description, however, and ultimately recommended adoption of a “consisting of” preamble to overcome Palepu. After the parent claims were allowed on that basis, the application that would become the ’948 patent was filed as a continuation and allowed without rejection. The Federal Circuit confirmed the clear disclaimer in the parent application’s prosecution history applied to the “consisting of” claims in the ’948 patent.

The Court also rejected Azurity’s argument that it had only distinguished propylene glycol as a solvent (the way it was used in Palepu), and that its claims could still cover formulations that use propylene glycol as a flavoring agent. The Federal Circuit pointed out that Azurity’s proposed negative limitations and other prosecution statements had been broadly directed to the absence of propylene glycol in general, and that the public notice function of such statements required Azurity to be held to them, even if they were broader than necessary to distinguish Palepu. Azurity also argued the parties had stipulated before trial that “[s]uitable flavoring agents … include flavoring agents with or without propylene glycol,” but the Court found the stipulation had been properly interpreted as establishing a fact about the field of art, not claim scope. After it learned of Alkem’s ANDA, Azurity had also made a submission in another, related, pending patent application which stated: “For the record, Applicant did not disclaim propylene glycol when submitting the arguments in [the ’948 patent’s application]… .” The Federal Circuit observed that such a statement might have affected the construction of a later-issued patent, but with regard to the then-allowed claims of the ’948 patent, “Azurity’s unilateral and belated statement carries no weight.”

The panel concluded that, at bottom, “[t]he infringement inquiry here is very simple: propylene glycol was disclaimed; the ANDA contains propylene glycol; therefore there is no infringement.” Accordingly, the Federal Circuit affirmed the district court’s judgment of non-infringement.

The opinion can be found here.

By Jason A. Wrubleski

ALSO THIS WEEK

In re SAP America, Inc., Appeal No. 25-118 (Fed. Cir. Apr. 10, 2025)

In response to a petition for a writ of mandamus that sought transfer to a different division of the Eastern District of Texas, the Federal Circuit denied it. SAP sought transfer of the case from the Marshall Division to the Sherman Division, in part because it had offices in Sherman and two potentially relevant witnesses were there. After a nine-month delay, Judge Gilstrap denied the request, and noted the case was proceeding to trial. The judge further noted a relationship to a co-pending case against AT&T based on one of the same patents. The Federal Circuit found that Judge Gilstrap had erred in considering the AT&T litigation, given that it had been completely resolved by the date the district court had entered its order; and that the court had further erred in considering the pace to trial as of the time the motion was decided, because the correct time for the analysis is the time when the motion to transfer is filed. The district court had also set an overly demanding standard for considering the “willing-witness” factor. But the Federal Circuit nonetheless agreed that SAP had failed to meet the standard for transfer on balance of all the factors.

The opinion can be found here.

By Nika Aldrich

This article summarizes aspects of the law and does not constitute legal advice. For legal advice with regard to your situation, you should contact an attorney.