Case Name: Azurity Pharms., Inc. v. Alkem Labs. Ltd., No. 20-cv-1094, 2023 WL 3254117 (D. Del. May 4, 2023) (Goldberg, J.)

Drug Product and Patent(s)-in-Suit: Firvanq® (vancomycin); U.S. Patent No. 10,959,948 (“the ’948 patent”)

Nature of the Case and Issue(s) Presented: Vancomycin is an antibiotic used to treat clostridium difficile bacterial infections. The ’948 patent claims a non-sterile stable liquid formulation consisting of a buffering agent, water, sweetener, a preservative, a flavoring agent, and vancomycin hydrochloride. Alkem argued that its ANDA product did not infringe the ’948 patent. The court agreed.

Why Alkem Prevailed: To prove infringement Azurity had to “fit each ANDA ingredient within the asserted claims.” In other words, no ANDA ingredient could be left over because any remaining ingredient would violate the “consisting of” preamble limitation. Azurity disagreed and argued that it had proven that mixing and matching certain ANDA ingredients turned them into the claimed ingredients. More particularly, Azurity argued that when grape flavor is mixed with propylene glycol, the combination is a “flavoring agent.” Because flavoring agent is a claimed ingredient, Alkem’s propylene glycol, which otherwise did not have a claimed function, would not violate the “consisting of” language.

As a threshold matter, Alkem argued that it could not infringe because its ANDA described the propylene glycol as a co-solvent. But the court explained that the ANDA was not determinative and that it did not preclude Azurity from offering evidence that propylene glycol also functioned as a flavoring agent.

Alkem argued that Azurity disclaimed propylene glycol during prosecution. In response, Azurity explained that this was a claim construction issue and that Alkem waived this argument by agreeing that no claim terms require construction. The court disagreed, finding that Alkem’s disclaimer argument was not a surprise given it was raised in its Answer to the Complaint. Additionally, the court explained that refusing to consider evidence on the meaning of “flavoring agent” would make the infringement inquiry more difficult. Specifically, without claim construction, the court could not decide whether grape flavor and propylene glycol combine to make a “flavoring agent.”

On the merits, the court found that disclaimer applied to Azurity’s claims. Specifically, the court found that during prosecution, Azurity argued that the absence of propylene glycol and polyethylene glycol in the claimed invention, distinguished it from the Examiner’s cited art. The court explained that because Azurity used the words “absence” and “does not include,” it could not now reverse course and say its invention includes propylene glycol.