IP Law Daily, PATENT—D. Del.: Antibiotic drug ANDA application did not infringe existing patent, (May 8, 2023)

By Kevin M. Finson, J.D.

The patentee had disclaimed during prosecution an ingredient added to the defendant’s accused product.

A generic drug manufacturer that had filed an Abbreviated New Drug Application did not infringe a competitor’s patent for liquids containing the antibiotic vancomycin, the federal district court in Wilmington, Delaware, has held. The defendant’s addition of propylene glycol in combination with grape flavor did not constitute a “flavoring agent” within the language of the patent claims because propylene glycol was clearly disclaimed during prosecution of the asserted patent (Azurity Pharmaceuticals, Inc. v. Alkem Laboratories, Ltd., May 4, 2023, Goldberg, M.).

Azurity Pharmaceuticals, Inc. (Azurity) was the owner of U.S. Patent No. 10,959,948 (the ’948 patent), which claimed a method for preparing and administering the antibiotic vancomycin in a liquid form mixed with water such that it would remain stable and uniform for at least one week. Alkem Laboratories, Ltd. (Alkem) filed an Abbreviated New Drug Application (ANDA), seeking FDA approval for its own mixture of vancomycin and water which was stable for at least one week. Azurity brought suit for infringement based on the ANDA. After a two-day bench trial, the court issued its findings.

Infringement. The parties agreed that Alkem’s application satisfied all of the claim limitations of the ’948 patent except for one: a limitation that the formula “consisted of” a certain list of ingredients, thereby excluding from patent coverage any formulation containing additional ingredients. Alkem argued that its formulation contained propylene glycol, an ingredient not present in the ’948 patent claims, and that the presence of this unclaimed ingredient defeated the infringement claims. Azurity argued that propylene glycol, in combination with grape flavor, constituted a “flavoring agent” which was within the patent claims.

Prosecution disclaimer. After a thorough review of four different formulations of claims which Azurity had presented to the USPTO in order to eventually obtain the ’948 patent, the court found that Azurity had clearly and unmistakably represented to the examiner that its product did not contain propylene glycol in its efforts to distinguish the prior art, which had used propylene glycol as a polar solvent.

Finding that Azurity had disclaimed any use of propylene glycol, the court held that Alkem’s ANDA containing propylene glycol did not infringe the ’948 patent.

The case is No. 1:20-cv-01094-MSG.

Attorneys: Neal C. Belgam, Eve H. Ormerod, and Daniel Taylor (Smith, Katzenstein, & Jenkins LLP) for Alkem Laboratories Ltd. Jack B. Blumenfeld and Eve H. Ormerod (Morris, Nichols, Arsht & Tunnell LLP) for Azurity Pharmaceuticals, Inc.

Companies: Alkem Laboratories Ltd.; Azurity Pharmaceuticals, Inc.

Cases: Patent DelawareNews