Prosecution Statements Rear Their Ugly Head

• Published date: 20 June 2023
• Subject Matter: Intellectual Property, Patent
• Law Firm: Finnegan, Henderson, Farabow, Garrett & Dunner, LLP
• Author: Ms Adriana Burgy and Stacy Lewis

Holding

In Azurity Pharms., Inc. v. Alkem Labs. Ltd., 2023 U.S. Dist. LEXIS 77839 (D. Del. May 4, 2023), the district court held that Azurity failed to show that Alkem's ANDA infringed the asserted claims.

Background

Plaintiff Azurity sued Alkem under the Hatch-Waxman Act for infringement of U.S. Patent No. 10,959,948 ("the '948 patent"). The '948 patent claims a composition and method of treatment for vancomycin oral liquid. Representative Claim 5 reads:

A non-sterile stable liquid formulation formulated for oral administration, consisting of:

(a) a buffering agent, wherein the buffering agent is selected from the group consisting of citric acid, sodium citrate, [and many other chemicals],

(b) water,

(c) a sweetener,

(d) a preservative, wherein the preservative is selected from the group consisting of sodium benzoate, parabens, benzoic acid, potassium sorbate, benzyl alcohol or salts thereof,

(e) vancomycin hydrochloride, and

(f)flavoring agent,

wherein the non-sterile stable liquid formulation is homogenous and stable for at least 1 week at ambient and refrigerated temperature and has a pH of 2.5-4.5.

Azurity alleged that the combination of two ingredients in Alkem's formulation, grape flavor and propylene glycol, met the "flavoring agent" limitation. That is, when grape flavor is mixed with propylene glycol in Alkem's ANDA product, the combination meets the "flavoring agent" limitation. Id at *36.

Azurity's expert testified that "the term 'flavoring agent' is used to mean 'a mixture of ingredients that imparts flavor to a formulation.'" Id. at *8. "Both parties' experts agreed that a single flavoring agent may contain multiple ingredients," including "non-flavorful" ingredients. Id.

Alkem argued that the presence of an unclaimed ingredient, propylene glycol, meant its formulation did not infringe. Id. at *4. Alkem's expert testified that "propylene glycol would generally not be considered for use as a flavor by itself because it has practically no taste." Id. at *9. Alkem's ANDA, however, "describes the whole of Grape Flavor 501417C, including its propylene glycol, as a 'flavoring agent.'" Id. at *13.

Alkem's ANDA also contains an additional 1 milligram per milliliter of propylene glycol described as a co-solvent. "[O]nce mixed, both propylene glycols interact equally with the grape-flavored chemicals in Grape Flavor 501417C." Id. at *14. The infringement dispute focuses on the "co-solvent" propylene glycol. Id. at *14.

Alkem also argued that Azurity...