The use of the word “about” in a patent claim as part of a numeric range might permit the patent holder to preclude competitor formulations falling outside the approximate range, as illustrated in a fairly recent decision Par Pharm., Inc. v. Hospira, Inc., 835 F. App'x 578 (Fed. Cir. 2020). Par sued Hospira for patent infringement after Hospira filed an ANDA seeking to market a generic version of Par’s Adrenalin® epinephrine injection. At issue was the scope of the patent claim listing the approximate amounts of tonicity, chelating, and pH lowering agents added to the epinephrine formulation for stability.
The Federal Circuit upheld a finding of literal infringement although the amount of the tonicity agent in Hospira’s formulation was outside the “about” range in Par’s patents. Par’s claim stated “about 6 to 8 mg/mL of a tonicity regulating agent,” while the ANDA identified 9 mg/mL of sodium chloride.
Hospira’s expert opined that “about” encompasses only “slight deviations” from a specific target concentration. However the Federal Circuit considered the purpose of the upper limit and its technologic context, which was to maintain a physiologically acceptable concentration in the human body (tonicity regulating agents ensure that fluid injected into the blood remains isotonic). Thus “about 8 mg/ml” encompasses 9 mg/ml, considering that isotonicity was the stated goal of Hospira’s inclusion of sodium chloride.
For the chelating agent, the court found Hospira’s own representations in its ANDA and related FDA disclosures determinative of the infringement analysis. “What a generic asks for and receives approval to market, if within the scope of a valid claim, is an infringement.” Id. at 585-86.[i] Hospira’s expert pointed out that the amount of the chelating agent in the generic’s test batches was below the “about 0.01 to 0.4 mg/mL” claimed in Par’s patents. The court did not find this controlling. Hospira represented to the FDA that the citric acid buffer has a chelating effect allowing it to complex with transition metals, and identified an upper limit of citric acid, which fell within the claim.
The Federal Circuit next examined whether the generic infringed “about 0.001 to 0.010 mL/mL of a pH lowering agent” claimed in Par’s patents. Hospira argued citric acid already included in the buffer system as a pH raising agent should not count toward the calculation of the pH lowering agent. The court found that Hospira waived this argument because the parties stipulated to claim construction that a pH-lowering component includes not only a pH lowering agent but also a pH raising agent. “Hospira agreed to claim constructions based directly on the specification passages.” Id. at 587. Thus Hospira's product would have a pH lowering agent in an amount within the claimed concentration range.
This decision underscores the importance of clearly establishing the purpose of numerical limitations, as well as preserving arguments for appeal.
[i] Quoting Sunovion Pharms., Inc. v. Teva Pharms. USA, Inc., 731 F.3d 1271, 1279 (Fed. Cir. 2013).
