The Federal Circuit published a precedential decision on September 1, 2021 regarding the unenforceability of a pharmaceutical patent due to inequitable conduct.1 In Belcher Pharmaceuticals LLC v. Hospira, Inc., the Court (Judges Reyna, Taranto, and Stoll) affirmed the decision of the U.S. District Court for the District of Delaware (Judge Leonard P. Stark) that U.S. Patent No. 9,283,197 ("the '197 patent") was unenforceable due to inequitable conduct. Essentially the Belcher employee supervising patent prosecution failed to disclose prior art to the PTO that was directly relevant to certain claim limitations, while attempting to excuse that lapse based on his understanding of the claims. In particular, he believed that the prior art was irrelevant because that art required "overages" in the amount of active ingredient (i.e., an additional amount of an active ingredient or excipient compared to what is described in the product's label), but he was mistaken because the claims only required particular concentrations of active, rather than "overages."
Background
The '197 Patent
Belcher's '197 patent is directed to an injectable liquid formulation having a concentration of 1.0 – 1.06 mg/mL L-epinephrine, a pH between 2.8 and 3.3, and certain specified percentages of degradation products (D-epinephrine, formed by racemization) and adrenalone (formed by oxidation) over a shelf-life of at least 12-months.2
Claims 6 and 7 of the '197 patent, which were the only claims asserted against Hospira, are reproduced below:
6. An injectable liquid pharmaceutical formulation of L-epinephrine sterile solution; said liquid pharmaceutical formulation having a pH between 2.8 and 3.3; said injectable liquid pharmaceutical formulation compounded in an aqueous solution as 1.0 to 1.06 mg/mL L-epinephrine, and further including a tonicity agent; said liquid pharmaceutical formulation including no more than about 6% D-epinephrine and no more than about 0.5% adrenalone at release, and no more than about 12% D-epinephrine and no more than about 0.5% adrenalone over a shelf-life of at least 12 months.
7. The said injectable liquid pharmaceutical formulation of claim 6 further having a concentration of 1 mg per mL L-epinephrine.
Prosecution of the '197 Patent
During prosecution of the '197 patent, the examiner rejected the claims as obvious over Canadian Patent Application No. 2002643 A ("Helenek") in view of additional references.3 Helenek taught, amongst other things, a 1 mg/mL epinephrine injection at a pH between 2.2 to 5.0, and was made in an oxygen free environment to prevent oxidation of epinephrine.4 In response...
