INOMax® (nitric oxide)
Case Name: Mallinckrodt Pharms. Ireland Ltd. v. Airgas Therapeutics LLC, Civ. No. 22-1648-RGA, 2025 WL 472557 (D. Del. Feb. 12, 2025) (Andrews, J.)
Drug Product and Patent(s)-in-Suit: INOMax® (nitric oxide); U.S. Patents No. 8,795,741 (“the ’741 patent”) and 8,776,794 (“the ’794 patent”)
Nature of the Case and Issue(s) Presented: Mallinckrodt sued Airgas for patent infringement. Airgas submitted an ANDA seeking approval for its generic product called Ulspira. The patents-in-suit claim method of treating patients with inhaled nitric oxide (iNO) while reducing the risk of adverse effects. They cover Mallinckrodt’s INOMax product, an iNO gas product administered bedside in a hospital to neonates and children suffering from hypoxic respiratory failure. One claimed treatment is for neonates who suffer from left ventricular dysfunction (LVD). If these patients take iNO, they have a high risk of experiencing serious adverse effects, like pulmonary edema.
Mallinckrodt filed its lawsuit on Dec. 30, 2022. Airgas received approval for its ANDA on July 27, 2023. Mallinckrodt moved for a preliminary injunction preventing Airgas from marketing its product. Airgas launched Ulspira while the motion was pending, and the court denied Mallinckrodt’s motion.
Why Airgas Prevailed: The court first addressed Mallinckrodt’s likelihood of success on the merits. The ’741 patent. Mallinckrodt argued that it was likely to succeed on its allegation that Airgas induced infringement of claims 24 and 26 of the ’741 patent because the label on Airgas’ Ulspira product encouraged medical professionals to infringe the claims by instructing them on how to perform the claimed method. The court disagreed. Claim 24 requires a doctor to identify a patient with LVD and treat that patient without “either (i) administration of inhaled nitric oxide for fourteen days or (ii) administration of inhaled nitric oxide until the ... patient’s hypoxia has resolved.” The court found that one plausible interpretation of Airgas’s label was to instruct discontinuing Ulspira once the doctor learned the patient had LVD only after starting the treatment, and that that interpretation would not fall within the asserted claim. The court also found that Airgas raised a substantial question of invalidity of the asserted claims; specifically, that the claims at issue here were very similar to claims previously invalidated as being directed to a natural phenomenon that adds no inventive concept.
The ’794 patent. Mallinckrodt argues it is likely to succeed on its allegation of induced infringement of claim 1 of the ’794 patent because Ulspira’s operating system connects to Airgas’ iNO gas cylinder by a valve and contains circuitry to store and to communicate data. Based on a prior litigation and the patent’s specification, the claimed “gas data” relates to “the actual gas inside the cylinder.” Airgas therefore argued that it could not infringe because none of the “gas data” measured by Airgas’ product as alleged by Mallinckrodt is “the actual gas inside the cylinder.” The court credited Airgas’s argument that its products do not verify data of “the actual gas data inside the cylinder.” But given that the ’794 patent withstood an IPR challenge, the court did not find that Airgas raised a substantial question of validity.
The court next addressed irreparable harm. Mallinckrodt argued that it would be harmed because Airgas could bid on its expiring contracts, but Mallinckrodt renewed about 90% of its contracts. As of Oct. 1, 2024, Airgas had sold zero units of, and obtained zero revenue from, Ulspira, and only procured one service contract, evidencing taking a customer away from Mallinckrodt, as of December 2024. Other non-renewals of Mallinckrodt contracts were likely because of a third competitor—Praxair—not Airgas. The fact that Mallinckrodt renewed 90% of its contracts also renders devalues its lost market share and price lowering arguments. The court further found that Mallinckrodt’s price erosion and harm to its overall business arguments were highly speculative.
