Par Pharmaceutical, Inc. v. Eagle Pharmaceuticals, Inc., No. 21-2342 (Fed. Cir. 2022)
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Since 2014 Par has manufactured and sold Vasostrict®, an FDA-approved vasopressin injection product used to treat patients with critically low blood pressure. The Orange Book identifies Par’s 785 and 209 patents as encompassing Vasostrict®. Both patents require the vasopressin composition to have a rounded pH between 3.7–3.9. In 2018, Eagle filed an abbreviated new drug application (ANDA) to manufacture and sell a generic version of Vasostrict® before those patents expired. Eagle represented in its release specification that the pH range would be between 3.4–3.6. Eagle’s ANDA also contained 35 U.S.C. 355(j)(2)(A)(vii)(IV) certification that Par’s patents are invalid or will not be infringed by Eagle’s proposed product.
Par sued for infringement under 35 U.S.C. 271(e)(2). Eagle stipulated that its proposed product would meet all asserted claim limitations except the claimed pH range. Par argued that “real-world” evidence shows the pH of Eagle’s product drifts up over time and that Eagle sought authority to release products into the marketplace with a pH of 3.64, just 0.01 beneath the infringing range. The Federal Circuit affirmed the rejection of those arguments. Minor fluctuations in pH value identified by Par did not reveal any discernible trend and the stability specification imposed an additional constraint that Eagle’s proposed product maintain a pH between 3.4–3.6 from the time of its distribution through its entire shelf life.
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