Federal Circuit Affirms Noninfringement Ruling in Hatch-Waxman Litigation Based on Claim Construction, Prosecution History Estoppel, and the Disclosure-Dedication Rule

In Actelion Pharms. Ltd v. Mylan Pharms. Inc., No. 2024-1641 (Fed. Cir. May 13, 2026), the Federal Circuit affirmed the district court’s findings of noninfringement, both literally and under the doctrine of equivalents.

Following Mylan’s ANDA filing, Actelion sued Mylan for infringement of two patents directed to pharmaceutical compositions of epoprostenol, the active ingredient in Actelion’s hypertension drug Veletri®. In a bench trial, the district court found that Mylan did not literally infringe, that Actelion was barred from asserting infringement under the doctrine of equivalents due to prosecution history estoppel, and that, regardless, Actelion had not proven infringement by an equivalent. Actelion appealed.

On appeal, the Federal Circuit affirmed the district court’s finding of no literal infringement, finding no error in the district court’s claim construction. The Federal Circuit found that both intrinsic and extrinsic evidence supported the district court’s construction of the term “pH of 13 or higher” to refer to a pH measured at standard temperature. The Federal Circuit also upheld the district court’s application of prosecution history estoppel to bar Actelion from asserting infringement under the doctrine of equivalents because the amendment adding the pH limitation was not only tangential to the differences between the alleged equivalent and the literal claim scope. The Federal Circuit also found the disclosure-dedication rule barred the assertion of infringement under the doctrine of equivalents because the asserted patents disclosed unclaimed alternatives to the limitation in question, which Actelion could not recapture as an equivalent.