On 1 March 2023, Catalyst Pharmaceuticals, Inc. and SERB SA (collectively the patent holders) filed suit against Lupin Limited, Lupin Pharmaceuticals, Inc., and Lupin, Inc. in the District of New Jersey, asserting infringement of six U.S. patents — US11268128B2, US11274332B2, US11274331B2, US10626088B2, US10793893B2, and US11060128B2 — all relating to Firdapse (amifampridine phosphate), a drug approved for the treatment of Lambert-Eaton myasthenic syndrome (LEMS). The trigger for the lawsuit was Lupin’s ANDA No. 217996, a generic drug application seeking FDA approval to market an amifampridine product in the United States.

After 911 days of litigation, the parties resolved the dispute through a consent judgment entered on 28 August 2025. The consent judgment prohibits Lupin and its affiliates, successors, and assigns from infringing the Licensed Firdapse Patents by making, using, selling, offering to sell, importing, or distributing the Lupin Product in the United States unless specifically authorised under the parties’ settlement agreement or the safe-harbour provision of 35 U.S.C. § 271(e)(1). All remaining claims, counterclaims, and affirmative defences were dismissed without prejudice and without costs. The court expressly retained jurisdiction to enforce the consent judgment and oversee performance under the settlement agreement.

A 911-day litigation timeline is broadly consistent with complex ANDA Paragraph IV patent disputes, though the consent judgment rather than a merits ruling suggests both parties identified commercial reasons to negotiate certainty. The settlement agreement itself — including any patent licensing terms, royalty obligations, or authorised entry date — is not part of the public record. The express preservation of FDA’s ability to grant final ANDA approval at any time suggests a conditional or date-triggered commercial licence may exist privately, though this cannot be confirmed from available filings.