Catalyst Pharmaceuticals resolves final US patent litigation, securing FIRDAPSE market exclusivity through January 2035

A negotiated patent settlement on Firdapse (amifampridine) between Catalyst Pharmaceuticals and Hetero Labs Ltd. has closed the last open front in amifampridine patent litigation, establishing a defined generic entry date that extends branded protection by nearly a decade. Catalyst Pharmaceuticals (Nasdaq: CPRX), headquartered in Coral Gables, Florida, announced a settlement agreement with Hetero Labs Ltd., Hetero USA, Grace Consulting Services, Inc., and Annora Pharma Private Limited, resolving patent litigation initiated in response to Hetero’s Abbreviated New Drug Application seeking approval to market a generic version of amifampridine 10 mg tablets before the expiration of applicable patents. The settlement bars Hetero from launching a generic version of Firdapse in the US before a specified date in January 2035, subject to US FDA approval and certain customary carve-out provisions. Amifampridine is a voltage-gated potassium channel blocker approved for the treatment of Lambert-Eaton Myasthenic Syndrome, a rare autoimmune neuromuscular disorder.

Hetero’s ANDA filing triggered an automatic 30-month stay and subsequent litigation in the US District Court for the District of New Jersey. Trial had been scheduled to commence on May 18, 2026. Under the terms of the settlement, all ongoing patent litigation between Catalyst, its licensor SERB S.A., and the Hetero entities will be terminated prior to that date. The settlement confirms that Catalyst Pharmaceuticals’ Firdapse market exclusivity is effectively secured through January 2035 across all known ANDA challengers.

Prior settlements and the cleared litigation landscape

The Hetero agreement is the final resolution in a series of ANDA challenges to the Firdapse patent estate. Catalyst and SERB had previously settled comparable litigation with Lupin Pharmaceuticals, Teva Pharmaceuticals, and Inventia Healthcare Limited. With the Hetero Labs generic FIRDAPSE settlement now concluded, Catalyst has no remaining patent litigation pending with respect to Firdapse. The company stated explicitly that this settlement resolves all pending patent litigation relating to the product.

Firdapse acts by blocking voltage-gated potassium channels at the presynaptic neuromuscular junction. In Lambert-Eaton Myasthenic Syndrome, autoantibodies directed against P/Q-type voltage-gated calcium channels impair the release of acetylcholine from motor nerve terminals, producing proximal muscle weakness, autonomic dysfunction, and, in some patients, respiratory compromise. By prolonging nerve terminal depolarization through potassium channel blockade, amifampridine facilitates calcium influx and partially restores acetylcholine release, improving neuromuscular transmission.

LEMS is a rare condition, occurring most commonly as a paraneoplastic syndrome in association with small cell lung cancer, though a proportion of cases are autoimmune in origin without an identified underlying malignancy. The rarity of the condition and the mechanistic specificity of amifampridine’s action have historically supported a relatively narrow but defensible patent and regulatory exclusivity position.

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