Paediatric Medicines4 November 2026

Lupin wins approval for generic amifampridine, but patients may wait until 2035

The FDA has cleared a generic version of Firdapse, the Lambert-Eaton treatment labelled from age six. A patent settlement keeps it off the US market for more than eight years.

By NextGenHealth Editorial Team2 min read

People inside a well-stocked pharmacy with glass doors — Photo: Bernd Dittrich / Unsplash

In brief

FDA approval of Lupin's generic Firdapse changes little for now: a settlement bars its US launch before 25 February 2035, barring limited exceptions.

Lupin announced FDA approval of amifampridine 10 mg tablets, a generic of Firdapse, on 2 November 2026.
An August 2025 settlement bars a US launch before 25 February 2035 unless limited exceptions apply.
Firdapse's paediatric indication, from age six, rested on adult efficacy data, modelling and safety data.

Lupin announced on 2 November 2026 that the FDA had approved its abbreviated new drug application for amifampridine 10 mg tablets, a generic of Catalyst Pharmaceuticals' Firdapse. The medicine treats Lambert-Eaton myasthenic syndrome (LEMS), a rare neuromuscular disorder, in adults and in children aged six and over.

The approval will not bring a cheaper product to pharmacies any time soon. Under a settlement reached in August 2025, Lupin agreed not to market its generic in the US before 25 February 2035, unless certain limited exceptions apply, according to Contemporary Pediatrics. Lupin's own statement said nothing about launch timing or price.

A wall of settlements

Lupin says it is one of the first applicants and is eligible for 180 days of shared generic exclusivity. The value of that exclusivity now depends on a date more than eight years away.

Catalyst has settled with each challenger. Teva agreed in January 2025 not to launch before 25 February 2035. Hetero Labs agreed in May 2026 to a date in January 2035, and Catalyst said that deal resolved all pending patent litigation on the drug, after earlier settlements that also covered Inventia Healthcare. The terms of the Lupin deal are confidential, and Catalyst said in May that the Hetero agreement would go to the Federal Trade Commission and the Department of Justice for review.

Firdapse's orphan exclusivity expired on 26 November 2025. The remaining protection comes from patents listed as expiring between 2032 and 2037.

The approval settles a regulatory question. The commercial question was settled in private, more than a year earlier.

How the paediatric label was built

The FDA approved Firdapse in 2018 and extended it in September 2022 to patients aged six and over. There was no dedicated paediatric efficacy trial. Contemporary Pediatrics reports that the extension rested on adult efficacy studies, adult pharmacokinetics, pharmacokinetic modelling and safety data from patients aged six and over.

The label separates children by weight. Those weighing 45 kg or more follow the adult schedule, with a maximum single dose of 20 mg and 80 mg a day. Those under 45 kg start at 5 to 15 mg daily, with a maximum single dose of 10 mg and 40 mg a day. Safety and effectiveness below the age of six have not been established. In expanded access, 21 children received the drug for at least a year.

An unusual route to the youngest patients

Competition for this population has a history. The FDA approved Jacobus's Ruzurgi, the same active ingredient, in 2019 for patients aged six to 16. That approval was invalidated after a 2022 court ruling in Catalyst's favour, and Firdapse's label was widened that year.

LEMS is largely a disease of older adults. A 2025 Turkish nationwide analysis put prevalence at 1.11 per million, with a median age at diagnosis of 60. Children therefore make up a very small part of a very small market, which is one reason an extrapolated label was a practical route. For developers, the case shows how paediatric indications on rare disease products can be won without a dedicated trial, and how generic entry can still be set by private agreement long before regulators act.

Lambert-Eaton myasthenic syndrome
Amifampridine
Generics
Patent settlements
Lupin

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