Firdapse Approval Expanded to Children With Lambert-Eaton Myasthenic Syndrome

The approval was based on data from an expanded access program which evaluated the safety of amifampridine in 21 pediatric patients for at least 1 year.

The Food and Drug Administration (FDA) has expanded the approval of Firdapse® (amifampridine) to include patients 6 years of age and older with Lambert-Eaton myasthenic syndrome (LEMS). Previously, the treatment had been approved for adults with LEMS.

Firdapse is a broad spectrum potassium channel blocker. The approval was based on data from an expanded access program that evaluated the safety of Firdapse in 21 pediatric patients for at least 1 year. Findings demonstrated that while there was clinically significant weight loss reported in 2 pediatric patients at daily doses of 60mg and higher, adverse reactions in pediatric patients were similar to those seen in adult patients.

Use of Firdapse for this patient population was also supported by evidence from adequate and well-controlled studies of Firdapse in adults with LEMS, pharmacokinetic data in adult patients, and pharmacokinetic modeling and simulation to identify the dosing regimen in pediatric patients.

The most common adverse reactions with Firdapse include paresthesia, upper respiratory tract infection, abdominal pain, nausea, diarrhea, headache, elevated liver enzymes, back pain, hypertension, and muscle spasms.

“We are very pleased to have received FDA approval for the expanded pediatric indication for Firdapse. While the US LEMS pediatric population is an exceptionally small number of patients, this positive outcome helps ensure that all eligible LEMS patients have access to Firdapse for the treatment of this rare disease,” stated Patrick J. McEnany, Chairman and CEO of Catalyst. “This milestone represents our long-standing and unwavering commitment to the LEMS patient community, and we are pleased that this medicine is now available for this important patient population.”

Firdapse is available as 10mg functionally scored tablets in a 10-count blister pack, a carton containing 12 blister packs (120 tablets total), and 60- and 120-count bottles. For pediatric patients, the recommended dosing regimen is dependent on body weight. A suspension can be prepared with the tablets for patients who require dosage adjustment of less than 5mg increments, or who have difficulty swallowing or require a feeding tube.


  1. Catalyst Pharmaceuticals announces FDA approval of supplemental New Drug Application for Firdapse® expanding patient population to include pediatric patients. News release. Catalyst Pharmaceuticals. September 29, 2022. October 4, 2022.
  2. Firdapse. Package insert. Catalyst Pharmaceuticals; 2022. Accessed October 4, 2022.