amifampridine

Amifampridine (marketed as Firdapse by Catalyst Pharmaceuticals) is a small molecule, nonspecific voltage-gated potassium (K+) channel blocker indicated for the treatment of Lambert-Eaton Myasthenic Syndrome (LEMS) in adults and pediatric patients aged 6 years and older. By inhibiting potassium efflux in presynaptic nerve terminals, amifampridine prolongs the action potential duration and maintains depolarization, which keeps voltage-gated calcium channels open for an extended period. This increased calcium influx triggers the release of acetylcholine into the synaptic cleft, enhancing neuromuscular transmission and improving muscle function. Firdapse was the first FDA-approved treatment for LEMS, receiving approval for adults in 2018 and expanding to pediatric use in 2022.

Brand names

Firdapse

Other names

3,4-diaminopyridine phosphate3,4-DAP phosphateamifampridine phosphate