Objective
We evaluated the efficacy and safety of amifampridine phosphate (Firdapse®) for symptomatic treatment in Lambert‐Eaton myasthenic syndrome (LEMS).
Methods
Phase 3, randomized, double‐blind, study. Patients were treated initially with amifampridine phosphate for 7–91 days, followed by randomization to continue amifampridine phosphate for 14 days or placebo (7‐day taper, 7‐day placebo). The primary efficacy endpoints were changes from baseline at day 14 in Quantitative Myasthenia Gravis and Subject Global Impression scores.
Results
The coprimary efficacy end points and 1 of the secondary efficacy end points were met, showing a significant benefit of aminfampridine phosphate over placebo at Day 14. All 5 primary, secondary, and tertiary endpoints achieved statistical significance at Day 8. Amifampridine phosphate was well tolerated; the most common adverse events were oral and digital paresthesias, nausea, and headache.
Conclusions
This study provides Class I evidence of efficacy of amifampridine phosphate as a symptomatic treatment for LEMS. Muscle Nerve53: 717–725, 2016