Profile of aminopyridines for Lambert–Eaton myasthenic syndrome

Abstract

3,4-diaminopyridine (3,4-DAP) is an effective, symptomatic treatment for Lambert–Eaton myasthenic syndrome (LEMS). Several trials have studied the effects of 3,4-DAP in small numbers of LEMS patients. We systematically reviewed all randomized trials of 3,4-DAP in LEMS to determine the efficacy of this treatment using meta-analysis of clinical and electrophysiological end points. Data from four randomized, placebo-controlled trials revealed that muscle-strength scores increased significantly with 3,4-DAP. Limited meta-analysis performed on two trials using the quantitative myasthenia gravis score indicated that the clinical benefits seen were modest, with an improvement in quantitative myasthenia gravis score of 2.44 points (95% confidence interval: 1.2–3.6). Meta-analysis of the mean change in compound muscle action potential amplitude following 3,4-DAP treatment revealed a significant improvement compared to placebo (1.36 mV, 95% confidence interval: 0.99–1.72). 3,4-DAP is an effective, safe, first-line symptomatic treatment for LEMS, with significant clinical and electrophysiological benefits demonstrated by meta-analysis.