Efficacy of 3,4-Diaminopyridine and Pyridostigmine in the Treatment of Lambert–Eaton Myasthenic Syndrome: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study

3,4-Diaminopyridine and pyridostigmine are widely used to treat Lambert-Eaton myasthenic syndrome (LEMS), either alone or in combination. 3,4-Diaminopyridine enhances the release of acetylcholine at the neuromuscular synapse, and pyridostigmine inhibits the degradation of this neurotransmitter. Although this could lead to a synergistic effect on neuromuscular transmission, no studies have compared the effects of these drugs in patients with LEMS. Therefore, we performed a placebo-controlled, double-dummy, double-blind, randomized, crossover study in nine patients with LEMS.