Mexiletine versus lamotrigine in non-dystrophic myotonias: a randomised, double-blind, head-to-head, crossover, non-inferiority, phase 3 trial

Non-dystrophic myotonias are skeletal muscle channelopathies caused by ion channel dysfunction. Symptom onset is frequently in the first decade of life, causing disability in a young cohort. Although there is no cure, symptomatic treatments exist. Previous trials provide evidence of the efficacy of mexiletine. More recently, lamotrigine has been shown to be effective. Both treatments have different profiles, including pharmacokinetics and adverse events. This trial aimed to investigate whether lamotrigine is non-inferior to mexiletine to directly inform clinical practice.