Background Mexiletine, a class 1b antiarrhythmic medication, appears to have some potential for treating muscle stiffness and other symptoms of myotonias. Purpose The aim of this study was to analyse the effect and safety of mexiletine on myotonia signs and symptoms in patients with myotonic disorders. Demographic (age and sex), diagnostic (type of myotonic disorder) and therapeutic (dosage, duration of treatment, previous treatment, adverse reactions) variables were gathered.
