Suetterlin KJ, Bugiardini E, Kaski JP, et al. Long-term Safety and Efficacy of Mexiletine for Patients With Skeletal Muscle Channelopathies. JAMA Neurol. 2015 Dec 1;72(12):1531-3.
Submitted by Niranjan Singh, MD, News Science Editorial Board
Clinical and electrocardiogram data of 63 patients with non-dystrophic myotonias or hyperkalemic periodic paralysis due to CLCN1 or SCN4A mutations treated with mexiletine were analyzed retrospectively. Mexiletine doses ranged between 50 to 600 mg per day. Heart rate, PR interval, QRS duration, and corrected QT interval were calculated for each patient.
Patients with CLCN1 mutations tended to require higher doses of mexiletine as compared to those with SCN4A mutations. No serious adverse were identified with a mean follow up of 4.8 years per patient. Mexiletine did not change any of the cardiac parameters from their baseline measurements. Dyspepsia was the main side effect identified, occurring in 35% of patients.
Comment: Neuromuscular physicians often approach mexiletine initiation with trepidation, because the medication may lead to cardiac arrhythmias. No arrhythmias or alterations in EKG parameters were identified in this study, but it should be noted that it was small and retrospective, and vigilance concerning potential arrhythmia should not be relaxed.
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