PT  - JOURNAL ARTICLE
AU  - Mousele, Christina
AU  - Matthews, Emma
AU  - Pitceathly, Robert D.S.
AU  - Hanna, Michael G.
AU  - MacDonald, Susan
AU  - Savvatis, Konstantinos
AU  - Carr, Aisling
AU  - Turner, Christopher
TI  - Long-term Safety and Efficacy of Mexiletine in Myotonic Dystrophy Types 1 and 2
AID  - 10.1212/CPJ.0000000000001073
DP  - 2021 Oct 01
TA  - Neurology: Clinical Practice
PG  - e682--e685
VI  - 11
IP  - 5
4099  - http://cp.neurology.org/content/11/5/e682.short
4100  - http://cp.neurology.org/content/11/5/e682.full
AB  - Background and Objective Myotonic dystrophy types 1 and 2 are progressive multisystem genetic disorders whose core clinical feature is myotonia. Mexiletine, an antagonist of voltage-gated sodium channels, is a recommended antimyotonic agent in the nondystrophic myotonias, but its use in myotonic dystrophy is limited because of lack of data regarding its long-term efficacy and safety profile.Methods To address this issue, this study retrospectively evaluated patients with myotonic dystrophy receiving mexiletine over a mean time period of 32.9 months (range 0.1–216 months).Results This study demonstrated that 96% of patients reported some improvement in myotonia symptoms with mexiletine treatment. No clinically relevant cardiac adverse events were associated with the long-term use of mexiletine.Conclusions These findings support that mexiletine is both safe and effective when used long-term in myotonic dystrophy.Classification of Evidence This study provides Class IV evidence that mexiletine is a well-tolerated and effective treatment for myotonic dystrophy types 1 and 2.