Mexiletine

Pair of enantiomers

Mexiletine (INN) (sold under the brand names Mexitil and Namuscla) is a medication used to treat abnormal heart rhythms, chronic pain, and some causes of muscle stiffness. Common side effects include abdominal pain, chest discomfort, drowsiness, headache, and nausea. It works as a non selective voltage gated sodium channel blocker and belongs to the Class IB group of anti arrhythmic medications.

Mexiletine has several uses including the treatment of abnormal heart rhythms or arrhythmias, chronic pain, and myotonia. In general when treating arrhythmias, mexiletine is reserved for use in dangerous heart rhythm disturbances such as ventricular tachycardia. It is of particular use when treating arrhythmias caused by long QT syndrome. The LQT3 form of long QT syndrome is amenable to treatment with mexiletine as this form is caused by defective sodium channels that continue to release a sustained current rather than fully inactivating, however other forms of long QT syndrome can also be treated with this medication.

Common side effects of mexiletine include abdominal pain, chest discomfort, drowsiness, headache, nausea and skin reactions. Uncommon or rare side effects include seizures and liver dysfunction.]]

Mexiletine is available for human use in the US, and has been reintroduced in the UK as a licensed product, having previously only been available as a 'named patient' import. The drug is sold under the trade name Mexitil for use in arrhythmias and NaMuscla for use in myotonia.

Mexiletine is available to veterinarians in the US for the treatment of heart disease in dogs and cats. It is commonly used for the treatment of arrhythmogenic right ventricular cardiomyopathy (ARVC) in Boxer dogs in combination with sotalol.