Mexiletine is a class 1B antiarrhythmic agent used in the treatment of documented ventricular arrhythmias that warrant treatment. 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, like lidocaine, inhibits the inward sodium current required for the initiation and conduction of impulses, thus reducing the rate of rise of the action potential, Phase 0. It achieves this reduced sodium current by inhibiting sodium channels. Mexiletine decreases the effective refractory period (ERP) in Purkinje fibers in the heart. The decrease in ERP is of lesser magnitude than the decrease in action potential duration (APD), which results in an increase in the ERP/APD ratio.

Mexiletine Pathway (New) References