Mexiletine hydrochloride is used for the treatment of documented ventricular arrhythmias (e.g., sustained ventricular tachycardia) that in the judgment of the clinician are life-threatening. Because of the drug's arrhythmogenic potential and the lack of evidence for improved survival, use of mexiletine for less severe arrhythmias is notrecommended.
Mexiletine hydrochloride can reduce VPCs, paired VPCs, and nonsustained ventricular tachycardia and can suppress the recurrence of ventricular tachycardia and/or fibrillation in patients with ventricular tachycardia and/or fibrillation. However, treatment of asymptomatic ventricular premature contractions (VPCs) should be avoided. (
See Increased Mortality Associated with Antiarrhythmic Drugs under Warnings/Precautions: Warnings, in Cautions.) Mexiletine also has suppressed Holter monitor evidence of sustained ventricular tachycardia and ventricular tachycardia induced by programmed electrical stimulation (PES). In addition, mexiletine has been effective in some patients for the treatment of ventricular arrhythmias unresponsive to other antiarrhythmic agents.
Results of placebo- or comparative drug-controlled studies indicate that efficacy of mexiletine in reducing the frequency of VPCs, paired VPCs, and episodes of nonsustained ventricular tachycardia has been greater than that of placebo and similar to that of other class I antiarrhythmic agents (e.g., disopyramide, procainamide, quinidine).
Mexiletine hydrochloride has been used with equivocal results for the management of diabetic neuropathy. Efficacy has been evaluated in several randomized, placebo-controlled trials in a limited number of patients 45 years of age and older with prolonged painful diabetic neuropathy (for several months or years), who had long-standing (10 years or more) type 1 or 2 diabetes mellitus. Pain relief frequently was measured by a decrease in a visual analog pain score (VAS) using a 100-mm line as a pain scale. In a crossover study, about 67% (10 of 15) patients receiving mexiletine hydrochloride (10 mg/kg daily) experienced at least a 15-mm reduction in VAS score, while no patient receiving placebo experienced such a reduction. However, in a prospective, double-blind, placebo-controlled study, no statistically significant reduction in the VAS score was observed in patients receiving 600 mg of mexiletine hydrochloride daily when compared with those receiving placebo. The role of mexiletine in the management of diabetic neuropathy remains to be established; pending further accumulation of data from well-designed studies, use of the drug should be limited to patients who do not respond to, or who cannot tolerate, more established therapies.