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mexiletine

C01BB02

Forms & Strengths

Oral capsules: 150 mg
Oral capsules: 200 mg
Oral capsules: 250 mg

Adult Dosing

Ventricular arrhythmias: Initial 200 mg every 8 hours with food; may adjust in 50-100 mg increments; max 1200 mg/day
Diabetic neuropathy (off-label): 150 mg to 300 mg twice daily

Pediatric Dosing

Safety and efficacy not established in children; use generally not recommended unless under specialist supervision

Indications

Life-threatening ventricular arrhythmias
Symptomatic diabetic peripheral neuropathy (off-label)
Non-dystrophic myotonias (off-label)

Mechanism of Action

Class IB antiarrhythmic agent that blocks voltage-gated sodium channels in cardiac myocardial tissue
Shortens the action potential duration and effective refractory period
Suppresses automaticity and decreases membrane responsiveness

Contraindications

Cardiogenic shock
Pre-existing second- or third-degree AV block without a functioning pacemaker
Hypersensitivity to mexiletine or local anesthetics of the amide type

Adverse Reactions

Dizziness, tremor, and lightheadedness
Nausea, vomiting, and dyspepsia
Proarrhythmia and exacerbation of arrhythmias
Elevated liver enzymes and severe drug-induced liver injury
Rash, including Stevens-Johnson syndrome (rare)

Drug Interactions

CYP1A2 and CYP2D6 inhibitors (e.g., cimetidine, fluvoxamine, quinidine) increase mexiletine plasma concentrations
CYP1A2 inducers (e.g., rifampin, tobacco smoke) decrease mexiletine levels
Additive cardiac depressant effects with other antiarrhythmic drugs
Potential to increase serum levels ofophylline and caffeine

Curated Content: Needs Vetting Before Put to Clinical Use