mexiletine hydrochloride: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
mexiletine hydrochloride: clinical details
Prescribing considerations
- Treatment requires specialist oversight and assessment of ongoing symptomatic benefit.
- Obtain cardiology assessment and correct potassium or magnesium disturbances before initiation.
- Review hepatic and renal function, epilepsy, cardiac history, smoking status and clinically important interacting medicines.
- Counsel patients about arrhythmia symptoms and the need to disclose mexiletine before receiving new medicines or local anaesthetics.
Contraindications and cautions
- Hypersensitivity to mexiletine, an excipient or any local anaesthetic
- Ventricular tachyarrhythmia or significant atrioventricular or intraventricular conduction disease
- Current or previous myocardial infarction, symptomatic coronary artery disease, specified heart failure, atrial tachyarrhythmia or sinus-node dysfunction
- Concomitant torsades-inducing antiarrhythmics or narrow-therapeutic-index medicines specified in the product information
- Severe hepatic impairment; use is not recommended in severe renal impairment
Monitoring
- Baseline ECG, ambulatory rhythm monitoring, echocardiography and electrolytes, with early and continuing cardiac review adapted to individual risk
- Additional ECG assessment after treatment changes or introduction of medicines affecting conduction or mexiletine exposure
- Periodic electrolytes and clinical review for neurological, hepatic, hypersensitivity and cardiac adverse effects
- Relevant co-medicine concentrations or effects where CYP1A2 or OCT2 interactions are possible
Clinical pharmacology
Mexiletine produces use- and voltage-dependent sodium-channel blockade. It is well absorbed orally, metabolised mainly by hepatic CYP2D6 with CYP1A2 involvement, and partly excreted unchanged in urine; CYP2D6 phenotype, smoking and enzyme inhibitors or inducers can alter exposure.
Formulation and product differences
- The selected product is an orange-and-white hard gelatin capsule containing white powder.
- The capsule contains maize starch, colloidal anhydrous silica and magnesium stearate; its shell contains gelatin, iron oxide and titanium dioxide.
- It should be swallowed whole; suitability of opened capsules or feeding-tube administration has not been established.
mexiletine hydrochloride preparations and strengths
Capsule
Route: Oral
Strengths: 50 mg, 83 mg, 100 mg, 167 mg, 200 mg
mexiletine hydrochloride interactions
Check all prescribed, pharmacy and herbal products before starting them with mexiletine. Important interactions include:
Antiarrhythmics that can cause torsades de pointes
Medicines such as amiodarone, sotalol, quinidine, flecainide and propafenone can increase the risk of a potentially fatal rhythm disturbance and are contraindicated.
Other antiarrhythmics and medicines affecting cardiac conduction
Beta-blockers, verapamil, diltiazem, lidocaine and related medicines may increase cardiac adverse effects and generally require avoidance or exceptional specialist oversight.
Ciprofloxacin, fluvoxamine and other CYP1A2 or CYP2D6 inhibitors
These may raise mexiletine exposure, increasing adverse-effect risk and the need for clinical and ECG review.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.