Mexiletine Hydrochloride Clinigen Healthcare (Mexiletine Hydrochloride)

Mexiletine Hydrochloride is a Class IB antiarrhythmic that modulates cardiac sodium channels to manage ventricular rhythm disorders.

• Ventricular arrhythmias: suppresses abnormal electrical activity arising from the ventricles.
• Ventricular tachycardia: reduces the frequency and duration of rapid ventricular beats.
• Post‑myocardial infarction ventricular ectopy: diminishes premature ventricular contractions after a heart attack.

• Mexiletine Hydrochloride blocks fast sodium channels in cardiac myocytes, decreasing the influx of sodium during phase 0 of the cardiac action potential. This shortens the action potential duration and refractory period, stabilising myocardial excitability and preventing the propagation of abnormal ventricular impulses characteristic of Class IB antiarrhythmic activity.

Adverse reactions may vary in frequency and severity.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Dizziness: sensation of light‑headedness or unsteadiness.
• Tremor: involuntary shaking, often of the hands.
• Headache: mild to moderate pain in the head region.
• Fatigue: generalized feeling of tiredness.
• Gastrointestinal discomfort: abdominal cramping or dyspepsia.

Serious or Rare Side Effects

• Worsening cardiac arrhythmia: paradoxical increase in ventricular ectopy.
• Severe hypotension: marked drop in blood pressure.
• Allergic reactions: rash, pruritus, or anaphylaxis.
• Liver enzyme elevation: signs of hepatic stress.
• Blood dyscrasias: neutropenia or agranulocytosis.
• Pulmonary toxicity: interstitial lung changes or dyspnea.

Careful assessment and monitoring are required before and during therapy.

• Cardiac monitoring: obtain baseline ECG and monitor for new arrhythmias.
• Renal impairment: adjust dose or avoid use in severe renal dysfunction.
• Hepatic impairment: consider dose reduction in patients with liver disease.
• Concomitant antiarrhythmics: avoid combining with other Class I agents.
• Electrolyte disturbances: correct potassium or magnesium abnormalities before initiation.
• Pregnancy safety: use only if potential benefit justifies potential risk to the fetus.
• Store at ambient temperature: keep in the original container, protect from moisture and direct sunlight.

Mexiletine Hydrochloride may interact with several drug classes.

Major Interactions (Avoid)

• Other Class I antiarrhythmics (e.g., lidocaine, procainamide): additive sodium‑channel blockade.
• Strong CYP2D6 inhibitors (e.g., quinidine, fluoxetine): increase mexiletine plasma levels.
• Monoamine oxidase inhibitors: risk of severe hypotension.
• Drugs that prolong QT interval (e.g., sotalol): potential for torsades de pointes.
• Certain anti‑seizure medications (e.g., carbamazepine): may reduce mexiletine efficacy.

Moderate Interactions (Monitor Closely)

• Beta‑blockers: may enhance bradycardic effects.
• Diuretics causing electrolyte loss: increase risk of arrhythmia.
• ACE inhibitors or ARBs: monitor blood pressure.
• Selective serotonin reuptake inhibitors: observe for CNS side effects.
• Anticoagulants (e.g., warfarin): watch for altered bleeding risk.