Mexiletine

It is chemically & pharmacologically similar to lidocaine; a local anaesthetic, active antiarrhythmic by oral route.Mexiletine is an antiarrhythmic medication that belongs to the class of drugs known as class Ib antiarrhythmics. It works by stabilizing the electrical activity of the heart, specifically the cardiac cell membranes, to prevent abnormal heart rhythms (arrhythmias), particularly those arising from the ventricles.

Indications

Post infarction ventricular arrhythmias. Mexiletine is primarily indicated for the treatment of ventricular arrhythmias, which are abnormal heart rhythms originating in the lower chambers of the heart (ventricles). It is often used when other antiarrhythmic medications have not been effective or are not well-tolerated.

Dosage

Initially 400-600 mg followed after 2 hrs by maint. dose of 200-250 mg 3-4 times daily. I.V. initial : Slow i.v. of 200-250 mg at 25 mg/min followed by i.v. infusion of 1 mg/min over 1 hr. Maint 0.5 mg/min.

Contra-Indications

Bradycardia, hypotension, conduction defects. Sinus node dysfunction.

Special Precautions

B.P., ECG monitoring must during therapy. Renal or hepatic impairment. Paediatrics: Dose reduction necessary. Pregnancy: Not recommended unless the potential benefits outweigh the potential risks. Lactation: Present in breast milk and may effect the infant. Hence contraindicated. Elderly: To be used with caution.

Side Effects

Nausea Vomiting Dizziness Lightheadedness Tremor Headache Blurred vision Serious side effects are less common but can include: Cardiac arrhythmias Changes in blood pressure Liver problems Allergic reactions (rash, itching, swelling, severe dizziness) Mental/mood changes (e.g., confusion, anxiety)

Drug Interactions

Ammonium chloride and phenytoin increase excretion rate of the drug. Sodium bicarbonate reduces excretion. Opiates delay absorption. Useful combinations with betablockers.