Adult Dosing
Suppression of ventricular arrhythmia
- Start 200 mg PO tid or loading dose of 400 mg (if necessary)
- Adjust the dose at the intervals of 2-3 days in increments or decrements of 50 or 100 mg
- Usual dose: 200-300 mg PO tid with food or antacid (if arrhythmia is controlled)
- Start 400 mg PO tid, if no response achieved at 300 mg PO tid
- Max: 1200 mg/day
- q12 hrs dosage schedule
- Some patient can be shift to 12 hrs dosage regimen, if adequate response achieved with 300 mg PO tid
- Dose may be adjusted up to 450 mg (max) PO bid; carefully monitor the degree of suppression of ventricular ectopy
- Switching patient from another anti-arrhythmic agent to mexiletine
- Start 200 mg PO bid-qid after the last dose of quinidine sulfate
- Start 200 mg PO 3-6 hrs after the last dose of procainamide
- Start 200 mg PO 6-12 hrs after the last dose of disopryramide
- Start 200 mg PO 8-12 hrs after the last dose of tocainide
Pediatric Dosing
- Safety and effectiveness in pediatric patients have not been established
- Patients with second or third degree heart block with a functional ventricular pacemaker may be treated with mexiletine hydrochloride if they are monitored continuously
- Worsening of arrhythmias is associated with this drug. Patients with life-threatening arrhythmias such as sustained ventricular tachycardia are more susceptible. Exacerbation of the arrhythmias may occur in such patients on programmed electrical stimulation or on exercise provocation
- Carefully monitor patients with liver disease as hepatic impairment prolongs the elimination half-life of mexiletine
- Avoid concurrent drug therapy or dietary regimens which may markedly alter urinary pH during therapy
- SGOT elevation >3x ULN may occur. These events may occur in association with identifiable clinical events and therapeutic measures such as CHF, acute myocardial infarction, blood transfusions and other medications. These elevations are often asymptomatic and transient. Marked elevations of SGOT (> 1000 U/L) have occurred before death in patients with end-stage cardiac disease such as severe congestive heart failure, cardiogenic shock. Rare occasions of severe liver injury, including hepatic necrosis may occur. Carefully evaluate patients in whom an abnormal liver test has developed or those having signs of symptoms suggesting liver dysfunction. Consider discontinuation of therapy on detection of persistent or worsened elevation of hepatic enzymes
- Blood dyscrasias may occur in patients. On observation of significant hematologic changes evaluate carefully and if warranted consider discontinuation of therapy
- Convulsions may occur in patients with or without a prior history of seizures
Cautions: Use cautiously in
- Hepatic impairment
- Hepatic dysfunction secondary to CHF
- Pre-existing first degree AV block
- Pre-existing sinus node dysfunction
- Intraventricular conduction abnormalities
- Hypotension
- Severe CHF
- Seizure disorder
- Changes in smoking habit
Pregnancy Category:C
Breastfeeding: Maternal doses up to 600 mg do not cause any adverse effect to the breastfed infants, especially if the infant is older than 2 months. Due to lack of data, monitor breastfed infants if the drug is used during lactation and measure serum levels to rule out toxicity if there is a concern.
