What is the recommended dosage and administration of Xylocard (lidocaine) for managing ventricular arrhythmias?

Xylocard (Lidocaine) Dosing for Ventricular Arrhythmias

For managing ventricular arrhythmias with lidocaine, administer an initial IV bolus of 1 mg/kg (maximum 100 mg), followed by a maintenance infusion of 20-50 μg/kg/min, with mandatory dose reductions in elderly patients, heart failure, cardiogenic shock, and hepatic dysfunction. 1

Initial Bolus Dosing

• Start with 1 mg/kg IV bolus (not exceeding 100 mg) 1
• If arrhythmia persists, give additional boluses of 0.5 mg/kg every 8-10 minutes up to a maximum cumulative dose of 4 mg/kg 1
• Patients requiring multiple boluses will likely need higher maintenance infusion rates (40-50 μg/kg/min) 1

Maintenance Infusion

• Standard maintenance rate: 20-50 μg/kg/min (equivalent to 1.4-3.5 mg/min in a 70 kg patient) 1
• Recent evidence in heart failure patients suggests 1 mg/min achieves the highest probability of therapeutic levels (78.6% within therapeutic range) compared to higher rates 2
• Target therapeutic blood levels: up to 5 μg/ml 1

Critical Dose Reductions Required

Heart Failure

• Reduce dosage significantly as the half-life increases from 1-2 hours to >4 hours 1
• In heart failure patients with ventricular arrhythmias, a maintenance rate of 1 mg/min is optimal, as higher rates increase supratherapeutic levels without improving efficacy 2

Cardiogenic Shock

• Substantial reduction mandatory as half-life can exceed 20 hours 1

Elderly Patients

• Reduce infusion rate due to increased toxicity risk 1

Hepatic Dysfunction

• Reduce dosage as lidocaine undergoes primary hepatic metabolism 1

Clinical Positioning in Treatment Algorithm

Lidocaine is not a first-line agent for ventricular arrhythmias:

• The European Society of Cardiology recommends lidocaine only for recurrent sustained VT or VF not responding to beta-blockers or amiodarone, or when amiodarone is contraindicated 1
• Treatment sequence: electrical cardioversion/defibrillation for unstable rhythms → beta-blockers → amiodarone → lidocaine 1
• Lidocaine is particularly indicated when ventricular arrhythmias are associated with acute myocardial ischemia or infarction 1

Monitoring Requirements

• Monitor blood pressure and cardiovascular status closely, especially in heart failure or hypotension 1
• Measure serum levels with prolonged infusions, high infusion rates, or neurologic changes 1
• Target therapeutic range: 1.5-5.0 μg/L 2

Critical Contraindications

Do not use lidocaine prophylactically in uncomplicated acute myocardial infarction 1, 3, 4

• Prophylactic use has not demonstrated mortality benefit and may increase risk of asystole 1
• The American College of Cardiology explicitly recommends against prophylactic administration 1
• Toxicity can occur in patients without infarction who receive prophylactic therapy 4

Common Pitfalls to Avoid

• Narrow therapeutic window: Lidocaine has a very limited optimal plasma level range where antiarrhythmic efficacy is maximized 5
• Avoid standard dosing in heart failure: The pharmacokinetics are dramatically altered, requiring lower maintenance rates 1, 2
• Do not overlook hepatic function: Primary hepatic metabolism means any liver dysfunction necessitates dose reduction 1
• Emergent adverse effects occur more frequently with prophylactic strategies (2.4% in prophylactic vs. 0% in selective use) 4