What is the dose of lidocaine (antiarrhythmic medication) for ventricular tachycardia (VT)?

Lidocaine Dosing for Ventricular Tachycardia

For stable VT, administer lidocaine as an initial IV bolus of 1 to 1.5 mg/kg (typically 75-100 mg), followed by additional boluses of 0.5 to 0.75 mg/kg every 5-10 minutes as needed up to a total of 3 mg/kg, then maintain with a continuous infusion of 1-4 mg/min (30-50 mcg/kg/min). 1

Initial Bolus Dosing

• Give 1 to 1.5 mg/kg IV bolus (not exceeding 100 mg) as the initial dose for ventricular tachycardia 1, 2
• For stable VT specifically, the British Journal of Sports Medicine recommends 50 mg IV over 2 minutes, which can be repeated every 5 minutes to a total dose of 200 mg 2
• Additional boluses of 0.5 to 0.75 mg/kg can be given every 5-10 minutes if the initial bolus is insufficient 1
• The maximum total bolus dose should not exceed 3 to 4 mg/kg 1, 3

Maintenance Infusion

• After successful bolus therapy, start a maintenance infusion at 1-4 mg/min (or 30-50 mcg/kg/min) 1
• The American College of Cardiology specifies a range of 20-50 mcg/kg/min (1.4-3.5 mg/min in a 70 kg patient) 2, 3
• Patients requiring multiple boluses may need higher maintenance doses (40-50 mcg/kg/min) to maintain therapeutic effect 3

Dose Adjustments for Special Populations

• Reduce doses significantly in patients with heart failure, cardiogenic shock, or acute myocardial infarction, as lidocaine clearance is substantially decreased 1, 4
• In heart failure, lidocaine's half-life increases to >20 hours (compared to 1-2 hours normally), requiring appropriate dose reduction 4
• Reduce the infusion rate after 24-48 hours as the half-life of lidocaine increases over time 3
• The American College of Cardiology recommends reducing the dose by 1 mg/min at 12 hours, but at least by 24 hours 3

Important Clinical Context

Lidocaine is considered second-line therapy for monomorphic VT, as it is less effective than procainamide, sotalol, and amiodarone at terminating VT 1. A head-to-head trial demonstrated that procainamide terminated VT in 80% of cases (38 of 48 episodes) compared to only 19% with lidocaine (6 of 31 episodes) 5.

When to Use Lidocaine

• Lidocaine remains appropriate as first-line therapy in the acute MI setting when treatment is indicated for VT or VF 1
• It is particularly useful for VT thought to be related to myocardial ischemia 2
• For pulseless VT/VF during cardiac arrest, give a 100 mg bolus that may be repeated every 2-3 minutes as needed 3

When to Choose Alternative Agents

• For unstable VT with pulse, immediate synchronized DC cardioversion (100J, 200J, 360J) is the primary intervention, not pharmacologic therapy 2
• Amiodarone (150 mg IV over 10 minutes) is indicated for VT refractory to lidocaine 1, 2
• Consider procainamide as it has superior efficacy for terminating sustained monomorphic VT 5

Monitoring for Toxicity

• Watch for CNS symptoms: nausea, drowsiness, perioral numbness, dizziness, confusion, slurred speech, muscle twitching, seizures, and respiratory depression 3, 4
• Monitor for cardiovascular effects: bradycardia, sinus arrest, and hypotension 3, 4
• Lidocaine depresses myocardial contractility, requiring careful monitoring especially in hemodynamically compromised patients 2

Common Pitfalls to Avoid

• Do not use standard doses in patients with heart failure or shock without significant reduction—this is a critical error that can lead to toxicity 1, 4
• Increasing the maintenance infusion without an additional bolus results in a very slow increase in plasma concentration (>6 hours to reach new plateau) 3
• Do not rely on lidocaine as first-line therapy for stable VT in non-MI settings—procainamide or amiodarone are more effective 1, 5
• Response to lidocaine in patients with chronic VPBs is delayed compared to acute-onset arrhythmias; accurate assessment of response cannot be made in the first 8 hours 6