What is the dosage and administration of Inj Xylocard (lidocaine) for treating ventricular arrhythmias?

Inj Xylocard (Lidocaine) Dosing for Ventricular Arrhythmias

For ventricular arrhythmias, administer an initial bolus of 1 mg/kg (maximum 100 mg) intravenously, followed by a continuous infusion at 20-50 μg/kg/min (1.4-3.5 mg/min for a 70 kg patient). 1

Initial Bolus Administration

• Give 1 mg/kg IV bolus (not exceeding 100 mg) over 2 minutes to rapidly achieve therapeutic blood levels 1, 2
• If arrhythmia persists, administer additional boluses of 0.5 mg/kg every 8-10 minutes as needed 1, 2
• Maximum total loading dose should not exceed 4 mg/kg 1, 2
• For ventricular fibrillation during cardiac arrest specifically, use a 100 mg bolus which may be repeated after 5-10 minutes 1

Maintenance Infusion

• Start continuous infusion at 20-50 μg/kg/min (equivalent to 1.4-3.5 mg/min in a 70 kg patient) immediately after the initial bolus 1, 2
• Patients requiring more than one bolus dose to suppress arrhythmias will likely need higher maintenance rates of 40-50 μg/kg/min 1, 2
• Target therapeutic blood levels up to 5 μg/ml 1, 2

Critical Timing Considerations

• A second bolus of 0.5 mg/kg may be needed 30-120 minutes after starting therapy due to transient subtherapeutic plasma concentrations, without changing the maintenance rate 1
• If arrhythmias recur after 8-10 hours of stable infusion, give another 0.5 mg/kg bolus and increase the maintenance infusion rate 1
• Reduce the infusion rate by 1 mg/min after 12-24 hours of therapy, as lidocaine half-life increases over time 1
• Simply increasing the maintenance infusion rate without an additional bolus results in very slow increases in plasma concentration (>6 hours to reach new plateau) 1

Mandatory Dose Reductions

Reduce dosage by approximately 50% in the following populations:

• Elderly patients over 70 years 1, 2
• Congestive heart failure (half-life increases to >4 hours, and can exceed 20 hours in cardiogenic shock) 1, 2
• Hepatic dysfunction (lidocaine is primarily metabolized by the liver) 1, 2
• Severe renal dysfunction 1
• Cardiogenic shock 1, 2

Clinical Indications

Lidocaine is indicated for:

• Ventricular premature beats that are frequent (>6/min), closely coupled (R on T), multiform, or occurring in short bursts of three or more in succession 1
• Ventricular tachycardia (sustained monomorphic VT not associated with angina, pulmonary edema, or hypotension) 1
• Ventricular fibrillation resistant to defibrillation 1
• Recurrent sustained VT or VF not responding to beta-blockers or amiodarone 2

Absolute Contraindications

• Complete heart block 1, 2
• Wide complex tachycardia attributable to accessory conduction pathways 1, 2
• Proven allergic or hypersensitivity reactions to lidocaine 1, 2

Toxicity Monitoring

Monitor closely for central nervous system symptoms:

• Early signs: nausea, drowsiness, perioral numbness, dizziness, confusion, slurred speech 1, 2
• Severe signs: muscle twitching, respiratory depression, double vision, tremor, altered consciousness, seizures 1

Monitor for cardiovascular effects:

• Bradycardia, sinus arrest, hypotension 1
• High concentrations may cause myocardial depression 1

Measure serum levels with prolonged or high infusion rates or if neurologic condition changes 1, 2

Duration of Therapy

• For prophylactic use, discontinue after the first 12-24 hours unless other therapeutic indications exist 1
• For treatment of ventricular arrhythmias, continue infusions for 6-24 hours, then reassess need for further management 1

Important Clinical Caveats

• Lidocaine has been shown to be less effective than amiodarone for ventricular arrhythmias 1
• Do NOT use prophylactically in uncomplicated acute myocardial infarction, as it has not shown mortality benefit and may increase risk of asystole 2, 3
• During cardiac arrest, bolus therapy should be the only administration method, given every 2-3 minutes as needed 1
• Response to lidocaine is delayed in patients with chronic ventricular arrhythmias compared to acute-onset arrhythmias; decisions about efficacy cannot be made accurately in the first 8 hours in chronic cases 4