Dosing of Procainamide and Lidocaine for Ventricular Tachycardia in a 70kg Patient
For a 70kg patient with ventricular tachycardia, procainamide should be administered at 20-50 mg/min until arrhythmia suppression, hypotension occurs, QRS duration increases >50%, or maximum dose of 17 mg/kg (1190 mg) is reached; lidocaine should be given at 1-1.5 mg/kg (70-105 mg) IV initially, followed by 0.5-0.75 mg/kg every 5-10 minutes if needed, up to a maximum of 3 mg/kg total. 1
Procainamide Dosing for VT
Loading Dose:
- 20-50 mg/min IV infusion 1
- For a 70kg patient, maximum dose: 17 mg/kg = 1190 mg 1, 2
- Alternative approach: 100 mg every 5 minutes until arrhythmia is controlled 1, 2
- Continue until one of these endpoints is reached:
- Arrhythmia suppression
- Hypotension develops
- QRS duration increases by 50%
- Maximum dose is reached
Maintenance Infusion:
Lidocaine Dosing for VT
Loading Dose:
- Initial dose: 1-1.5 mg/kg IV 1
- For a 70kg patient: 70-105 mg IV
- Can repeat if required at 0.5-0.75 mg/kg IV (35-52.5 mg) every 5-10 minutes 1
- Maximum cumulative dose: 3 mg/kg (210 mg for a 70kg patient) 1
Maintenance Infusion:
- 1-4 mg/min (30-50 mcg/kg/min) 1
Clinical Considerations
Efficacy Comparison
- Procainamide has shown superior efficacy compared to lidocaine for terminating sustained monomorphic VT 3, 4
- Studies show procainamide terminates VT in approximately 80% of cases versus only 20% for lidocaine 4
Monitoring During Administration
- Continuous cardiac monitoring is essential
- Monitor blood pressure frequently during administration
- Watch for QRS widening, which may indicate toxicity
- Be prepared for potential hypotension with procainamide 1
Contraindications
- Procainamide: Avoid in patients with QT prolongation and CHF 1
- Lidocaine: Use with caution in patients with hepatic dysfunction or heart block 5
Side Effects
- Procainamide: Bradycardia, hypotension, torsades de pointes 1
- Lidocaine: Slurred speech, altered consciousness, seizures, bradycardia 1
Remember that if the patient becomes hemodynamically unstable at any point during medication administration, immediate synchronized cardioversion is indicated rather than continuing pharmacological management.