What are the recommended doses of lidocaine and procainamide (anti-arrhythmic medications) for a 70kg person?

Recommended Lidocaine and Procainamide Dosing for a 70kg Person

For a 70kg person, lidocaine should be administered as an initial IV bolus of 1-1.5 mg/kg (70-105mg), followed by a maintenance infusion of 20-50 μg/kg/min (1.4-3.5 mg/min), while procainamide should be given as an IV loading dose of 10-15 mg/kg (700-1050mg) at 20 mg/min, followed by a maintenance infusion of 1-4 mg/min. 1, 2

Lidocaine Dosing

Initial Bolus

• 1-1.5 mg/kg (70-105mg for a 70kg person) 2, 1
• In cardiac arrest: 100mg bolus, repeatable every 2-3 minutes as needed 2, 1
• Additional boluses of 0.5-0.75 mg/kg (35-52.5mg) can be given every 5-10 minutes if needed 2
• Maximum cumulative bolus dose: 3 mg/kg (210mg for a 70kg person) 2

Maintenance Infusion

• 20-50 μg/kg/min (1.4-3.5 mg/min for a 70kg person) 1
• For patients with heart failure: reduce to 1 mg/min maximum 3
• A second bolus of 0.5 mg/kg (35mg) may be needed 30-120 minutes after initiation due to transient subtherapeutic plasma concentrations 2, 1

Special Considerations

• Reduce dose after 24-48 hours by 1 mg/min due to increased half-life 2, 1
• Target therapeutic range: 2-4 mg/L (or < 5 μg/ml) 1
• Reduce infusion rates in elderly patients (>70 years), patients with heart failure, cardiogenic shock, or hepatic dysfunction 2, 1

Procainamide Dosing

Loading Dose

• 10-15 mg/kg (700-1050mg for a 70kg person) 2
• Administered at a rate of 20 mg/min (over 35-52.5 minutes for a 70kg person) 2
• Alternative regimen: 1-2 mg/kg over 5 minutes to a cumulative dose of approximately 1,000 mg 1

Maintenance Infusion

• 1-4 mg/min 2
• Alternative regimen: 20-80 μg/kg/min (1.4-5.6 mg/min for a 70kg person) 1

Comparative Efficacy

Procainamide has been shown to be superior to lidocaine in terminating ventricular tachycardia. In clinical studies, procainamide terminated 12 of 15 VT episodes compared to only 3 of 14 for lidocaine 4. Another study showed procainamide suppressed induction of sustained VT in 52% of patients, while lidocaine was ineffective in all cases 5.

Monitoring and Safety

• During lidocaine infusion: continuous ECG monitoring with blood pressure checks every 5 minutes for the first 15 minutes 1
• Check lidocaine blood levels at 4 hours, 24 hours, and daily thereafter if infusion continues 1
• Watch for signs of lidocaine toxicity: perioral tingling, tinnitus, light-headedness, restlessness, nausea, drowsiness, confusion, slurred speech, and muscle twitching 2, 1
• Procainamide may cause proarrhythmia, including torsades de pointes, especially in patients with renal insufficiency 2

Clinical Decision Algorithm

1. For initial management of ventricular arrhythmias, start with lidocaine (faster onset)
2. If lidocaine fails, switch to procainamide (higher efficacy but slower onset)
3. For patients with heart failure, use reduced lidocaine dosing (1 mg/min maximum)
4. For patients with renal insufficiency, use lidocaine preferentially over procainamide
5. For patients with hepatic dysfunction, reduce lidocaine dosing and consider procainamide

Remember that both medications significantly affect intraventricular conduction in a rate-dependent manner, with procainamide causing greater QRS prolongation than lidocaine at all heart rates 6.