Amiodarone Loading Dose Protocol
The recommended loading dose of intravenone amiodarone is 150 mg given over 10 minutes, followed by 1 mg/min infusion for 6 hours, then 0.5 mg/min infusion for the remainder of 24 hours, totaling approximately 1000 mg in the first day. 1, 2
Detailed Loading Dose Protocol
Initial Phase (First 24 Hours):
- Initial Rapid Load: 150 mg IV over 10 minutes
- Early Maintenance: 1 mg/min for 6 hours (360 mg)
- Later Maintenance: 0.5 mg/min for 18 hours (540 mg)
This provides approximately 1050 mg over the first 24 hours of therapy.
Administration Requirements:
- Use a volumetric infusion pump (mandatory)
- Preferably administer through a central venous catheter
- Use an in-line filter during administration
- Avoid concentrations >2 mg/mL for infusions longer than 1 hour unless using a central line (to prevent phlebitis)
- For infusions >2 hours, use glass or polyolefin bottles containing D5W
Indications for Loading Dose
- Hemodynamically stable monomorphic ventricular tachycardia
- Polymorphic VT with normal QT interval
- Stable irregular narrow complex tachycardia (atrial fibrillation)
- Stable regular narrow-complex tachycardia
- Rapid ventricular rate due to accessory pathway conduction
Breakthrough Arrhythmias
For breakthrough episodes of ventricular fibrillation or hemodynamically unstable ventricular tachycardia, repeat the initial load (150 mg over 10 minutes) 2.
Monitoring During Administration
- Continuous ECG monitoring
- Blood pressure monitoring every 5-15 minutes during initial infusion
- Watch for QT prolongation
- Monitor for bradycardia and heart block
- Observe for hypotension (most common adverse effect)
Important Precautions
- Maximum concentration: Do not exceed 3 mg/mL due to risk of phlebitis 3, 2
- Maximum infusion rate: Do not exceed 30 mg/min during initial loading 2
- Total daily dose: Should not exceed 2.2 g in 24 hours 1
- Duration: Maintenance infusion can be continued for 2-3 weeks if needed 2
Potential Adverse Effects
- Hypotension (most common, 26% of patients) 4
- Bradycardia (1-3% of patients) 3
- Phlebitis at infusion site
- QT prolongation (rarely leads to torsades de pointes)
- Heart block
Special Considerations
- For patients with hepatic dysfunction, consider dose reduction
- For patients with significant hypotension, slow the infusion rate
- For patients with bradycardia or AV block, slow or discontinue the infusion
Contraindications
- Hypersensitivity to amiodarone or iodine
- Cardiogenic shock
- Marked sinus bradycardia
- Second- or third-degree AV block without a functional pacemaker 2
Higher loading doses (up to 1000 mg/24 hours) have been shown to be more effective in suppressing life-threatening ventricular arrhythmias compared to lower doses (125 mg/24 hours) 4, but must be balanced against the risk of adverse effects, particularly hypotension.