Amiodarone Loading Dose
For oral amiodarone loading, you need a total cumulative dose of 10 grams before transitioning to maintenance therapy. 1
Oral Loading Regimens
The specific daily dosing to reach this 10g target varies by indication:
For Ventricular Arrhythmias
- Start with 800-1600 mg per day in divided doses until 10g total has been administered 1
- Then transition to maintenance therapy of 200-400 mg per day 1
- At 1200 mg/day, this takes approximately 8-9 days to reach 10g 1
- At 800 mg/day, this takes approximately 12-13 days 1
For Atrial Fibrillation
- Use 600-800 mg per day in divided doses until 10g total has been given 1
- Then reduce to maintenance dose of 200 mg per day 1
- At 800 mg/day, this takes approximately 12-13 days 1
- At 600 mg/day, this takes approximately 16-17 days 1
Alternative Conservative Approach
- The American Heart Association also describes a more conservative regimen: 400-600 mg daily in divided doses for 2-4 weeks, followed by maintenance of 100-200 mg daily 1
- This approach takes longer but may reduce adverse effects 1
Inpatient High-Dose Loading
- Higher initial loading doses up to 1200 mg daily may be considered in an inpatient monitoring setting, though this increases the risk of adverse effects 1
- One studied protocol used 50 mg/kg/day for 3 days, then 30 mg/kg/day for 2 days, which was well tolerated in 15 of 16 patients 2
Intravenous Loading (24-Hour Protocol)
- The recommended IV loading is approximately 1000 mg over the first 24 hours 3
- Delivered as: 150 mg over 10 minutes, then 1 mg/min for 6 hours (360 mg), then 0.5 mg/min for 18 hours (540 mg) 4, 3
- Maximum 24-hour dose should not exceed 2.2 grams due to increased risk of severe hypotension and bradycardia 4
- After IV loading, continue maintenance infusion at 0.5 mg/min (720 mg/24 hours) 3
Critical Monitoring During Loading
Watch specifically for these adverse effects:
- Bradycardia and heart block (occurs in 4.9% with IV, 1-3% with oral) 5
- Hypotension (occurs in 16% with IV) 4
- QT prolongation (common but rarely causes torsades de pointes) 4
- Check baseline and serial ECGs, blood pressure, heart rate 1
- Monitor liver enzymes, thyroid function, and pulmonary symptoms 1
Important Caveats
The full antiarrhythmic effect takes days to weeks to develop despite adequate serum levels due to amiodarone's very long half-life and tissue distribution 1, 5. This means reaching the 10g cumulative dose is necessary but not sufficient—clinical effect lags behind the loading dose completion.
Dose reduction is frequently necessary due to side effects. In one study, the average dose had to be reduced from 572 mg/day at 45 days to 372 mg/day at 6 months due to frequent adverse effects 6. Side effects occurred in 93% of patients in that series 6.