Oral Amiodarone Loading Dose for Arrhythmia Management
For arrhythmia management, the recommended oral loading dose of amiodarone is 600-800 mg per day in divided doses until a total of 10 g has been given for atrial fibrillation, and 800-1,600 mg per day in divided doses until a total of 10 g has been given for ventricular arrhythmias. 1
Specific Loading Dose Regimens by Arrhythmia Type
For Ventricular Arrhythmias
- Inpatient setting: 800-1,600 mg per day in divided doses until a total of 10 g has been administered 1
- After loading, transition to maintenance dose of 200-400 mg per day 1
- Common approach: 600 mg twice daily for 7 days (as demonstrated in clinical research) 2
For Atrial Fibrillation
- Outpatient setting: 600-800 mg per day in divided doses until a total of 10 g has been administered 1
- Inpatient setting: May use higher initial dosage or IV dosing in unstable patients 1
- After loading, transition to maintenance dose of 200 mg per day 1
Converting from IV to Oral Amiodarone
When transitioning from IV to oral amiodarone, the loading dose should be adjusted based on duration of prior IV therapy:
- IV therapy <1 week: Use 800-1,600 mg oral amiodarone daily
- IV therapy 1-3 weeks: Use 600-800 mg oral amiodarone daily
- IV therapy >3 weeks: Use 400 mg oral amiodarone daily 1
Monitoring During Loading Phase
During the loading phase, close monitoring is essential due to potential adverse effects:
- Cardiovascular: Bradycardia, QT prolongation, heart block (1-3% of patients) 3
- Gastrointestinal: Nausea, constipation (common) 1, 3
- Neurological: Tremor, ataxia (can occur in 20-40% of patients) 3
Important Considerations and Caveats
- Dose reduction: The loading dose often needs to be reduced due to side effects. Research shows dose reduction from 572 mg/day at 45 days to 372 mg/day at 6 months is common 2
- Toxicity risk: Side effects are common (occurring in up to 93% of patients in some studies) and may require dose adjustment 2
- Therapeutic effect timing: While IV amiodarone has rapid onset (<30 minutes), oral amiodarone has delayed onset and may take days to weeks for full effect 1
- Maintenance dose: After loading, use the lowest effective maintenance dose (often 200 mg/day) to minimize adverse effects 3
Alternative Loading Approaches
Some research supports higher loading doses for faster effect:
- One study used 50 mg/kg/day for 3 days, then 30 mg/kg/day for 2 days, followed by maintenance of 300-400 mg twice daily with good tolerance 4
- Combined IV and oral loading may shorten time to optimal arrhythmia control compared to oral loading alone 5
The loading dose regimen should be selected based on the urgency of the clinical situation, with higher doses and inpatient monitoring for life-threatening arrhythmias, and more conservative approaches for chronic management.