What is the recommended oral loading dose of amiodarone?

Recommended Oral Loading Dose of Amiodarone

The recommended oral loading dose of amiodarone is 400-600 mg daily in divided doses for 2-4 weeks, followed by a maintenance dose of 100-200 mg daily. 1

Initial Loading Dose Regimen

• For ventricular arrhythmias, start with 800-1600 mg per day in divided doses until a total of 10 g has been administered, then transition to maintenance therapy of 200-400 mg per day 1, 2
• For atrial fibrillation, use 600-800 mg per day in divided doses until a total of 10 g has been given, then reduce to a maintenance dose of 200 mg per day 1, 2
• 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

Alternative Loading Protocols

• Some clinicians use a more aggressive loading approach of 50 mg/kg per day for 3 days, followed by 30 mg/kg per day for 2 days, then maintenance therapy of 300-400 mg twice daily 3
• Another approach is 800 mg/day for 6 weeks followed by 600 mg/day maintenance, though this higher maintenance dose is associated with significant toxicity in approximately 50% of patients 4
• A single oral loading dose of 25-30 mg/kg has been used for recent-onset atrial tachyarrhythmias with a 64.4% success rate for conversion to sinus rhythm within 24 hours 5

Important Considerations

• Monitoring is essential during loading: Watch for bradycardia, QT prolongation, hypotension, and heart block 1, 2
• Amiodarone has a very long half-life, and the full antiarrhythmic effect may take days to weeks to develop despite adequate serum levels 2
• The dose should be reduced if side effects occur; in one study, the dose was reduced from 572 ± 283 mg per day at 45 days to 372 ± 174 mg per day at 6 months due to adverse effects 6
• Side effects are common (occurring in up to 93% of patients), with gastrointestinal effects, corneal microdeposits, neurologic effects (tremor, ataxia), and pulmonary toxicity being most concerning 6

Transitioning from IV to Oral Amiodarone

• For patients receiving IV amiodarone for less than one week, transition to 800-1600 mg oral amiodarone per day 1, 2
• For patients receiving IV amiodarone for 1-3 weeks, transition to 600-800 mg oral amiodarone per day 2
• For patients receiving IV amiodarone for more than 3 weeks, transition to 400 mg oral amiodarone per day 2

Pitfalls to Avoid

• Do not drink grapefruit juice during treatment with oral amiodarone as it inhibits CYP3A-mediated metabolism, resulting in increased plasma levels 7
• Be aware of significant drug interactions, particularly with warfarin (reduce warfarin dose by 50%) and digoxin (reduce digoxin dose by 30-50%) 1
• Avoid coadministration with other QT-prolonging medications without expert consultation 1
• Monitor for pulmonary toxicity, thyroid dysfunction, and hepatic toxicity during long-term therapy 1

By following these guidelines, the oral loading dose of amiodarone can be safely administered to achieve therapeutic effects while minimizing the risk of adverse events.