What is the recommended dose of Amiodarone (antiarrhythmic medication) for the management of Atrial Fibrillation (AF)?

Recommended Amiodarone Dosing for Atrial Fibrillation

For the management of atrial fibrillation, amiodarone should be administered with a loading dose of 600-800 mg daily in divided doses until a total of 10 g has been given, followed by a maintenance dose of 200 mg daily. 1

Loading Regimens

• Oral loading:

  • 600-800 mg daily in divided doses to a total load of 10 g, then 200 mg daily for maintenance 2, 1
  • Alternative loading: 1000 mg daily for 1 week, followed by lower maintenance doses 2
  • Single high-dose loading (25-30 mg/kg) has shown >85% conversion rates in recent-onset AF but is less commonly used in practice 3, 4

• Intravenous loading (for more urgent situations):

  • 150 mg over 10 minutes, followed by 1 mg/min for 6 hours, then 0.5 mg/min for 18 hours 2, 1
  • Can transition to oral therapy after IV administration 1

Maintenance Dosing

• Standard maintenance dose: 200 mg daily 2, 1
• Dose range: 100-400 mg daily depending on response and side effects 2
• Low-dose approach: 200 mg daily or less may be effective with fewer side effects 2

Conversion from IV to Oral Therapy

• After IV therapy for less than 1 week: 800-1600 mg oral daily
• After IV therapy for 1-3 weeks: 600-800 mg daily
• After IV therapy for more than 3 weeks: 400 mg daily 1

Clinical Considerations

• Efficacy: Amiodarone is more effective than class I drugs, sotalol, or placebo for maintaining sinus rhythm in paroxysmal or persistent AF 2
• Special populations: Amiodarone is particularly useful in patients with structural heart disease (LVH, HF, CAD, previous MI) due to low proarrhythmic risk 2
• Dual benefit: Provides both rhythm control and rate control, often eliminating the need for additional rate-controlling medications 2
• Onset of action: Most conversions occur after 6-8 hours of therapy initiation 3

Monitoring and Adverse Effects

• Common adverse effects: Photosensitivity, GI upset, bradycardia, constipation 2, 1
• Serious adverse effects: Pulmonary toxicity, polyneuropathy, thyroid dysfunction, hepatic toxicity, eye complications 2, 1
• Monitoring recommendations:
  • ECG: Monitor for QT prolongation and bradycardia 1
  • Regular assessment of thyroid, liver, and pulmonary function 1
  • Reduce dose of concomitant digoxin and warfarin when starting amiodarone 2

Important Caveats

• Dose-dependent toxicity: Approximately 35-51% of patients experience adverse effects, often requiring dose reduction 1, 5
• Long half-life: Amiodarone has an elimination half-life of about 30 days (range 15-100 days), leading to delayed onset of full effect and prolonged activity after discontinuation 6
• Patient selection: Reserve amiodarone for highly symptomatic patients when rate-control strategies with anticoagulation are inadequate 1
• Outpatient initiation: Can usually be given safely on an outpatient basis, even in patients with persistent AF, due to minimal depression of myocardial function and low proarrhythmic potential 2

Dosing Algorithm

1. Initial assessment: Determine if patient requires immediate or elective cardioversion
2. For urgent cardioversion: Use IV loading protocol
3. For elective cardioversion: Begin oral loading protocol
4. After successful cardioversion: Transition to maintenance dose
5. Monitoring: Adjust dose based on clinical response and development of adverse effects 1, 7