What is the recommended loading and maintenance dose of amiodarone for arrhythmia treatment?

Amiodarone Loading and Maintenance Dosing for Arrhythmia Treatment

For arrhythmia treatment, 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

Oral Dosing Regimens

Standard Oral Loading Protocol

• Initial loading: 400-600 mg daily in divided doses for 2-4 weeks 1
• Maintenance: 100-200 mg daily 1

Alternative More Aggressive Oral Loading Protocol

• Week 1: 800 mg daily in divided doses
• Week 2: 600 mg daily in divided doses
• Week 3-6: 400 mg daily in divided doses
• Maintenance: 200 mg daily 1

Traditional 10g Loading Protocol

• 800 mg daily in divided doses for 1 week
• 600 mg daily in divided doses for 1 week
• 400 mg daily in divided doses for 4-6 weeks
• Total loading dose: approximately 10 g 1
• Maintenance: 200-400 mg daily 2

Intravenous Dosing for Emergency Situations

For life-threatening arrhythmias requiring immediate intervention:

• 150 mg IV bolus over 10 minutes (may be repeated in 10-30 minutes if necessary)
• Then 1 mg per minute for 6 hours
• Then 0.5 mg per minute for 18 hours
• Then reduce IV dosage or convert to oral dosing when possible 2

Transitioning from IV to Oral Therapy

When switching from IV to oral amiodarone, use the following guidelines based on duration of IV therapy:

• IV use <1 week: 800-1600 mg oral amiodarone daily
• IV use 1-3 weeks: 600-800 mg oral amiodarone daily
• IV use >3 weeks: 400 mg oral amiodarone daily 2, 1

Indication-Specific Dosing

Ventricular Arrhythmias

• Oral inpatient treatment: 800-1600 mg per day in divided doses until a total of 10 g has been given
• Then maintenance: 200-400 mg per day 2

Atrial Fibrillation

• Oral inpatient or outpatient treatment: 600-800 mg per day in divided doses until a total of 10 g has been given
• Then maintenance: 200 mg per day 2

Monitoring Requirements

• ECG monitoring during loading phase for QT prolongation, bradycardia, and heart block
• Monitor for hypotension, especially in patients with compromised cardiac function
• Continuous monitoring of ECG and vital signs during IV administration 1
• Regular follow-up should include:
  • Thyroid studies
  • Liver transaminase levels
  • Directed physical examination every 6 months
  • Chest radiograph and pulmonary function tests as needed
  • Ophthalmologic examination if visual symptoms develop 1

Important Considerations and Precautions

• Amiodarone has a narrow therapeutic-toxic range and a prolonged loading phase 2
• Dose adjustments are often needed due to side effects - 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 3
• Amiodarone has a very long half-life (approximately 30 days, range 15-100 days), which affects both the loading period and persistence of effects after discontinuation 4
• When co-administered with warfarin, reduce warfarin dose by 50% 1
• When co-administered with digoxin, reduce digoxin dose by 30-50% 1

Common Side Effects to Monitor

• Gastrointestinal: constipation, nausea, anorexia
• Neurological: tremor, ataxia
• Pulmonary: interstitial infiltrates (5% of patients)
• Ophthalmologic: corneal microdeposits, visual halos or blurring
• Thyroid dysfunction
• Skin discoloration 3, 5

The dosing of amiodarone requires careful consideration of the arrhythmia being treated, the urgency of the situation, and the patient's tolerance of side effects. Regular monitoring is essential to balance efficacy with toxicity.