What is the typical dose of oral amiodarone for treating arrhythmias?

Oral Amiodarone Dosing for Arrhythmias

For ventricular arrhythmias, start with an oral loading dose of 800-1,600 mg per day in divided doses until a cumulative total of 10 grams is reached, then reduce to a maintenance dose of 200-400 mg daily. 1, 2

Loading Dose Regimens by Arrhythmia Type

Ventricular Arrhythmias (VT/VF)

• Inpatient loading: 800-1,600 mg per day in divided doses until 10 g total cumulative dose is achieved 1, 2
• Outpatient loading: 600-800 mg per day in divided doses until 10 g total cumulative dose 3
• Alternative regimen: 400-600 mg daily in divided doses for 2-4 weeks 2
• The American Academy of Family Physicians supports the higher loading doses (800-1,600 mg/day) for ventricular arrhythmias given their life-threatening nature 1

Atrial Fibrillation

• Inpatient loading: 1,200-1,800 mg per day in divided doses until 10 g total, then 200-400 mg daily maintenance 3
• Outpatient loading: 600-800 mg per day in divided doses until 10 g total, then 200 mg daily maintenance 3, 2
• The lower maintenance dose (200 mg) for atrial fibrillation reflects the less aggressive approach needed compared to ventricular arrhythmias 2

Transitioning from IV to Oral Therapy

The oral dose depends on the duration of prior IV therapy: 1, 2

• IV therapy <1 week: Start 800-1,600 mg oral daily
• IV therapy 1-3 weeks: Start 600-800 mg oral daily
• IV therapy >3 weeks: Start 400 mg oral daily

This stepwise reduction accounts for amiodarone's extensive tissue accumulation during prolonged IV administration 1, 2

Maintenance Dosing Strategy

• Standard maintenance: 200-400 mg daily after loading phase complete 3, 1, 2
• Dose reduction is frequently necessary due to side effects—in one study, the mean dose decreased from 572 mg/day at 45 days to 372 mg/day at 6 months 4
• Use the lowest effective maintenance dose to minimize toxicity, as adverse effects correlate directly with cumulative amiodarone exposure 1

Critical Monitoring Parameters

During Loading Phase

• Watch for bradycardia, QT prolongation, hypotension, and heart block 2
• The full antiarrhythmic effect may take days to weeks despite adequate serum levels due to amiodarone's extremely long half-life (14-58 days after chronic therapy) 2, 5
• Gastrointestinal side effects (especially constipation) occur in the majority of patients 4

Long-Term Monitoring

• Pulmonary toxicity is the most serious concern—presents as subacute cough and progressive dyspnea with interstitial infiltrates 1
• Thyroid dysfunction, hepatic toxicity, and corneal microdeposits require ongoing surveillance 2, 4
• In one series, 93% of patients developed side effects, with 19% requiring discontinuation 4

Common Pitfalls to Avoid

• Do not use standard 600 mg daily maintenance doses routinely—this was associated with near-universal side effects in early studies, necessitating dose reductions 4
• Do not expect immediate effect—amiodarone's onset is delayed compared to Class IC agents, with maximal effect often requiring weeks 3
• Avoid in patients with structural heart disease requiring rapid cardioversion—Class IC drugs work faster for acute conversion, though amiodarone is safer in heart failure 3
• Remember drug interactions—particularly with warfarin and digoxin, which require dose adjustments 2