What is the recommended oral (by mouth) loading dose of amiodarone?

Oral Amiodarone Loading Dose

For ventricular arrhythmias, the recommended oral loading dose is 800 to 1,600 mg per day in divided doses until a total of 10 grams has been administered, followed by maintenance dosing of 200 to 400 mg per day. 1

Indication-Specific Dosing

Ventricular Arrhythmias (Inpatient Treatment)

• Loading phase: 800-1,600 mg/day in divided doses
• Total loading: Continue until 10 grams cumulative dose achieved
• Maintenance: 200-400 mg/day 1

Atrial Fibrillation (Inpatient or Outpatient)

• Loading phase: 600-800 mg/day in divided doses
• Total loading: Continue until 10 grams cumulative dose achieved
• Maintenance: 200 mg/day 1
• Note: Higher initial dosages or IV dosing may be used in unstable inpatients

Alternative High-Dose Loading Strategies

Research supports more aggressive oral loading regimens for faster conversion:

• Single loading dose approach: 25-30 mg/kg body weight as a single oral dose has demonstrated >85% conversion rates for recent-onset atrial fibrillation, with most conversions occurring after 6-8 hours 2
• Multi-day high-dose regimen: 50 mg/kg/day on days 1-3, then 30 mg/kg/day on days 4-5, then 600 mg twice daily on days 6-10 has been studied but showed no significant advantage over conventional dosing 3

Critical Dosing Considerations

Predictors of successful conversion include:

• Shorter duration of atrial fibrillation
• Smaller left atrial size
• Higher amiodarone dose 4

Important caveats:

• The frequency of adverse effects is directly related to total amiodarone exposure (dosage × duration), so use the lowest effective dose 1
• Most serious potential adverse effect is pulmonary toxicity, which occurs in approximately 1% annually with doses ≤300 mg/day 1
• Other significant toxicities include thyroid dysfunction, hepatotoxicity, bradycardia, QT prolongation, and GI upset 1

Transitioning from IV to Oral

When converting from IV to oral amiodarone, dosing depends on duration of IV therapy:

• <1 week IV: 800-1,600 mg/day oral
• 1-3 weeks IV: 600-800 mg/day oral
• >3 weeks IV: 400 mg/day oral 1

The guideline-recommended approach remains 800-1,600 mg/day in divided doses for ventricular arrhythmias and 600-800 mg/day for atrial fibrillation until 10 grams total is achieved, as this balances efficacy with safety and has the strongest evidence base from established clinical practice guidelines. 1