Amiodarone Dosages for Stable Ventricular Tachycardia
For stable ventricular tachycardia (VT), the recommended oral amiodarone dosage is 800 to 1,600 mg per day in divided doses until a total of 10 g has been given, followed by a maintenance dose of 200 to 400 mg per day. 1
Intravenous Administration for Stable VT
For hemodynamically stable monomorphic VT requiring IV therapy, administer 150 mg over 10 minutes, which can be repeated if necessary, followed by a 1 mg/min infusion for 6 hours, then 0.5 mg/min infusion. Total dose over 24 hours should not exceed 2.2 g. 1
IV amiodarone onset of antiarrhythmic effect occurs rapidly, typically in less than 30 minutes. 1
For patients transitioning from IV to oral therapy, the oral dosing should be based on duration of IV therapy: 1
- IV therapy <1 week: 800-1,600 mg oral amiodarone daily
- IV therapy 1-3 weeks: 600-800 mg oral amiodarone daily
- IV therapy >3 weeks: 400 mg oral amiodarone daily
Oral Loading and Maintenance Dosing
Initial oral loading dose of 800-1,600 mg/day in divided doses is recommended to achieve therapeutic effect quickly. 1
Continue loading dose until a total cumulative dose of 10 g has been administered. 1
After loading, reduce to maintenance dose of 200-400 mg daily. 1
Higher maintenance doses (600-800 mg/day) may be more effective in preventing recurrences but carry increased risk of adverse effects. 2
Monitoring and Adverse Effects
The most serious potential adverse effect is pulmonary toxicity, which presents as subacute cough and progressive dyspnea with interstitial infiltrates on chest radiographs. 1
Common adverse effects include: 1
- Bradycardia and QT prolongation
- Gastrointestinal upset and constipation
- Rarely, torsades de pointes
Neurological effects such as tremor or ataxia occur in approximately 35% of patients on high-dose therapy and may require dose reduction. 3, 4
Frequency of adverse effects correlates with total amiodarone exposure (dosage and duration), so use the lowest effective dose possible. 1
Clinical Pearls and Pitfalls
Amiodarone has a very long half-life (20-47 days), which increases with age. Steady-state concentrations may not be achieved for weeks to months. 5
Elderly patients (>65 years) have lower clearance rates (about 100 mL/h/kg vs 150 mL/h/kg in younger patients) and may require lower doses. 5
Amiodarone is highly protein-bound (>96%) and has complex pharmacokinetics with extensive tissue distribution. 5
When using amiodarone for stable VT, close monitoring is essential due to its narrow therapeutic window and potential for serious adverse effects. 1
In patients with structural heart disease and life-threatening ventricular arrhythmias, implantable cardioverter-defibrillators (ICDs) should be considered as primary therapy, with amiodarone as an adjunct to reduce frequency of ICD shocks. 1