Amiodarone Dosage for Arrhythmia Treatment
The recommended dosage of amiodarone for arrhythmia treatment depends on the type of arrhythmia, with an initial loading dose of 400-600 mg daily in divided doses for 2-4 weeks, followed by a maintenance dose of 100-200 mg daily to minimize long-term adverse effects. 1
Dosing Regimens by Arrhythmia Type
Life-Threatening Arrhythmias (Intravenous Administration)
- Initial dose: 150 mg IV bolus over 10 minutes
- May repeat bolus in 10-30 minutes if necessary
- Follow with 1 mg/minute for 6 hours
- Then 0.5 mg/minute for 18 hours
- Convert to oral dosing when possible 1
Ventricular Arrhythmias (Oral Administration)
- Loading dose: 800-1,600 mg/day in divided doses until a total of 10 g has been given
- Maintenance dose: 200-400 mg/day 1
- Alternative regimen: 400-600 mg daily in divided doses for 2-4 weeks, then 100-200 mg daily 1
Atrial Fibrillation (Oral Administration)
- Loading dose: 600-800 mg/day in divided doses until a total of 10 g has been given
- Maintenance dose: 200 mg/day 1
- For inpatient setting: Up to 1,200 mg daily may be considered during loading phase 1
Transition from IV to Oral Therapy
When converting from IV to oral therapy, follow this protocol:
- IV treatment <1 week: 800-1,600 mg oral amiodarone daily
- IV treatment 1-3 weeks: 600-800 mg oral amiodarone daily
- IV treatment >3 weeks: 400 mg oral amiodarone daily 1
Important Considerations and Precautions
Dose-Related Adverse Effects
Amiodarone has numerous potential adverse effects that are often dose-related:
- Pulmonary toxicity (most serious)
- Thyroid dysfunction
- Hepatic toxicity
- Corneal deposits
- Peripheral neuropathy
- Photosensitivity
- Bradycardia and QT prolongation 1
Monitoring Requirements
Due to amiodarone's narrow therapeutic-toxic range, regular monitoring is essential:
- Baseline and periodic pulmonary function tests
- Liver function tests
- Thyroid function tests
- ECG monitoring
- Ophthalmologic examination 1
Drug Interactions
Amiodarone has significant drug interactions requiring dose adjustments:
- Reduce warfarin dose by 50%
- Reduce digoxin dose by 30-50%
- Use caution with other QT-prolonging medications
- Multiple interactions via CYP3A4, CYP2C8, P-glycoprotein 1
Pitfalls to Avoid
Using high maintenance doses unnecessarily: Lower maintenance doses (100-200 mg daily) are recommended to minimize long-term toxicity while maintaining efficacy 1
Inadequate loading: Without proper loading, therapeutic effects may be delayed for weeks to months due to amiodarone's long half-life 1
Failure to adjust doses for toxicity: Dose reduction is often required when side effects occur, as nearly all patients will develop some side effects at higher maintenance doses 2
Overlooking contraindications: Amiodarone should be used with caution or avoided in patients with:
- Sinus or AV conduction disease (without pacemaker)
- Inflammatory lung disease
- Thyroid dysfunction
- Severe hepatic dysfunction 1
Inadequate monitoring: Due to amiodarone's unique pharmacokinetics (half-life of approximately 30 days) and potential for toxicity, regular and comprehensive monitoring is essential 1
By following these dosing guidelines and monitoring protocols, amiodarone can be effectively used to treat various arrhythmias while minimizing the risk of serious adverse effects.