Amiodarone Dosing Regimen
The recommended dosing regimen for amiodarone includes an initial loading dose of 1000 mg over the first 24 hours for IV administration, followed by a maintenance infusion of 0.5 mg/min (720 mg/24 hours), while oral therapy typically starts with 600-800 mg daily for 7 days followed by maintenance doses of 200-400 mg daily. 1, 2, 3
Intravenous (IV) Amiodarone Dosing
Initial Loading Phase (First 24 Hours)
- Total dose: 1000 mg over 24 hours administered as follows 1:
- First rapid infusion: 150 mg over 10 minutes
- Early maintenance: 1 mg/min for 6 hours (360 mg)
- Later maintenance: 0.5 mg/min for remaining time (490 mg)
Maintenance Phase (After First 24 Hours)
- Continue at 0.5 mg/min (720 mg/24 hours)
- Use concentration of 1-6 mg/mL
- For concentrations >2 mg/mL, use central venous catheter 1
Breakthrough Episodes
- For breakthrough VF or unstable VT: 150 mg supplemental infusion in 100 mL D5W over 10 minutes
- Maintenance infusion rate may be increased for effective arrhythmia suppression 1
Important Administration Notes
- Must be delivered via volumetric infusion pump
- Use in-line filter during administration
- Preferably administer through dedicated central venous catheter
- Do not exceed initial infusion rate of 30 mg/min
- Maintenance infusion can continue for 2-3 weeks regardless of age, renal function, or LV function 1
- Concentrations >3 mg/mL associated with high incidence of phlebitis 1
Oral Amiodarone Dosing
Loading Phase
- 600-800 mg daily for 7 days (total 4.2-5.6g) 3
- Can be given in divided doses
Maintenance Phase
- 200-400 mg daily 3
- Lower doses (200 mg) may be effective with fewer side effects
- Adjust based on patient-specific factors (age, renal function, hepatic function)
Conversion from IV to Oral
Based on duration of previous IV therapy 3:
- <1 week of IV therapy: 800-1600 mg daily oral dose
- 1-3 weeks of IV therapy: 600-800 mg daily oral dose
3 weeks of IV therapy: 400 mg daily oral dose
Monitoring Requirements
During Therapy
- ECG monitoring for QT prolongation and bradycardia
- Blood pressure monitoring (watch for hypotension)
- Electrolytes: maintain potassium and magnesium >4.0 mEq/L 3
Long-term Monitoring
- Thyroid function tests every 6 months
- Liver function tests every 6 months
- Pulmonary function tests if respiratory symptoms develop
- Ophthalmologic examination if visual symptoms occur 3
Important Considerations
Drug Interactions
- Amiodarone inhibits multiple CYP450 enzymes and P-glycoprotein
- Significant interactions with:
- Warfarin: reduced clearance, monitor INR closely
- Digoxin: levels may double, reduce digoxin dose
- Statins: limit simvastatin to 20 mg daily 3
Common Side Effects
- Bradycardia (more common in women)
- Hypotension (especially during loading)
- QT prolongation
- Gastrointestinal upset
- Photosensitivity
- Pulmonary toxicity
- Thyroid dysfunction 3
Contraindications
- Severe sinus node dysfunction
- AV block (without pacemaker)
- Cardiogenic shock
- Severe bradycardia 3
Pitfalls to Avoid
- Higher than recommended infusion rates can cause hepatocellular necrosis and acute renal failure 1
- Do not use evacuated glass containers for admixing (may cause precipitation)
- Amiodarone adsorbs to PVC tubing, which affects dosing
- Avoid abrupt discontinuation; taper due to long half-life (average 58 days) 3
- Monitor closely for drug interactions, especially with warfarin and digoxin
Amiodarone shows considerable interindividual variation in response, requiring close monitoring and dose adjustments to balance efficacy against side effects 1, 3.