Cordarone (Amiodarone) Mode of Administration
Cordarone can be administered both intravenously and orally, with the route selection depending on clinical urgency—IV administration is reserved for life-threatening arrhythmias requiring immediate control, while oral administration is used for chronic maintenance therapy. 1
Intravenous Administration
Initial Dosing for Life-Threatening Arrhythmias
- Administer 150 mg IV bolus over 10 minutes for ventricular fibrillation or pulseless ventricular tachycardia unresponsive to defibrillation. 2, 3
- A second 150 mg IV bolus may be given if VF/pulseless VT persists. 3
- For cardiac arrest scenarios, the American College of Cardiology recommends 300 mg IV bolus when rhythm remains refractory to CPR, defibrillation, and epinephrine. 3
Standard 24-Hour Loading Protocol
- The recommended first 24-hour dose is approximately 1000 mg delivered as follows: 1
- Loading infusion: 150 mg over 10 minutes (15 mg/min)
- Followed by: 360 mg over the next 6 hours (1 mg/min)
- Maintenance: 540 mg over the remaining 18 hours (0.5 mg/min)
- After the first 24 hours, continue maintenance infusion at 0.5 mg/min (720 mg per 24 hours). 1
- Do not exceed an initial infusion rate of 30 mg/min. 1
Critical Administration Requirements
- Amiodarone must be delivered through a volumetric infusion pump—drop counter infusion sets can result in up to 30% underdosing. 1
- Administer through a central venous catheter whenever possible, as peripheral vein phlebitis occurs frequently with concentrations > 2 mg/mL. 4, 1
- Use an in-line filter during administration. 1
- For infusions longer than 1 hour, do not exceed concentrations of 2 mg/mL unless using a central venous catheter. 1
- Administer in glass or polyolefin bottles containing D5W for infusions exceeding 2 hours. 1
Contraindications and Monitoring for IV Use
- IV amiodarone is contraindicated in patients with bradycardia or second/third-degree heart block without a pacemaker. 4, 2
- IV administration causes bradycardia in 4.9% and hypotension in 16% of patients. 4
- If bradycardia or heart block develops, discontinue the infusion or reduce the rate immediately. 4
- Continuous ECG monitoring for heart rate, AV conduction abnormalities, and QT prolongation is mandatory during IV administration. 2
Oral Administration
Loading Dose Strategy
- The standard oral loading dose is 800-1,600 mg/day in divided doses. 3
- A common regimen is 600 mg twice daily for 7 days, followed by 600 mg daily thereafter. 5
- Continue loading until a total of 10 grams has been administered before transitioning to maintenance dosing. 3
Maintenance Dosing
- The maintenance dose should be 200-400 mg/day after completing the loading phase. 3
- Clinical experience demonstrates that doses above 600 mg/day are associated with significantly higher rates of side effects (93% of patients). 5
- Lower maintenance doses (200-300 mg/day) significantly decrease side effects while maintaining efficacy. 6
Transition from IV to Oral
- When transitioning from IV to oral therapy, clinical monitoring is essential, particularly for elderly patients. 1
- Monitor closely for breakthrough arrhythmias in the first 6 hours after IV discontinuation. 3
- The optimal transition dose depends on the duration of IV administration and cumulative dose already given. 1
Important Administration Caveats
Drug Interactions Requiring Dose Adjustments
- Reduce digoxin dose by 50% when starting amiodarone, as digoxin levels predictably double. 4
- Monitor prothrombin time/INR at least weekly during the first 6 weeks when co-administered with warfarin, as amiodarone significantly increases anticoagulation effects. 4
- Amiodarone inhibits CYP 2C9, CYP 2D6, and CYP 3A4 pathways, affecting metabolism of multiple medications including beta-blockers, calcium channel blockers, and narcotics. 4
Dietary Restriction
- Patients must not consume grapefruit or grapefruit juice during amiodarone therapy, as it inhibits CYP3A-mediated metabolism and increases plasma levels. 4, 1