What is the appropriate dosage of Amiodarone (amiodarone) for atrial fibrillation (Afib) with rapid ventricular response (RVR)?

From the Guidelines

For atrial fibrillation with rapid ventricular response (AFib with RVR), amiodarone should be administered as a 150 mg IV bolus over 10 minutes, followed by a continuous infusion of 1 mg/minute for 6 hours, then 0.5 mg/minute for the remaining 18 hours, with a total dose over 24 hours not exceeding 2.2 g, as recommended by the 2010 American Heart Association guidelines 1. This dosing regimen is supported by the most recent and highest quality study, which prioritizes patient outcomes in terms of morbidity, mortality, and quality of life.

Key Considerations

• The initial IV bolus of 150 mg over 10 minutes can be repeated if necessary, and the infusion rates can be adjusted based on patient response and tolerance.
• It is essential to monitor patients for potential side effects, including bradycardia, hypotension, and phlebitis, as outlined in the guidelines 1.
• Amiodarone's mechanism of action involves blocking multiple ion channels in cardiac tissue, which helps control heart rate and restore normal rhythm.
• Important considerations during treatment include monitoring for QT prolongation, thyroid function abnormalities, pulmonary toxicity, and liver function tests, as well as medication reconciliation due to amiodarone's numerous drug interactions 1.

Additional Guidance

• Patients should be advised to use sun protection as amiodarone can cause photosensitivity reactions.
• The dosing regimen may need to be adjusted based on patient-specific factors, such as renal function and concomitant medications.
• The guidelines recommend a total dose over 24 hours not exceeding 2.2 g to minimize the risk of adverse effects 1.

From the FDA Drug Label

2 DOSAGE & ADMINISTRATION Amiodarone shows considerable interindividual variation in response. Although a starting dose adequate to suppress life-threatening arrhythmias is needed, close monitoring with adjustment of dose is essential The recommended starting dose of amiodarone is about 1000 mg over the first 24 hours of therapy, delivered by the following infusion regimen:

The rate of the maintenance infusion may be increased to achieve effective arrhythmia suppression Based on the experience from clinical studies of intravenous amiodarone, a maintenance infusion of up to 0. 5 mg/min can be continued for 2 to 3 weeks

The appropriate dosage of Amiodarone for atrial fibrillation (Afib) with rapid ventricular response (RVR) is a starting dose of about 1000 mg over the first 24 hours of therapy, followed by a maintenance infusion rate of up to 0.5 mg/min. The dose may be individualized and adjusted based on the patient's response to the medication 2.

• The initial infusion rate should not exceed 30 mg/min.
• The maintenance infusion rate may be increased to achieve effective arrhythmia suppression.
• The medication should be administered through a central venous catheter whenever possible, and an in-line filter should be used during administration.

From the Research

Dosage of Amiodarone for Atrial Fibrillation with Rapid Ventricular Response

• The appropriate dosage of Amiodarone for atrial fibrillation (Afib) with rapid ventricular response (RVR) can vary depending on the specific patient population and clinical setting.
• According to a study published in the European Heart Journal 3, a loading dose of i.v. amiodarone (repeated boluses of 3 mg/kg in 3 min, or 30 min-infusions of 5 to 7.5 mg/kg) followed by continuous infusion to reach a maximal total dosage of 1500 mg in 24 h was effective in converting Afib to sinus rhythm in 80.8% of patients.
• Another study published in the International Journal of Cardiology 4 reported that the dose of i.v. bolus given ranged from 3 to 7 mg/kg body weight and that of infusion from 900 to 3000 mg/day, with the highest 24-h conversion rates reported with the i.v. regimen of 125 mg/h until conversion or a maximum of 3 g.
• A study published in the Journal of Cardiovascular Pharmacology and Therapeutics 5 noted that the most immediate and most predictable response to intravenous amiodarone is reduction of the ventricular rate, which generally is noted after the first 300-400 mg, and that restoration of sinus rhythm may occur, but often takes 24 hours and a total dose of 1,000 mg or more.

Administration and Efficacy

• The administration of 7 mg/kg of intravenous amiodarone delivered in 30 min proved a safe and successful first choice of management in atrial fibrillation with a rapid ventricular response 3.
• Amiodarone had the highest rate of success if used initially (83%) and secondarily (85%) for rate and rhythm control in patients with new-onset Afib with RVR in the surgical intensive care unit 6.
• The efficacy of amiodarone in converting Afib to sinus rhythm has been reported to be 34-69% with bolus only regimens, and 55-95% with bolus followed by infusion regimens 4.

Comparison with Other Treatments

• A study published in Clinical and Experimental Pharmacology & Physiology 7 compared the efficacy of digoxin versus low-dose amiodarone for ventricular rate control in patients with chronic Afib, and found that both treatments had similar efficacy in controlling ventricular rate during ambulatory activity and exercise.
• Amiodarone is not superior to other antiarrhythmic drugs conventionally used for the pharmacological cardioversion of recent-onset Afib, but is relatively safe in patients with structural heart disease and in those with depressed left ventricle function 4.