What is the bolus dosing for Amiodarone (Amio) in atrial fibrillation (afib)?

From the Guidelines

For atrial fibrillation, the recommended amiodarone bolus dosing is 150 mg administered intravenously 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, as supported by the most recent guidelines 1.

Key Considerations

• The maximum daily dose should not exceed 2.2 grams.
• Amiodarone works by blocking potassium channels, prolonging repolarization and the refractory period, which helps restore normal sinus rhythm.
• It's essential to monitor for hypotension during administration, especially with the initial bolus.
• ECG monitoring is crucial throughout treatment to observe for QT prolongation.
• Liver and thyroid function tests should be checked at baseline and periodically during treatment.
• Amiodarone has a very long half-life (approximately 58 days), so effects may persist for weeks after discontinuation.

Administration and Monitoring

• The bolus dose can be repeated if necessary, and the infusion rate can be adjusted based on the patient's response.
• For patients with severe heart failure or hypotension, consider reducing the initial bolus dose or slowing the infusion rate.
• The treatment should be individualized based on the patient's condition and response to the medication.

Evidence-Based Recommendation

The recommended dosing is based on the most recent guidelines from the American Heart Association 1, which provide evidence-based recommendations for the management of atrial fibrillation.

Important Notes

• Amiodarone can be useful to control the heart rate in patients with atrial fibrillation when other measures are unsuccessful or contraindicated 1.
• The medication should be used with caution in patients with certain conditions, such as heart failure or QT prolongation.

From the FDA Drug Label

The first 24-hour dose may be individualized for each patient; however, in controlled clinical trials, mean daily doses above 2100 mg were associated with an increased risk of hypotension. In the event of breakthrough episodes of VF or hemodynamically unstable VT, use 150 mg supplemental infusions of amiodarone (mixed in 100 mL of D5W and infused over 10 minutes to minimize the potential for hypotension)

The recommended bolus dosing for amiodarone in the treatment of afib is not explicitly stated, but a supplemental infusion of 150 mg can be used in the event of breakthrough episodes of VF or hemodynamically unstable VT, infused over 10 minutes 2.

From the Research

Amio Afib Bolus Dosing

• The dose of intravenous (i.v.) bolus amiodarone for pharmacological cardioversion of recent-onset atrial fibrillation ranged from 3 to 7 mg/kg body weight 3.
• The efficacy reported with bolus only regimens was 34-69%, and 55-95% with bolus followed by infusion regimens 3.
• Predictors of successful conversion to sinus rhythm include shorter duration of atrial fibrillation, smaller left atrial size, and higher amiodarone dose 3.
• Amiodarone is not superior to other antiarrhythmic drugs conventionally used for the pharmacological cardioversion of recent-onset atrial fibrillation, but is relatively safe in patients with structural heart disease and in those with depressed left ventricle function 3.
• The latest European Society of Cardiology AF guidelines state that amiodarone is recommended for long-term rhythm control in all AF patients, but other antiarrhythmic drugs should be considered first whenever possible, due to its extracardiac toxicity 4.
• Amiodarone has a complex pharmacokinetic profile, characterized by a large volume of distribution and a long half-life, which can range from several weeks to months, resulting in prolonged effects even after discontinuation 5.

Administration and Monitoring

• Amiodarone can be administered both intravenously and orally for the pharmacological cardioversion of recent-onset atrial fibrillation 3.
• Intravenous amiodarone has been used as a bolus only or as a bolus followed by a continuous i.v. infusion until conversion or up to 24 h 3.
• Routine monitoring is recommended for side effects such as thyroid abnormalities, pulmonary fibrosis, and transaminitis 6.
• Amiodarone interacts with several medications, such as warfarin, simvastatin, and atorvastatin, and many HIV antiretroviral medications, which must be managed to prevent adverse effects 6, 5.