From the Guidelines
The recommended dose of amiodarone for treating atrial fibrillation typically begins with a loading dose of 400-600 mg orally per day, divided into 1-3 doses, for 2-4 weeks, as stated in the 2016 guidelines 1. This is followed by a maintenance dose of 100-200 mg orally once daily. For acute situations requiring rapid control, an intravenous loading dose of 150 mg over 10 minutes can be administered, followed by 1 mg/min for 6 hours, then 0.5 mg/min for 18 hours. After IV administration, patients should transition to oral therapy. Amiodarone works by blocking potassium channels, prolonging the cardiac action potential and refractory period, which helps restore and maintain normal sinus rhythm. Some key points to consider when using amiodarone include:
- Monitoring for side effects including thyroid dysfunction, pulmonary toxicity, liver abnormalities, and QT prolongation 1
- Regular follow-up with ECGs, liver function tests, thyroid function tests, and chest X-rays is necessary 1
- Dose adjustments may be needed based on patient response, age, and comorbidities 1
- Amiodarone can be useful to control the heart rate in patients with atrial fibrillation when other measures are unsuccessful or contraindicated 1 It's also important to note that amiodarone is associated with a relatively high incidence of potentially severe extracardiac toxic effects, making it a second-line or last-resort agent in many cases 1. However, the use of low-dose amiodarone (200 mg daily or less) may be effective and associated with fewer side effects 1. Overall, the decision to use amiodarone and the dosage used should be individualized based on the patient's specific condition and medical history.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION Initiate treatment with a loading doses of 800 to 1600 mg/day until initial therapeutic response occurs (usually 1 to 3 weeks). Once adequate arrhythmia control is achieved, or if side effects become prominent, reduce amiodarone hydrochloride tablets dose to 600 to 800 mg/day for one month and then to the maintenance dose, usually 400 mg/day.
The recommended dose of Amiodarone for treating atrial fibrillation is not explicitly stated in the provided drug labels, as the labels primarily discuss the treatment of life-threatening recurrent ventricular fibrillation and life-threatening recurrent hemodynamically unstable tachycardia.
- Loading dose: 800 to 1600 mg/day for 1 to 3 weeks
- Reduction dose: 600 to 800 mg/day for one month
- Maintenance dose: usually 400 mg/day However, it's crucial to note that the provided drug labels do not directly address the treatment of atrial fibrillation with Amiodarone. 2, 2, 2
From the Research
Amiodarone Dose for Atrial Fibrillation
The recommended dose of Amiodarone for treating atrial fibrillation varies depending on the study and the specific treatment regimen.
- The dose of intravenous (i.v.) bolus given ranged from 3 to 7 mg/kg body weight and that of infusion from 900 to 3000 mg/day 3.
- A study found that only the higher dose (>1500 mg/day) amiodarone is superior to placebo in converting recent-onset atrial fibrillation to sinus rhythm 3.
- The highest 24-h conversion rates have been reported with the i.v. regimen of 125 mg/h until conversion or a maximum of 3 g and the oral regimen of 25-30 mg/kg body weight administered as a single loading-dose (>90% and >85%, respectively) 3.
- Another study used a dose of 300 mg IV for 1 h, and then 20 mg/kg for 24 h, followed by 600 mg/d orally, divided into three doses, for 1 week, and thereafter 400 mg/d for 3 weeks 4.
- Low-dose amiodarone (less than 300 mg/d) has been reported to be well tolerated and effective in maintaining sinus rhythm in 53% to 79% of patients during a mean follow-up of 27 months 5.
Factors Affecting Conversion to Sinus Rhythm
Several factors can affect the conversion to sinus rhythm, including: