What is the recommended loading dose of amiodarone (antiarrhythmic medication)?

From the Guidelines

The recommended loading dose of amiodarone is typically 150 mg given 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. This loading approach is necessary because amiodarone has an extremely long half-life (40-55 days) and large volume of distribution, requiring initial higher doses to achieve therapeutic levels quickly 1. The medication accumulates in adipose tissue and highly perfused organs like the liver, lungs, and spleen. Patients should be monitored for potential side effects during loading, including hypotension with IV administration, QT prolongation, bradycardia, and heart block. Dosing may need adjustment based on patient weight, age, hepatic function, and concomitant medications. Some key points to consider when administering amiodarone include:

• The initial dose is usually followed by a maintenance dose of 100-200 mg daily 1
• Amiodarone can be used for both ventricular and supraventricular arrhythmias 1
• The medication has a number of potential side effects, including cardiac effects such as bradycardia and hypotension, as well as non-cardiac effects such as gastrointestinal upset and photosensitivity 1
• Amiodarone has a number of interactions with other medications, including warfarin and digoxin, and should be used with caution in patients taking these medications 1. It's also important to note that amiodarone is not typically used as a first-line treatment for arrhythmias, but rather for patients who have not responded to other treatments or who have life-threatening arrhythmias 1.

From the FDA Drug Label

The recommended starting dose of amiodarone is about 1000 mg over the first 24 hours of therapy, delivered by the following infusion regimen: The recommended loading dose of amiodarone is about 1000 mg over the first 24 hours of therapy.

• The dose may be individualized for each patient.
• Do not exceed an initial infusion rate of 30 mg/min. 2

From the Research

Loading Dose of Amiodarone

The recommended loading dose of amiodarone varies depending on the specific clinical scenario and the route of administration.

• For oral administration, a loading dose of 50 mg/kg per day for 3 days, then 30 mg/kg per day for 2 days, followed by maintenance therapy of 300 to 400 mg twice daily has been used in some studies 3.
• For intravenous administration, a bolus dose of 5 mg/kg over 30 minutes followed by 20 to 30 mg/kg/day as a constant infusion for 5 days has been used 4.
• A dose-ranging study of intravenous amiodarone found that a dose of 1000 mg during the first 24 hours was effective in reducing the arrhythmia event rate and increasing the time to first event 5.
• For patients with recent-onset atrial tachyarrhythmia, a single oral loading dose of 25-30 mg/kg body weight has been shown to be effective and well-tolerated 6.
• For pharmacological cardioversion of recent-onset atrial fibrillation, intravenous amiodarone has been used as a bolus only or as a bolus followed by a continuous infusion, with doses ranging from 3 to 7 mg/kg body weight for the bolus and 900 to 3000 mg/day for the infusion 7.

Key Considerations

• The choice of loading dose and route of administration should be individualized based on the patient's specific clinical scenario and medical history.
• Amiodarone can cause serious adverse events, including hypotension, bradycardia, and sinus arrest, so close monitoring is necessary during the loading period 4, 5.
• The efficacy and safety of amiodarone for pharmacological cardioversion of recent-onset atrial fibrillation have been established, but it is not superior to other antiarrhythmic drugs conventionally used for this purpose 7.