What are the guidelines for transitioning from intravenous (IV) to oral (PO) amiodarone?

From the Guidelines

When transitioning from intravenous (IV) to oral (PO) amiodarone, patients who received IV amiodarone for less than one week should take 800 to 1,600 mg oral amiodarone per day, while those who received IV amiodarone for one to three weeks should take 600 to 800 mg oral amiodarone per day, and patients who received IV amiodarone for more than three weeks should take 400 mg oral amiodarone per day. This recommendation is based on the most recent guidelines for amiodarone use and monitoring 1.

Key Considerations

• The transition from IV to oral amiodarone should occur when the patient is hemodynamically stable and the arrhythmia is controlled.
• The oral bioavailability of amiodarone is approximately 50%, which explains the higher oral dosing requirements compared to IV administration.
• Patients should be monitored for QT prolongation, thyroid dysfunction, pulmonary toxicity, and liver function abnormalities during this transition.
• Food enhances the absorption of oral amiodarone, so it should be taken with meals.

Dosage Guidelines

• For life-threatening arrhythmia, the IV dosage is typically converted to oral dosing when possible, with a dosage of 800 to 1,600 mg per day in divided doses until a total of 10 g has been given, then 200 to 400 mg per day 1.
• For ventricular arrhythmia, the oral dosage is 800 to 1,600 mg per day in divided doses until a total of 10 g has been given, then 200 to 400 mg per day 1.
• For atrial fibrillation, the oral dosage is 600 to 800 mg per day in divided doses until a total of 10 g has been given, then 200 mg per day 1.

From the FDA Drug Label

The optimal dose for changing from intravenous to oral administration of amiodarone will depend on the dose of amiodarone HCl injection already administered, as well as the bioavailability of oral amiodarone When changing to oral amiodarone therapy, clinical monitoring is recommended, particularly for elderly patients. The following table provides suggested doses of oral amiodarone to be initiated after varying durations of amiodarone HCl injection administration.

The guidelines for transitioning from intravenous (IV) to oral (PO) amiodarone are as follows:

• The optimal dose for changing from IV to oral administration of amiodarone depends on the dose of amiodarone HCl injection already administered and the bioavailability of oral amiodarone.
• Clinical monitoring is recommended when switching to oral amiodarone therapy, especially for elderly patients.
• A table is provided to suggest doses of oral amiodarone to be initiated after varying durations of amiodarone HCl injection administration, based on a comparable total body amount of amiodarone delivered by the IV and oral routes, assuming 50% bioavailability of oral amiodarone 2.

From the Research

Transitioning from IV to Oral Amiodarone

The guidelines for transitioning from intravenous (IV) to oral (PO) amiodarone are not well-established, but several studies provide insight into the process.

• A study from 1985 3 compared IV and oral loading with oral loading alone and found that the combination of IV and oral loading shortened the time to optimal ventricular arrhythmia control and lowered the cumulative dose required.
• Another study from 1992 4 examined the effects of high-dose oral amiodarone loading and found that it was well-tolerated in most patients and resulted in significant increases in ventricular tachycardia cycle length and right ventricular effective refractory period.
• A 2019 study 5 assessed the impact of IV and PO amiodarone overlap on short-term tachyarrhythmia recurrence and adverse hemodynamic outcomes in critically ill patients, finding that providing IV and PO overlap for a median of 4 hours did not decrease the rate of early tachyarrhythmia recurrence.
• Practical aspects of amiodarone use, including oral loading doses and potential side effects, are discussed in a 1991 study 6.
• A 2013 study 7 explored the use of intrapericardial delivery of amiodarone to rapidly achieve therapeutic levels in the atrium, finding that this method was safe and effective in achieving high concentrations of amiodarone in myocardial tissues without appreciable systemic presence.

Key Considerations

When transitioning from IV to oral amiodarone, the following factors should be considered:

• The use of IV and oral loading to rapidly achieve therapeutic levels 3, 4
• The potential for side effects, such as hypotension and bradycardia 5
• The importance of monitoring electrolyte levels and cardiac function 6
• The potential benefits of alternative dosing strategies, such as intrapericardial delivery 7