What are the loading and maintenance doses of Amiodarone (antiarrhythmic medication) for Atrial Fibrillation (Afib)?

From the Guidelines

Amiodarone for atrial fibrillation should be initiated with a loading dose of 400-600 mg orally in divided doses for 2-4 weeks, followed by a maintenance dose of 100-200 mg orally once daily. This regimen is based on the most recent and highest quality study available, which is the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1. The loading dose can be up to 1200 mg orally per day in an inpatient monitoring setting, but the maintenance dose should be minimized to reduce long-term adverse effects.

Some key points to consider when using amiodarone for atrial fibrillation include:

• Monitoring for potential adverse effects such as bradycardia, QT prolongation, torsades de pointes, gastrointestinal upset, constipation, hypothyroidism, hyperthyroidism, pulmonary fibrosis, hepatic toxicity, corneal deposits, optic neuritis, peripheral neuropathy, and photosensitivity 1
• Precautions and interactions, including sinus or AV conduction disease, inflammatory lung disease, hepatic dysfunction, hypothyroidism, hyperthyroidism, peripheral neuropathy, and drugs with SA and/or AV nodal-blocking properties 1
• The use of low-dose amiodarone (200 mg daily or less) may be effective and associated with fewer side effects, as suggested by previous studies 1
• Amiodarone is more effective than other antiarrhythmic agents in maintaining sinus rhythm, but it is associated with a higher incidence of potentially severe extracardiac toxic effects, making it a second-line or last-resort agent in many cases 1

It is essential to regularly monitor thyroid, liver, and pulmonary function during long-term therapy with amiodarone due to potential toxicities. Patients should also be advised about photosensitivity and the need to use sunscreen. The drug's very long half-life (40-55 days) due to extensive tissue distribution and accumulation, particularly in adipose tissue, liver, and lungs, should be taken into consideration when initiating and adjusting the dose.

From the FDA Drug Label

DOSAGE & ADMINISTRATION Amiodarone shows considerable interindividual variation in response. Thus, although a starting dose adequate to suppress life-threatening arrhythmias is needed, close monitoring with adjustment of dose as needed is essential The recommended starting dose of amiodarone HCl injection is about 1000 mg over the first 24 hours of therapy After the first 24 hours, the maintenance infusion rate of 0. 5 mg/min (720 mg/24 hours) should be continued The rate of the maintenance infusion may be increased to achieve effective arrhythmia suppression.

The loading dose for amiodarone is about 1000 mg over the first 24 hours of therapy. The maintenance dose is 0.5 mg/min, which is equivalent to 720 mg/24 hours. Key points to consider:

• Close monitoring with adjustment of dose as needed is essential due to interindividual variation in response.
• The maintenance infusion rate may be increased to achieve effective arrhythmia suppression 2.

From the Research

Amiodarone Loading and Maintenance for Afib

• Amiodarone is recognized as the most effective therapy for maintaining sinus rhythm post cardioversion in patients with atrial fibrillation (Afib) 3, 4, 5.
• The use of low-dose amiodarone as a first-line agent in patients with Afib has been suggested, particularly in those with congestive heart failure or coronary artery disease 6.
• Amiodarone has been shown to be effective in converting recent onset Afib to sinus rhythm, with a single oral loading dose resulting in conversion rates of up to 72.6% at 3 months 4, 7.
• The pharmacokinetics of amiodarone make it a suitable option for episodic treatment, with a rapid distribution to myocardial tissue and low interindividual variability of absorption kinetics 7.
• However, amiodarone can cause serious noncardiac side effects, such as pulmonary fibrosis, thyroid dysfunction, hepatitis, and neurotoxicity, and may interact with other medications, such as digoxin and coumadin 3, 5.
• The effective dose of amiodarone for maintaining sinus rhythm in patients with Afib is typically in the range of 200-400 mg/day 4, 5.
• The use of amiodarone in patients with Afib and congestive heart failure has been shown to improve left ventricular function and decrease B-type natriuretic peptide (BNP) levels 5.
• Amiodarone has been compared to other antiarrhythmic agents, such as flecainide and quinidine, and has been shown to be more effective in maintaining sinus rhythm in patients with Afib 4, 7.