What is the loading dose of digoxin (Digitalis) for atrial fibrillation (Afib)?

From the Guidelines

Digoxin loading for atrial fibrillation typically involves an initial loading dose of 0.25 mg IV each 2 h, up to 1.5 mg, as recommended by the ACC/AHA/ESC 2006 guidelines 1. The loading dose should be adjusted based on patient factors including age, weight, renal function, and concomitant medications. For elderly patients or those with impaired renal function, lower loading doses should be used. Serum digoxin levels should be monitored, aiming for a therapeutic range of 0.8-2.0 ng/mL, with levels drawn at least 6-8 hours after the last dose. Some key points to consider when using digoxin for atrial fibrillation include:

• The mechanism of action: Digoxin works by inhibiting the sodium-potassium ATPase pump, which increases intracellular calcium and enhances cardiac contractility while slowing conduction through the AV node.
• The therapeutic range: Serum digoxin levels should be monitored to avoid toxicity, with a therapeutic range of 0.8-2.0 ng/mL.
• Potential side effects: Signs of toxicity include nausea, vomiting, visual disturbances, and cardiac arrhythmias, which require immediate dose adjustment or discontinuation.
• Patient factors: The loading dose should be adjusted based on patient factors, including age, weight, renal function, and concomitant medications. It's also important to note that digoxin is no longer considered first-line therapy for rapid management of AF, except in patients with HF or LV dysfunction, or perhaps in patients who are so sedentary as to obviate the need for rate control during activity, as stated in the 2011 ACCF/AHA/HRS focused updates incorporated into the ACC/AHA/ESC 2006 guidelines 1. Additionally, the combination of digoxin and beta-blockers appears to be more effective than the combination of digoxin and diltiazem for rate control in atrial fibrillation, as mentioned in the ACC/AHA/ESC 2001 guidelines 1. Overall, the use of digoxin for atrial fibrillation should be individualized and based on the specific patient's needs and circumstances.

From the FDA Drug Label

Peak digoxin body stores larger than the 8 to 12 mcg/kg required for most patients with heart failure and normal sinus rhythm have been used for control of ventricular rate in patients with atrial fibrillation Doses of digoxin used for the treatment of chronic atrial fibrillation should be titrated to the minimum dose that achieves the desired ventricular rate control without causing undesirable side effects.

The loading dose for atrial fibrillation (afib) is not explicitly stated, but it is mentioned that peak digoxin body stores larger than 8 to 12 mcg/kg may be used.

• The usual amount of digoxin tablets that a 70 kg patient requires to achieve 8 to 12 mcg/kg peak body stores is 750 to 1250 mcg (0.75 to 1.25 mg) 2.
• A single initial dose of 500 to 750 mcg (0.5 to 0.75 mg) of digoxin tablets usually produces a detectable effect in 0.5 to 2 hours that becomes maximal in 2 to 6 hours 2.
• Additional doses of 125 to 375 mcg (0.125 to 0.375 mg) may be given cautiously at 6 to 8-hour intervals until clinical evidence of an adequate effect is noted 2 2.

From the Research

Digoxin Loading for Atrial Fibrillation

• Digoxin is used to control ventricular rate in atrial fibrillation (AF) and its use in patients with AF and heart failure (HF) has been studied extensively 3, 4, 5.
• A study published in 2015 found that digoxin use in patients with AF and HF is not associated with increased mortality, but it is associated with increased mortality in patients with AF without HF 3.
• Another study published in 2016 discussed the use of beta-blockers and digoxin for rate control in patients with AF and HF, and found that beta-blockers are almost always required to achieve rate control, while digoxin may be useful in certain situations, such as hypotension or contraindication to beta-blockers 4.
• A 2024 study investigated the use of digoxin loading doses for rate control of atrial arrhythmias in critically ill patients, and found that a median total loading dose of 750 mcg may be considered for acute rate control, targeting a serum digoxin concentration of less than 1.5 ng/mL 6.
• The safety and efficacy of digoxin in patients with AF have been debated, with some studies suggesting increased mortality associated with its use, while others have found it to be effective for rate control 7, 5.
• A 2009 study compared the effects of beta blockers and digoxin on mortality in patients with AF and HF, and found that treatment with beta blocker alone or with beta blocker plus digoxin was associated with a decreased mortality, while treatment with digoxin alone was not associated with a better survival 5.