Digoxin Dosing During Amiodarone Infusion

Mechanism of Interaction

• Amiodarone inhibits P-glycoprotein, which reduces digoxin clearance and increases serum digoxin concentrations, according to the American College of Cardiology 3, 4
• This interaction causes digoxin levels to predictably increase after coadministration with amiodarone, as reported by the American Academy of Family Physicians 4

Specific Dosing Recommendations

• For IV digoxin loading during amiodarone infusion, the American College of Cardiology recommends reducing the standard loading dose by 30-50% to approximately 0.125-0.35 mg IV bolus 1, 2, 3
• For maintenance dosing, the American College of Cardiology suggests reducing the standard maintenance dose by 30-50% from the calculated dose, based on patient's age, weight, and renal function 3, 4, 5, 6

Monitoring Requirements

• The American College of Cardiology recommends checking digoxin levels more frequently when initiating or adjusting amiodarone therapy, with a target trough serum digoxin level of 0.5-1.0 ng/mL 4, 5
• Monitoring for signs of digoxin toxicity is crucial, including gastrointestinal symptoms, neurological symptoms, and cardiac arrhythmias, as advised by the American College of Cardiology 1, 3, 7

Precautions

• The American College of Cardiology advises using digoxin with extreme caution in patients with renal dysfunction, pre-existing AV block or SA node dysfunction, and Wolff-Parkinson-White syndrome with atrial fibrillation/flutter 1, 2, 3
• The American Academy of Family Physicians recommends avoiding this combination in patients with second or third-degree heart block without a pacemaker 8