Critical
Amiodarone × Digoxin
Class III antiarrhythmics (Vaughan Williams)×Cardiac glycosides (digitalis)
Mechanism
Amiodarone blocks P-glycoprotein in the intestine and renal tubules – the main dabigatran-style clearance route of digoxin. Digoxin plasma levels rise 1.7- to 2.5-fold. The narrow therapeutic window of digoxin turns any rise into a risk of acute toxicity.
Symptoms
Nausea, anorexia, visual disturbances (yellow-green halos around lights), arrhythmias ranging from premature beats to ventricular tachycardia. In older adults: confusion, dizziness. Symptoms appear 1–2 weeks after starting amiodarone.
Management
When amiodarone is started, halve the digoxin dose immediately. Measure digoxin level after 1 week (target 0.5–0.9 ng/mL in heart failure). Check potassium and magnesium monthly: hypokalaemia worsens digoxin toxicity.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Sources
- Lexicomp: Lexicomp Drug Interactions (2024)– Wolters Kluwer Clinical Drug Information, Inc. Lexi-Interact Online, 2024
- Pharmaceutical Press: Stockley's Drug Interactions, 12th edition (2024)– Preston CL (ed.). Stockley's Drug Interactions. 12th ed. London: Pharmaceutical Press; 2024
- ESC: 2024 ESC Guidelines for the management of atrial fibrillation developed in collaboration with the EACTS (2024)– Eur Heart J 2024;45(36):3314–3414