Major
Clarithromycin × Digoxin
Macrolide antibiotic×Cardiac glycosides (digitalis)
Mechanism
Clarithromycin inhibits intestinal and renal P-glycoprotein and suppresses gut flora that inactivates part of the digoxin dose. Digoxin plasma concentration rises 2–4 fold. Effect is stronger in the elderly and chronic kidney disease.
Symptoms
Within 3–7 days: nausea, vomiting, yellow vision halos, bradycardia, ventricular arrhythmias up to ventricular fibrillation.
Management
Reduce digoxin by 30–50% for the clarithromycin course and check level 3 days after start. Alternative: azithromycin, which lacks significant P-gp inhibition.
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.