Major
Clarithromycin × Digoxin
Macrolide antibiotic×Cardiac glycosides (digitalis)
Mechanism
Clarithromycin blocks intestinal P-glycoprotein and suppresses gut flora that partly inactivates digoxin. Digoxin plasma levels rise 1.7- to 2.5-fold.
Symptoms
Nausea, anorexia, visual disturbances (yellow-green halos around lights), arrhythmias ranging from premature beats to ventricular tachycardia. Older adults: confusion, dizziness. Symptoms appear within 1–2 weeks of co-administration.
Management
During clarithromycin therapy, reduce digoxin by 50%; check level at 5–7 days. Alternative antibiotics without P-glycoprotein block: azithromycin or doxycycline.
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.