Moderate
Ciclosporin × Digoxin
Immunosuppressants. Calcineurin inhibitors×Cardiac glycosides (digitalis)
Mechanism
Ciclosporin inhibits P-glycoprotein in gut and renal tubules, reducing digoxin clearance. Digoxin AUC rises by 50–100%; toxicity risk is substantial.
Symptoms
Nausea, vomiting, loss of appetite, confusion, yellow-green halos around lights, arrhythmia (bigeminy, AV block). Symptoms appear earlier in older patients and chronic kidney disease.
Management
On ciclosporin start, reduce digoxin dose by 25–50% and check levels at 5–7 days. Target: 0.5–0.8 ng/mL. In parallel, monitor potassium and creatinine (ciclosporin is nephrotoxic and raises hyperkalaemia risk).