Critical
Ciclosporin × Dronedarone
Immunosuppressants. Calcineurin inhibitors×Class III antiarrhythmic
Mechanism
Cyclosporine is a strong CYP3A4 and P-glycoprotein inhibitor. Dronedarone levels rise several-fold, plus cyclosporine itself is proarrhythmic. FDA Multaq Section 4.3 specifically lists cyclosporine.
Symptoms
QT prolongation on ECG. Clinically: dizziness, syncope, palpitations. Severe cases progress to polymorphic ventricular tachycardia (torsades de pointes) with risk of ventricular fibrillation and sudden cardiac death. Risk rises with hypokalaemia and hypomagnesaemia.
Management
The combination is not prescribed. For post-transplant atrial fibrillation, use amiodarone or rhythm control via catheter ablation. Alternative immunosuppression: tacrolimus, with attention to its own QT risk.