Clarithromycin × Ciclosporin

Cyclosporine is cleared through CYP3A4, and clarithromycin inhibits this enzyme. Clarithromycin roughly doubles cyclosporine exposure (cyclosporine SmPC). Excess cyclosporine damages the kidneys and raises blood pressure (cyclosporine SmPC).

Rising creatinine and urea, high blood pressure, tremor, headache, high blood potassium.

During the clarithromycin course, adjust the cyclosporine dose according to its blood concentration. The US Food and Drug Administration (FDA) lists clarithromycin among drugs that increase cyclosporine concentrations and states that dose adjustment to the desired concentration is essential when a drug significantly alters cyclosporine levels (cyclosporine FDA label). In transplant recipients, measure cyclosporine levels frequently, especially when clarithromycin is started and stopped, and adjust the dose as needed (cyclosporine SmPC). In patients without a transplant, check kidney function more often and watch for cyclosporine adverse effects (cyclosporine SmPC).