Drug Interactions With Cyclosporine-Rifampicin-Clarithromycin in a Kidney Transplant Recipient With Mycobacterium Malmoense

Abstract

A 38-year-old kidney transplant recipient was treated with antituberculous drugs due to mycobacterial joint infection due to Mycobacterium malmoense. Three days of starting combined therapy, cyclosporine blood concentration (CBC) decreased a 63% and was necessary to increase the cyclosporine dose. Clarithromycin was also added and the CBC and kidney function remained stable until 11 months later. Pirazinamide and isoniazide were withdrawn four months before without any analytical changes but when rifampicin and ethambutol were withdrawn, CBC showed an increase of 377% and creatinine level was worsened. It was necessary to reduce the cyclosporine dose and renal function improved within 6 weeks. When clarithromycin was discontinued, the CBC decreased a 69% which motivated gradually increasing the dose. CBC is liable to change in patients treated with drugs metabolized by cytochrome p450 system, and the effect and magnitude of a multiple interaction is unpredictable. Close monitoring is necessary to adjust the dosage.