Pharmacokinetic interaction between voriconazole and ciclosporin A following allogeneic bone marrow transplantation

Voriconazole is a novel antifungal triazole that undergoes extensive oxidative metabolization involving several CYP450 isoenzymes. We report the case of a 14-year-old patient who received voriconazole concomitant with ciclosporin A as secondary antifungal prophylaxis after bone marrow transplantation. Temporary discontinuation of voriconazole due to worsening liver function tests (LFTs) resulted in a sudden drop of ciclosporin A trough levels in blood. Ciclosporin A trough levels returned to baseline following normalization of LFTs and re-institution of voriconazole. This report emphasizes the need for careful monitoring and dose adjustments of ciclosporin A in patients receiving concomitant voriconazole, and in whom voriconazole is discontinued in order to prevent subtherapeutic ciclosporin A levels with the potential consequence of graft-versus-host disease.