Elevation of blood ciclosporin levels by voriconazole leading to leukoencephalopathy

We report that one 18-year-old female patient with no epilepsia history developed severe epileptiform seizures while she was receiving “ciclosporin A (CsA)-mycophenolate-methylprednisolone” antirejection therapy after combining one week's voriconazole administration following allogeneic hematopoietic stem cell transplantation (allo-HSCT) for myelodysplastic syndromes (MDS). Her blood concentration of CsA was 378 ng/ml (elevated ↑64%, contrasted with the level before the addition of voriconazole) on the second day of admission, and the MRI of head showed leukoencephalopathy in bilateral occipital and left frontal lobe on the 4(th) day of admission. The most likely mechanism is that because of voriconazole's enzyme inhibition and CsA as the substrate of hepatic enzymes, voriconazole elevated the blood concentration of CsA and enhanced its toxicity. This case highlights the importance of clinical pharmacists joining the medical team and optimizing the patients’ treatment protocols by performing a systematic literature research, accumulating the knowledge of the potential drug interaction and examining prescriptions.