Pomelo-induced increase in the blood level of tacrolimus in a renal transplant patient.

Background: Tacrolimus, an immunosuppressive agent, is widely used in patients after transplantation to prevent allograft rejection. Because tacrolimus has a narrow therapeutic range, it is essential to carefully control the blood level. It has been demonstrated that tacrolimus is metabolized mainly by cytochrome P-450 (CYP) 3A4, and that tacrolimus is a substrate of P-glycoprotein.