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.
This article reports a case of considerable increase in the blood level of tacrolimus after the intake of pomelo in a renal transplant recipient.
Pomelo may increase the blood concentration of tacrolimus by inhibiting CYP 3A4, P-glycoprotein, or both.
Patients taking drugs such as tacrolimus or cyclosporine, which have their kinetics affected by grapefruit juice, should avoid pomelo and other grapefruit-related citrus fruits.
1 Graduate School of Pharmaceutical Sciences, Kyushu University, Japan.
2 Address correspondence to: Yasufumi Sawada, Ph.D., Professor, Department of Medico-Pharmaceutical Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, 3–1-1 Maidashi, Higashi-ku, Fukuoka 812–8582, Japan. E-mail: firstname.lastname@example.org.
3 Department of Pharmacy, National Nagasaki Medical Center, 2–1001–1 Kubara, Omura, Nagasaki 856–8562, Japan.
Received 23 October 2002.
Accepted 3 December 2002.