title: Inhibitory effects of pomelo on the metabolism of tacrolimus and the activities of CYP3A4 and P-glycoprotein.
abstract: We recently reported a case of increase in the blood level of tacrolimus following intake of pomelo in a renal transplant recipient. To clarify the mechanism of this increase in the blood level of tacrolimus, we investigated the effect of pomelo juice extract on the activities of CYP3A4 and P-glycoprotein, in comparison with that of extract of grapefruit juice (GFJ). The 10% ethyl acetate extracts of the juice of three pomelos of different origins (Banpeiyu, pomelo I; Hirado Buntan, pomelo II; and Tosa Buntan, pomelo III) and GFJ significantly inhibited 6beta-hydroxylation of testosterone in human liver microsomes by 76.4, 67.2, 37.5, and 83.9%, respectively. The extract of pomelo I was as potent as that of GFJ. The metabolism of tacrolimus itself was also inhibited by the extract of pomelo I, as well as that of GFJ. Furthermore, the inhibition of both 6beta-hydroxylation of testosterone and metabolism of tacrolimus by pomelo I and GFJ was preincubation time-dependent. On the other hand, the extract of pomelo I had little effect on the transcellular transport of tacrolimus or [(3)H]digoxin across a monolayer of LLC-GA5-COL150 cells (a porcine kidney epithelial cell line, LLC-PK1, transfected with human MDR1 cDNA and overexpressing human P-glycoprotein). In conclusion, pomelo constituents inhibit the activity of CYP3A4 and may thereby produce an increase in the blood level of tacrolimus.
authors.affiliation: Department of Medico-Pharmaceutical Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Kanoko
authors.initials: K
authors.lastname: Egashira
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Ohtani
authors.forename: Suwako
authors.initials: S
authors.lastname: Itoh
authors.forename: Noriko
authors.initials: N
authors.lastname: Koyabu
authors.forename: Masayuki
authors.initials: M
authors.lastname: Tsujimoto
authors.forename: Hideyasu
authors.initials: H
authors.lastname: Murakami
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Sawada
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002957:Citrus; D051544:Cytochrome P-450 CYP3A; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D006801:Humans; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D016559:Tacrolimus / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D065607:Cytochrome P-450 Enzyme Inhibitors; D010936:Plant Extracts; D003577:Cytochrome P-450 Enzyme System; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D016559:Tacrolimus