title: In vitro metabolism and inhibitory effects of pranlukast in human liver microsomes.
abstract: We investigated the metabolism of pranlukast, a selective leukotriene agonist, and the potential for drug-drug interactions. Although cytochrome P450 (CYP) 3A4 appeared to be the major cytochrome P450 isoform involved in the metabolism of pranlukast, the results suggested that pranlukast metabolism was inhibited less than 50% by ketoconazole, a reversible CYP3A4 inhibitor, or by anti-CYP3A4 antibodies. Irreversible macrolide CYP3A4 inhibitors, clarithromycin, erythromycin and roxithromycin, exhibited little effect on pranlukast metabolism. On the other hand, pranlukast reversibly inhibited CYP2C8 and/or 2C9, and CYP3A4, with K(i) values of 3.9 and 4.1 micromol/l, respectively. The [I](in,max,u)/K(i) ratios were 0.004 and 0.003, respectively. The K(i) values were about 300-fold greater than the [I](in,max,u), therefore it is suggested that, at clinical doses, pranlukast will not affect the pharmacokinetics of concomitantly administered drugs that are primarily metabolized by CYP2C8 and/or 2C9 or CYP3A4.
authors.affiliation: Pharmacokinetic Research Laboratories, Ono Pharmaceutical Co., Ltd, Japan. yoneda@ono.co.jp
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yoneda
authors.forename: Ichiro
authors.initials: I
authors.lastname: Matsumoto
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Sutoh
authors.forename: Ryunosuke
authors.initials: R
authors.lastname: Higashi
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Nunoya
authors.forename: Susumu
authors.initials: S
authors.lastname: Nakade
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Miyata
authors.forename: Mikio
authors.initials: M
authors.lastname: Ogawa