title: In vitro and in vivo CYP3A64 induction and inhibition studies in rhesus monkeys: a preclinical approach for CYP3A-mediated drug interaction studies.
abstract: In this study, induction and inhibition of rhesus monkey CYP3A64 versus human CYP3A4 were characterized in vitro, and the corresponding pharmacokinetic consequences were evaluated in rhesus monkeys. In monkey hepatocytes, rifampin markedly induced CYP3A64 mRNA (EC50 = 0.5 microM; Emax = 6-fold) and midazolam (MDZ) 1'-hydroxylase activity (EC50 = 0.2 microM; Emax = 2-fold). Compound A (N-[2(R)-hydroxy-1(S)-indanyl-5-[2(S)-(1,1-dimethylethylaminocarbonyl)-4-[(furo[2,3-b]pyridin-5-yl)-methyl]piperazin-1-yl]-4(S)-hydroxy-2(R)-phenylmethylpentanamide), a known potent and mechanism-based inhibitor of CYP3A4, strongly inhibited the formation of 1'-hydroxy MDZ by recombinant CYP3A64 in a concentration- and time-dependent manner (KI = 0.25 microM; k(inact) = 0.4 min(-1)). Similar corresponding results also were obtained with human CYP3A4 in the presence of rifampin or compound A. In rhesus monkeys, MDZ exhibited a relatively high metabolic clearance (primarily via 1'-hydroxylation followed by glucuronidation) and a low hepatic availability (Fh = 16%). Consistent with the induction of hepatic metabolism of a high-clearance compound, pretreatment with rifampin (18 mg/kg p.o. for 5 days) did not significantly affect the i.v. kinetics of MDZ, but caused a pronounced reduction (approximately 10-fold) in the systemic exposure to MDZ and, consequently, its Fh following intrahepatic portal vein administration (i.pv.) of MDZ. A comparable extent of the pharmacokinetic interaction also was obtained after a 1.8 mg/kg rifampin dose. Also consistent with the in vitro CYP3A64 inhibition finding, compound A (6 mg/kg i.v.) markedly increased (10-fold) the i.pv. administered MDZ exposure. At the doses studied, plasma concentrations of rifampin or compound A reached or exceeded their respective in vitro EC50 or KI values. These findings suggest the potential applicability of the in vitro-in vivo relationship approach in rhesus monkeys for studying CYP3A-mediated interactions in humans.
authors.affiliation: Department of Drug Metabolism, WP75-100, Merck Research Laboratories, West Point, PA 19486, USA. thomayant_prueksaritanont@merck.com
authors.forename: Thomayant
authors.initials: T
authors.lastname: Prueksaritanont
authors.forename: Yuhsin
authors.initials: Y
authors.lastname: Kuo
authors.forename: Cuyue
authors.initials: C
authors.lastname: Tang
authors.forename: Chunze
authors.initials: C
authors.lastname: Li
authors.forename: Yue
authors.initials: Y
authors.lastname: Qiu
authors.forename: Bing
authors.initials: B
authors.lastname: Lu
authors.forename: Kristie
authors.initials: K
authors.lastname: Strong-Basalyga
authors.forename: Karen
authors.initials: K
authors.lastname: Richards
authors.forename: Brian
authors.initials: B
authors.lastname: Carr
authors.forename: Jiunn H
authors.initials: JH
authors.lastname: Lin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D002478:Cells, Cultured; D051544:Cytochrome P-450 CYP3A / Q000096:biosynthesis* / Q000235:genetics; D065692:Cytochrome P-450 CYP3A Inhibitors; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000235:genetics; D004353:Drug Evaluation, Preclinical / Q000379:methods; D004347:Drug Interactions; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000493:pharmacokinetics / Q000494:pharmacology; D004987:Ethers / Q000493:pharmacokinetics / Q000494:pharmacology; D005260:Female; D022781:Hepatocytes / Q000187:drug effects / Q000201:enzymology*; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000493:pharmacokinetics / Q000494:pharmacology; D006900:Hydroxylation; D007262:Infusions, Intravenous; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D008253:Macaca mulatta; D008297:Male; D008874:Midazolam / Q000008:administration & dosage / Q000493:pharmacokinetics; D008875:Middle Aged; D023421:Models, Animal; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D012293:Rifampin / Q000493:pharmacokinetics / Q000494:pharmacology
chemical_list: D065692:Cytochrome P-450 CYP3A Inhibitors; D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D004987:Ethers; D006845:Hydrocarbons, Fluorinated; D007527:Isoenzymes; D012333:RNA, Messenger; D011994:Recombinant Proteins; C078742:fluoromethyl 2,2-difluoro-1-(trifluoromethyl)vinyl ether; D003577:Cytochrome P-450 Enzyme System; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D008874:Midazolam; D012293:Rifampin