title: Effects of P-glycoprotein and Mrp2 inhibitors on the hepatobiliary disposition of Rhodamine 123 and its glucuronidated metabolite in isolated perfused rat livers.
abstract: The hepatobiliary disposition of rhodamine 123 (RH-123) and its glucuronidated (RH-Glu) and deacylated (RH-110) metabolites were studied in an isolated perfused rat liver (IPRL) model in the presence and absence of P-glycoprotein (P-gp) and Mrp2 inhibitors. A single dose (180 microg) of RH-123 was added to a recirculating perfusate in the absence (Control) or presence of cyclosporine A (CyA) or dibromosulfophthalein (DBSP) in the perfusate. Serial (0-90 min) perfusate and bile and terminal liver samples were collected for analysis by HPLC. In the Control livers, 25.4 +/- 2.2% (mean +/- SD) of the dose was recovered as RH-123 (11.7 +/- 2.0%) and RH-Glu (13.2 +/- 0.9%) in the bile. Whereas CyA substantially (90%) reduced (p < 0.001) the biliary excretion of RH-123 without affecting the excretion of RH-Glu, DBSP reduced the biliary excretion of RH-Glu by >80% (p < 0.001) with no effect on the biliary excretion of RH-123. Mass balance studies showed that DBSP, in addition to reducing the biliary clearance of RH-Glu, also strongly inhibited the glucuronidation of RH-123, an effect that was confirmed in vitro using the glucuronidation marker umbelliferone. It is concluded that the use of RH-123 in an IPRL model may serve as a dual marker for the determination of the altered functions of P-gp and/or Mrp2.
authors.affiliation: School of Pharmacy, Texas Tech University Health Sciences Center, 1300 Coulter, Amarillo, Texas 79106, USA.
authors.forename: Ridhi
authors.initials: R
authors.lastname: Parasrampuria
authors.forename: Reza
authors.initials: R
authors.lastname: Mehvar
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors* / Q000502:physiology; D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors* / Q000502:physiology; D000818:Animals; D001659:Biliary Tract / Q000187:drug effects / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D016572:Cyclosporine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005456:Fluorescent Dyes / Q000493:pharmacokinetics*; D020719:Glucuronides / Q000378:metabolism*; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley; D020112:Rhodamine 123 / Q000378:metabolism / Q000493:pharmacokinetics*; D013448:Sulfobromophthalein / Q000494:pharmacology; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; C423013:Abcc2 protein, rat; D005456:Fluorescent Dyes; D020719:Glucuronides; D013448:Sulfobromophthalein; C012479:dibromosulphthalein; D020112:Rhodamine 123; D016572:Cyclosporine