title: Effect of PSC 833, a P-glycoprotein modulator, on the disposition of vincristine and digoxin in rats.
abstract: PSC 833 has been used to overcome the phenomenon of multidrug resistance by inhibiting the P-glycoprotein (P-gp)-mediated efflux of antitumor drugs from tumor cells. Because P-gp expressed in several normal tissues may affect the disposition of its substrates, we examined the dose-dependent effect of PSC 833 on the disposition of vincristine (VCR) and digoxin (DGX) in rats. One-tenth milligram per kilogram PSC 833 was sufficient to significantly reduce the biliary excretion clearance of DGX from 3.0 ml/min/kg to 0.5 ml/min/kg, whereas 3 mg/kg PSC 833 was needed to significantly reduce the biliary excretion clearance of VCR from 36 ml/min/kg to 9 ml/min/kg. Three milligrams per kilogram PSC 833 significantly reduced the renal clearance of VCR by 30% but did not affect that of DGX significantly. The tissue-to-plasma DGX concentration ratio in the brain at 6 h after administration (0.34 versus 1.64), but not that of VCR at 2 h (1.07 versus 1.37), was significantly increased by PSC 833, 3 mg/kg. The differential effect of PSC 833 on the disposition of VCR and DGX may be ascribed to the different degree of contribution of P-gp to the disposition of these ligands.
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Song
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
authors.forename: R
authors.initials: R
authors.lastname: Kawai
authors.forename: Y
authors.initials: Y
authors.lastname: Sugiyama
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000493:pharmacokinetics*; D000972:Antineoplastic Agents, Phytogenic / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D019540:Area Under Curve; D001646:Bile / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003524:Cyclosporins / Q000494:pharmacology*; D004077:Digoxin / Q000493:pharmacokinetics*; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D005260:Female; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured; D014750:Vincristine / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000889:Anti-Arrhythmia Agents; D000972:Antineoplastic Agents, Phytogenic; D003524:Cyclosporins; D014750:Vincristine; D004077:Digoxin; C070272:valspodar