title: Hepatic and intestinal first-pass effects of oltipraz in rats.
abstract: It was reported that the mean value of the extent of absolute oral bioavailability (F) of oltipraz at a dose of 20 mg/kg was 41.2% and only 2.68% of the oral dose was unabsorbed from the gastrointestinal tract in rats. Hence, the low F in rats could be due to considerable first-pass (gastric, intestinal and hepatic) effects. Hence, the first-pass effects of oltipraz were measured after intravenous, intraportal, intragastric and intraduodenal administration of the drug at a dose of 20 mg/kg to rats. The total area under the plasma concentration-time curve from time zero to time infinity (AUC) values between intragastric and intraduodenal administration (213 and 212 microg min/ml) in rats were almost similar, but the values were significantly smaller than that after intraportal administration (316 microg min/ml) in rats, indicating that gastric first-pass effect was almost negligible (due to negligible absorption of oltipraz from rat stomach), but the intestinal first-pass effect of oltipraz was considerable, approximately 32% of the oral dose. The hepatic first-pass effect of oltipraz was approximately 40% based on AUC values between intravenous and intraportal administration (319 versus 536 microg min/ml). Since approximately 65% of the oral oltipraz was absorbed into the portal vein, the value of 40% was equivalent to 25% of the oral dose. The low F of oltipraz in rats was mainly due to considerable hepatic and intestinal first-pass effects.
authors.affiliation: College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, San 56-1, Shinlim-Dong, Kwanak-Gu, Seoul 151-742, Republic of Korea.
authors.forename: Soo K
authors.initials: SK
authors.lastname: Bae
authors.forename: Jin W
authors.initials: JW
authors.lastname: Kim
authors.forename: Young H
authors.initials: YH
authors.lastname: Kim
authors.forename: Yoon G
authors.initials: YG
authors.lastname: Kim
authors.forename: Sang G
authors.initials: SG
authors.lastname: Kim
authors.forename: Myung G
authors.initials: MG
authors.lastname: Lee
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001646:Bile / Q000378:metabolism; D001682:Biological Availability; D004386:Duodenum; D005753:Gastric Mucosa / Q000378:metabolism; D007275:Injections, Intravenous; D007413:Intestinal Mucosa / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D008657:Metabolic Clearance Rate; D011169:Portal Vein; D011719:Pyrazines / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013871:Thiones; D013876:Thiophenes; D014018:Tissue Distribution
chemical_list: D011719:Pyrazines; D013871:Thiones; D013876:Thiophenes; C026209:oltipraz