RT Journal Article SR Electronic T1 Integrated Approach of In Vivo and In Vitro Evaluation of the Involvement of Hepatic Uptake Organic Anion Transporters in the Drug Disposition in Rats Using Rifampicin as an Inhibitor JF Drug Metabolism and Disposition JO Drug Metab Dispos FD American Society for Pharmacology and Experimental Therapeutics SP 1442 OP 1449 DO 10.1124/dmd.113.051052 VO 41 IS 7 A1 Tomoki Imaoka A1 Tsuyoshi Mikkaichi A1 Koji Abe A1 Masakazu Hirouchi A1 Noriko Okudaira A1 Takashi Izumi YR 2013 UL http://dmd.aspetjournals.org/content/41/7/1442.abstract AB Cumulative studies describe the importance of drug transporters as one of the key determinants of pharmacokinetics that necessitate investigation and assessment of the involvement of drug transporters in drug discovery and development. The present study investigated an integrated in vivo and in vitro approach to determine the involvement of organic anion transporting polypeptides (Oatps) in the disposition of drugs in rats using rifampicin as an inhibitor. When bromosulfophthalein (BSP) and HMG-CoA reductase inhibitors (statins), which were used as model substrates for Oatps, were administered intravenously (3 and 1 mg/kg, respectively) to rats pretreated with rifampicin orally (30 mg/kg), the total plasma clearance of BSP and statins was attenuated compared with that in control rats, suggesting the involvement of Oatps in the disposition of these drugs in vivo. On the other hand, the pharmacokinetics of midazolam, used as a model substrate of cytochrome P450 3a (Cyp3a), was unchanged between control rats and rifampicin-pretreated rats. The involvement of Oatps in the disposition of statins observed in vivo was further clarified by employing an in vitro hepatic uptake study and media-loss assay in the presence or absence of 100 μM rifampicin. Hepatic intrinsic clearance was reduced in the presence of rifampicin in both the media-loss assay and hepatocyte uptake study. The present study suggests in vivo investigations in rats using rifampicin together with in vitro investigations with a media-loss assay and/or uptake assay using rat hepatocytes can help determine whether a clinical drug-drug interaction study is necessary in drug development.