Dose-dependent inhibition of transporter-mediated hepatic uptake and biliary excretion of methotrexate by cyclosporine A in an isolated perfused rat liver model
✍ Scribed by Ridhi Parasrampuria; Reza Mehvar
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 192 KB
- Volume
- 99
- Category
- Article
- ISSN
- 0022-3549
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✦ Synopsis
Methotrexate (MTX) and cyclosporine (CyA) are coadministered in a number of diseases. In this study, the effects of CyA on the hepatobiliary disposition of MTX were investigated in an isolated perfused rat liver model. A bolus 5-mg dose of MTX was added to a recirculating perfusate in the absence or presence of a relatively low (0.5 mg) or high (2.5 mg) dose of CyA or vehicle pretreatment, and perfusate, bile, and terminal liver samples were collected for analysis by high-performance liquid chromatography (HPLC). In control and vehicle groups, MTX showed a low hepatic extraction ratio ($0.1) and was almost completely eliminated by excretion into the bile. The low-dose CyA significantly reduced (60%) the hepatic extraction ratio and clearance of MTX, without affecting the bile/liver concentration ratio, suggesting inhibition of sinusoidal uptake of MTX only. In contrast, the high-dose CyA significantly reduced both hepatic uptake and Mrp2-mediated biliary excretion of MTX. Isolated rat hepatocyte uptake studies showed significant inhibition of [ 3 H]MTX uptake in the presence of CyA. It is concluded that CyA significantly alters the hepatobiliary disposition of MTX by inhibiting its sinusoidal uptake and/or biliary transport, potentially reducing enterohepatic recirculation of the drug in vivo.