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Role of P-glycoprotein and cytochrome P450 3A in limiting oral absorption of peptides and peptidomimetics.
Cytochrome P450 3A4 (CYP3A4), the major phase I drug metabolizing enzyme in humans, and the MDR1 gene product P-glycoprotein (P-gp) are present at high concentrations in villus tip enterocytes of theExpand
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Differentiation of absorption and first‐pass gut and hepatic metabolism in humans: Studies with cyclosporine
The low and variable bioavailability of cyclosporine has been attributed to poor absorption. However, recent studies have suggested that intestinal first‐pass metabolism exerts a significant effectExpand
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The effects of ketoconazole on the intestinal metabolism and bioavailability of cyclosporine
The pharmacokinetics of cyclosporine were studied in the blood of five normal healthy volunteers (two men and three women) after each received oral and intravenous cyclosporine alone and withExpand
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Evaluation of peppermint oil and ascorbyl palmitate as inhibitors of cytochrome P4503A4 activity in vitro and in vivo
Our study was designed to determine the effect of peppermint oil and ascorbyl palmitate on cytochrome P4503A4 (CYP3A4) activity in vitro and oral bioavailability of felodipine in humans.
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Grapefruit Juice Activates P-Glycoprotein-Mediated Drug Transport
AbstractPurpose. Grapefruit juice (GJ) is known to increase the oral bioavailability of many CYP3A-substrates by inhibiting intestinal phase-I metabolism. However, the magnitude of AUC increase isExpand
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Intestinal drug metabolism and antitransport processes : A potential paradigm shift in oral drug delivery
Poor oral bioavailability for many drugs is generally attributed to poor solubility in the gastrointestinal fluids, poor gut membrane permeability and/or extensive hepatic first-pass elimination.Expand
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Peppermint oil enhances cyclosporine oral bioavailability in rats: comparison with D-alpha-tocopheryl poly(ethylene glycol 1000) succinate (TPGS) and ketoconazole.
Peppermint oil inhibits cyclosporine metabolism in vitro. The current work compared the effects of peppermint oil, ketoconazole, and D-alpha-tocopheryl poly(ethylene glycol 1000) succinate (TPGS) onExpand
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Pharmacokinetics of tamoxifen after intravenous and oral dosing of tamoxifen-hydroxybutenyl-beta-cyclodextrin formulations.
Oral and intravenous administration of tamoxifen base and tamoxifen citrate formulated with hydroxybutenyl-beta-cyclodextrin (HBenBCD) to Sprague-Dawley rats significantly increased the oralExpand
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Sirolimus Oral Absorption in Rats Is Increased by Ketoconazole but Is Not Affected by d-α-Tocopheryl Poly(Ethylene Glycol 1000) Succinate
The contributions of cytochrome P450 3A (CYP3A) and P-glycoprotein to sirolimus oral bioavailability in rats were evaluated by coadministration of sirolimus (Rapamune) with the CYP3A inhibitorExpand
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