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Nonlinear absorption of methylprednisolone by absorptive and secretory transporters

Mikio Tomita1, Atsuko Watanabe, Ikue Fujinaga

  • 1Department of Drug Absorption and Pharmacokinetics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan. tomita@ps.toyaku.ac.jp

International Journal of Pharmaceutics
|November 4, 2009
PubMed

Insights

Methylprednisolone intestinal absorption involves carrier-mediated transport and P-glycoprotein secretion. Its complex, nonlinear absorption is due to multiple intestinal transport mechanisms.

Area of Science:

  • Pharmacology
  • Gastroenterology
  • Biophysics

Background:

  • Methylprednisolone (MP) is a widely used corticosteroid with complex intestinal absorption.
  • Understanding its transport mechanisms is crucial for optimizing drug delivery and efficacy.

Purpose of the Study:

  • To elucidate the intestinal transport mechanisms of methylprednisolone (MP).
  • To investigate the role of carrier-mediated transport and P-glycoprotein (P-gp) in MP absorption and secretion.

Main Methods:

  • Intestinal absorption rate constant determination using the loop method.
  • In vitro permeation studies across rat jejunal sheets.
  • Vectorial transport assessment across Caco-2 cell monolayers.
  • Evaluation of P-gp involvement using specific inhibitors.

Main Results:

  • MP intestinal absorption showed nonlinear kinetics, increasing with concentration up to 500 microM.
  • Mucosal-to-serosal permeation increased at low concentrations then decreased, while serosal-to-mucosal permeation decreased concentration-dependently.
  • Vectorial transport was observed in Caco-2 cells, predominantly basolateral-to-apical.
  • P-gp inhibitors affected absorptive and secretory clearance, indicating P-gp's role in MP secretion.

Conclusions:

  • Intestinal transport of MP involves carrier-mediated uptake and P-gp-mediated secretion.
  • Multiple transport systems contribute to the complex, nonlinear intestinal absorption of MP.
  • P-glycoprotein plays a predominant role in the intestinal secretion of methylprednisolone.

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