New Methods to Evaluate Intestinal Drug Absorption Mediated by Oligopeptide Transporter from In vitro Study using Caco-2 Cells

• Published in: DRUG METABOLISM AND PHARMACOKINETICS 2002, Vol.17 (5), p.408-415
• Main Authors: Yamashita, Shinji, Hattori, Emiko, Shimada, Aiko, Endoh, Yoriko, Yamazaki, Yukako, Kataoka, Makoto, Sakane, Toshiyasu, Sezaki, Hitoshi
• Format: Article
• Language: English
• Subjects: Caco-2 monolayers; competitive inhibition; cotransport; drug permeability; oligopeptide transporter
• ISSN: 1347-4367; 1880-0920
• DOI: 10.2133/dmpk.17.408

The aim of the present work is to develop a convenient and rapid screening system in vitro for intestinal drug absorption mediated by oligopeptide transporter (PepT1). In this study, (1) Transports of cephalexin (CEX) and L-phenylalanine (L-Phe) across Caco-2 monolayers were measured and compared with those of passively transported drugs, (2) Inhibitory effects of various drugs on the transport of [14C]glycylsarcosine (Gly-Sar) across Caco-2 monolayers were measured and correlated with their in vivo permeability to rat small intestine, (3) Intracellular pH-change induced by co-transport of drugs with proton into Caco-2 cells was monitored by using Fluorometric Imaging Plate Reader (FLIPR, Molecular Devices Corp.). Concentration-dependent transport was observed in Caco-2 monolayers for CEX and L-Phe, although their permeability was relatively low compared to those of passively transported drugs. Inhibitory effects of various drugs including β-lactam antibiotics and angiotensin converting enzyme-inhibitors on the transport of Gly-Sar correlated well with their in vivo permeability to rat small intestine. It was demonstrated that CEX, but not cefazolin, induced gradual decrease in the intracellular pH of Caco-2 cells. The degree of intracellular pH-change caused by various drugs showed a sigmoidal or saturable relationship with their permeability to rat small intestine. These in vitro approaches with Caco-2 cells should be useful to evaluate in vivo intestinal permeability of drugs mediated by PepTl, suggesting a possibility of high throughput screening of drug absorption.