Research On The Characteristics Of Transepithelial Transport Of Cefditoren In Vivo And In Vitro

Objective: H+/oligopeptide cotransporter PEPT1, mainly located at the brush border membrane of intestinal epithelium cell, transport dipeptide/ tripeptide which is the degradation products of protein in digestive tract. Peptide-like drugs such asβ-lactam antibiotics,angiotensin-converting enzyme inhibitor (ACEI) and non-peptide drugs valaciclovir also can be transported via PEPT1. PEPT1 is important for maintaining the homeostasis and the absorption of drugs in gastrointestinal tract. In this study, the effects of glycylsarcosine and clonidine on uptake and transepithelial transport of cefditoren were investigated in vivo and in vitro, to clarify whether cefditoren is a potential substract of PEPT1/ PEPT2.Methods: Rats were administered cefditoren(10mg/kg) by intravenous administration, in the absence and presence of glycylsarcosine. Serial urine and bile samples were obtained in the period of 60 minuts. The effects of Gly-Sar and clonidine on transport activities was measured by everted small intestinal preparations or in situ intestinal loop technique. Uptake of cefditoren in Caco-2 cells was examined with or without Gly-Sar. Effects of pH and temperature on CDTR transport was also examined in Caco-2 cells. The concentration of cefditoren was determined by HPLC.Results: In vivo Gly-Sar coadministration increased the renal clearance of cefditoren by 200% as compared to cefditoren alone. The intestinal cefditoren absorption rate was decreased when Gly-Sar was dissolved in the perfusate at a concentration of 50mM. Before intrajejunal perfusion , intravenous infusing clonidine(400μg/kg) induced a 50% increase of cefditoren absorption across the intestinal mucosa. Saturable intestinal uptake of cefditoren was found using the everted jejunum of rats. The competitively inhibitive effect of Gly-Sar(200mM) on transport of cefditoren was consistant with that of in situ intrajujunal perfusion. Uptake of cefditoren was decreased by Gly-Sar in caco-2 cells as compared to cefditoren alone. pH and temperature significantly influence cefditoren uptake in Caco-2 cells, Km=1.095mM,Vmax=1.115nmol/mg protein/30min. The maximal uptake of cefditoren was found at pH= 6.0.Conclusion: This study provides the first evidence, under in vivo and in vitro conditions, that Gly-Sar and clonidine affect the transepithelial transport of cefditoren. The results demonstrate that cefditoren is the potential substract of the H+/oligopeptide cotransporter PEPTs.