Mechanisms of gemcitabine oral absorption as determined by in situ intestinal perfusions in mice

Copyright © 2019 Elsevier Inc. All rights reserved..

Gemcitabine is a widely used chemotherapeutic drug that is administered via intravenous infusion due to a low oral bioavailability of only 10%. This low oral bioavailability is believed to be the result of gemcitabine's low intestinal permeability and oral absorption, followed by significant presystemic metabolism. In the present study, we sought to define the mechanisms of gemcitabine intestinal permeability, the potential for saturation of intestinal uptake, and the transporter(s) responsible for mediating the oral absorption of drug using in situ single-pass intestinal perfusions in mice. Concentration-dependent studies were performed for gemcitabine over 0.5-2000 μM, along with studies of 5 μM gemcitabine in a sodium-containing buffer ± thymidine (which can inhibit concentrative (i.e., CNT1 and CNT3) and equilibrative (i.e., ENT1 and ENT2) nucleoside transporters) or dilazep (which can inhibit ENT1 and ENT2), or in a sodium-free buffer (which can inhibit CNT1 and CNT3). Our findings demonstrated that gemcitabine was, in fact, a high-permeability drug in the intestine at low concentrations, that jejunal uptake of gemcitabine was saturable and mediated almost exclusively by nucleoside transporters, and that jejunal flux was mediated by both high-affinity, low-capacity (Km = 27.4 µM, Vmax = 3.6 pmol/cm2/s) and low-affinity, high-capacity (Km = 700 µM, Vmax = 35.9 pmol/cm2/s) transport systems. Thus, CNTs and ENTs at the apical membrane allow for gemcitabine uptake from the lumen to enterocyte, whereas ENTs at the basolateral membrane allow for gemcitabine efflux from the enterocyte to portal venous blood.

Medienart:

E-Artikel

Erscheinungsjahr:

2019

Erschienen:

2019

Enthalten in:

Zur Gesamtaufnahme - volume:168

Enthalten in:

Biochemical pharmacology - 168(2019) vom: 15. Okt., Seite 57-64

Sprache:

Englisch

Beteiligte Personen:

Thompson, Brian R [VerfasserIn]
Hu, Yongjun [VerfasserIn]
Smith, David E [VerfasserIn]

Links:

Volltext

Themen:

0W860991D6
Cif nucleoside transporter
Concentrative nucleoside transporters
Deoxycytidine
Dilazep
Equilibrative Nucleoside Transport Proteins
Equilibrative nucleoside transporters
F8KLC2BD5Z
Gemcitabine
Intestinal permeability
Journal Article
Membrane Transport Proteins
Research Support, N.I.H., Extramural
Saturation kinetics
Thymidine
VC2W18DGKR

Anmerkungen:

Date Completed 13.07.2020

Date Revised 07.12.2022

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.bcp.2019.06.013

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM298236982