Metal cation-fluoroquinolone complexes do not permeate through the intestinal absorption barrier.

A case of a clinically significant interaction between a fluoroquinolone antimicrobial agent and metal cations was first reported in 1985. The hypothesized mechanism--decreased fluoroquinolone intestinal permeability due to complex formation between metal cations and ciprofloxacin--was based on a 1978 work with nalidixic acid. While clinical research and numerous in vitro physico-chemical and chelation chemistry studies of fluoroquinolone-metal cation combinations simply accepted this explanation, the few in vitro studies, which were aimed to investigate the nature of the interaction mechanism, provided conflicting results.

Influence of luminal monosaccharides on secretion of glutathione conjugates from rat small intestine in vitro.

Intestinal efflux transporters can significantly reduce the absorption of the drug after peroral application. In this work we studied secretion of glutathione conjugates triggered by glucose at the luminal side of the intestine. Glucose stimulated secretion of DNPSG, NEMSG and CDNB.

Aged garlic extract stimulates p-glycoprotein and multidrug resistance associated protein 2 mediated effluxes.

The growing concomitant consumption of drugs and herbal preparations such as garlic, and the numerous reports about the influence of herbal preparations on intestinal transport, led us to evaluate the influence of aged garlic extract on the transport function and electrophysiological parameters of the small intestinal mucosa. Aged garlic extract induced increase of the absolute value of the transepithelial potential difference and of the short-circuit current in both permeability models tested (rat jejunum, Caco-2 cell monolayers) without affecting transepithelial electrical resistance. It also caused a significant increase of the P-glycoprotein and multidrug resistance associated protein 2 mediated effluxes through rat jejunum of marker substrates Rhodamine 123 and 2,4-dinitrophenyl-S-glutathione, respectively.

Fluorescein transport properties across artificial lipid membranes, Caco-2 cell monolayers and rat jejunum.

Membrane transport characteristics of a paracellular permeability marker fluorescein were evaluated using artificial membrane, Caco-2 cell monolayers and rat jejunum, all mounted in side-by-side diffusion cells. Modified Ringer buffers with varied pH values were applied as incubation salines on both sides of artificial membrane, cell culture monolayers or rat jejunum. Passive transport according to pH partition theory was determined using all three permeability models.