Accumulation and Oriented Transport of Ampicillin in Caco-2 Cells from Its Pivaloyloxymethylester Prodrug, Pivampicillin

Abstract

Pivampicillin (PIVA), an acyloxymethylester of ampicillin, is thought to enhance the oral bioavailability of ampicillin because of its greater lipophilicity compared to that of ampicillin. The fate of PIVA in intestinal cells and the exact location of its conversion into ampicillin have, however, never been unambiguously established. Polarized Caco-2 cells have been used to examine the handling of PIVA and the release of ampicillin from PIVA by the intestinal epithelium. Experiments were limited to 3 h. Cells incubated with PIVA (apical pole) showed a fast accumulation of ampicillin and transport toward the basolateral medium, whereas PIVA itself was only poorly accumulated and transported. Cells incubated with free ampicillin accumulated and transported only minimal amounts of this drug. Release of ampicillin from cells incubated with PIVA was unaffected by PEPT1 and OCTN2 inhibitors but was sharply decreased after ATP depletion or addition of bis(4-nitrophenyl)-phosphate (BNPP; an esterase inhibitor). PIVA incubated with Caco-2 lysates released free ampicillin, and this release was inhibited by BNPP. Efflux studies showed that the ampicillin that accumulated in cells after incubation with PIVA was preferentially transported out of the cells through the basolateral pole. This efflux was decreased by multidrug resistance-associated protein (MRP) inhibitors (probenecid, MK-571) and by ATP depletion. A phthalimidomethylester of ampicillin that resists cellular esterases failed to cause any significant release (cell lysate) or transport (polarized Caco-2 cells) of ampicillin. These results show that when PIVA is given to Caco-2 cells from their apical pole, ampicillin is released intracellularly and that ampicillin is thereafter preferentially effluxed into the basolateral medium through an MRP-like transporter.

Cross-Species Differences in the Preclinical Pharmacokinetics of CT7758, an α4β1/α4β7 Integrin Antagonist

“…Also, these data should be interpreted with caution, because CDP323 might have been partially hydrolyzed during the assay. Indeed, hydrolytic enzymes can be released from Caco-2 brush border membranes, as reported elsewhere (Chanteux et al, 2005;Brouwers et al, 2007;Yuan et al, 2009).…”

Bacampicillin Uptake Is Shared with Thiamine in Caco-2 Cells

“…Therefore the absorption mechanisms of these ampicillin prodrugs have not been fully investigated until now. Recently, Chanteux et al 18) reported that pivampicillin, which was added to the apical side of Caco-2 cells, was efficiently hydrolyzed to ampicillin inside the cells and that the ampicillin was preferentially released to the basolateral medium via an MRP-like transporter. The aim of this study was to assess how Caco-2 cells deal with bacampicillin as compared with pivampicillin.…”

“…It was also thought that pivampicillin was easily converted to ampicillin in the Caco-2 cells, which is consistent with results presented in recent papers. 18,19) Because an Eadie-Hofstee plot (Fig. 2) implied possible involvement of a specialized transport system for bacampicillin, the changes in its uptake were investigated in the presence of various organic cations.…”

The overexpression of MRP4 is related to multidrug resistance in osteosarcoma cells

“…ucl.ac.uk/nomenclalure/genefamily/abc.html). In polarized cells, MRPs localize to either the basolateral membrane (which may increase drug absorption) [6,7] or apical membrane (which enhance drug elimination). In non-polarized cells, such as transporters, MRPs pump intracellular drugs out, resulting in a decrease in drug concentration.…”

“…This inhibits the progression of the enzyme topoisomerase II, which relaxes supercoils in DNA leading to transcription. [6,16] A series of cancer cell lines have been used to study doxorubicin resistance. However, there is no data regarding osteosarcoma cells.…”