Role of monocarboxylic acid transporters in the cellular uptake of NSAIDs.

The present study investigated the cellular uptake mechanism of non-steroidal anti-inflammatory drugs (NSAIDs) in Caco-2 cells. Diflunisal, diclofenac, ketoprofen and naproxen exhibited a strong inhibition effect on the cellular uptake of [14C]-benzoic acid in Caco-2 cells with IC50 values of 0.05-0.44 mM. The inhibition of naproxen and ketoprofen against the membrane transport of [14C]-benzoic acid appeared to be competitive, with Ki values of 0.22 and 0.38 mM, respectively. The membrane permeability of naproxen and ketoprofen was concentration dependent, implying that the cellular uptake pathway of ketoprofen and naproxen was saturable at the higher concentration. Furthermore, the cellular accumulation of ketoprofen was significantly reduced in the presence of benzoic acid and L-lactic acid, two known substrates of monocarboxylic acid transporter 1 (MCT1). These results suggest that MCT1 contributes at least in part to the carrier-mediated transport of NSAIDs containing a carboxylic acid moiety across the apical membrane in Caco-2 cells.