ACTIVE SECRETION OF THE FLUOROQUINOLONE CIPROFLOXACIN BY HUMAN INTESTINAL EPITHELIAL CACO-2 CELL-LAYERS

The bidirectional transepithelial fluxes of ciprofloxacin, an antibacterial fluoroquinolone, across the human intestinal epithelial Caco-2 cell-line show marked asymmetry. Basal-to-apical flux of ciprofloxacin (10 muM) exceeds apical-to-basal flux indicating net secretion. Net ciprofloxacin secretion is abolished by azide/2-deoxy-D-glucose treatment, displays saturation kinetics (K(m) = 0.89 +/- 0.23 mm, V(max) 44.3 +/- 4.9 nmol cm-2 . h) and competition by other fluoroquinolones. A specific, active secretion in Caco-2 epithelia may explain the transintestinal elimination of ciprofloxacin observed in pharmacokinetic studies in man.