Transport characteristics of ceftibuten, cefixime and cephalexin across human jejunal brush-border membrane.

The transport characteristics of orally active cephalosporins, ceftibuten, cefixime and cephalexin have been examined using brush border membrane vesicles isolated from human jejunum. In the initial uptake of ceftibuten, the stimulation and overshoot phenomena were observed in the presence of an inward H+ gradient. Effects of H+ gradient on the uptake of cefixime and cephalexin were low and no overshoot was observed. These transport characteristics, especially uphill transport phenomena, were in agreement with previous results obtained from rat intestinal brush-border membrane vesicles and suggest that these beta-lactam antibiotics are absorbed by different transport systems, despite their similar molecular structures.