Intestinal absorption of several .BETA.-lactam antibiotics. III. Competitive inhibition behavior among zwitterionic .BETA.-lactam antibiotics in the rat intestinal absorption.

Abstract

Competitive inhibitory behavior among zwitterionic .beta.-lactam antibiotics in the rat intestinal absorption process was examined. Intestinal absorption of cephradine and cephalexin was significantly inhibited by cyclacillin. The mutual inhibition between these amino-cephalosporins was also observed. In pretreatment experiments with cyclacillin, absorption of cephradine was significantly inhibited, but the inhibitory effect of cyclacillin was not observed for cephalexin. Apparently, cephradine had a common carrier-mediated transport mechanism with cyclacillin which is not present in the absorption process of cephalexin. The mutual inhibiton between cephradine and cephalexin may be based on the competitive inhibition in the accumulation or uptake by the intestinal mucosa.