Intestinal absorption of several beta-lactam antibiotics. V. Effect of amino beta-lactam analogues and dipeptides on the absorption of amino beta-lactam antibiotics.

The absorption mechanism of amino beta-lactam antibiotics was investigated by using the whole small intestine of a rat. Mutual inhibition among amino beta-lactam analogues and the effects of dipeptides were studied. The influences of glycylglycine on the absorption of cephradine at the four different parts of intestine were also studied. Similarly to the case of cephalexin and cephradine, the absorption of amoxicillin was significantly inhibited by cyclacillin, cephradine, and cephalexin, but the absorption of ampicillin was not reduced by all tested antibiotics. In the experiments using dipeptides (6.0 mM), the absorption of cyclacillin was reduced significantly by glycylglycine, not by L-carnosine. And cephalexin absorption was influenced by L-carnosine (6.0, 10 mM), not by glycylglycine (6 mM). On the contrary, the absorption of cephradine was not reduced at all by these dipeptides. And from the experiment using the four different parts of intestine, it was shown that the transport interaction of glycylglycine with cephradine was observed in only one segment (the upper part of jejunum). These result suggest that the carrier-mediated transport system correlated to dipeptides participates only to a small degree in the common absorption mechanisms of these amino beta-lactam antibiotics.