Contribution of passive transport mechanisms to the intestinal absorption of beta-lactam antibiotics.
The transport characteristics of aminopenicillins (ampicillin and amoxicillin), aminocephalosporins (cephalexin, cephradine and cefadroxil) and cefazolin have been compared with those of an actively transported substance (D-glucose) and a passively transported substance (L-glucose). Although the initial uptake of the aminocephalosporins was stimulated in the presence of an inward H+ gradient, there was no overshoot in the uptake of any of the drugs tested, even in the presence of an H+ gradient. Also, the time course and the degree of uptake of these drugs were similar to those of L-glucose, especially in the absence of an H+ gradient. These results suggest that the beta-lactam antibiotics tested, like L-glucose, pass through the rat intestinal brush border membrane mainly by passive diffusion. However, the differences in absorption between these drugs, like the differences in their disappearance from a proximal loop of rat intestine, cannot be explained by a simple permeation process alone.
Sugawara
M
M
Department of Pharmacy, Hokkaido University Hospital, School of Medicine, Sapporo, Japan.
Saitoh
H
H
Iseki
K
K
Miyazaki
K
K
Arita
T
T
D000818:Animals; D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics*; D001692:Biological Transport; D002511:Cephalosporins / Q000493:pharmacokinetics; D005947:Glucose / Q000378:metabolism; D066298:In Vitro Techniques; D007408:Intestinal Absorption; D008297:Male; D010406:Penicillins / Q000493:pharmacokinetics; D051381:Rats; D011919:Rats, Inbred Strains
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D010406:Penicillins; D005947:Glucose