title: GI absorption of beta-lactam antibiotics. III: Kinetic evidence for in situ absorption of ionized species of monobasic penicillins and cefazolin from the rat small intestine and structure-absorption rate relationships.
abstract: Absorption rates of monobasic beta-lactam antibiotics were measured as a function of lumen solution pH between 4 and 9 by utilizing the rat intestinal recirculating method in situ. Between pH 6.5 and 9, the absorption rate constants of ionized antibiotics were almost identical; but, at pH 4, the unionized species were highly absorbed, depending on their lipophilicity through the GI membrane lipoidal barrier. The structure-absorption rate relationship was established with the unstirred layer model.
mesh_terms: D000818:Animals; D001711:Biotransformation; D002437:Cefazolin / Q000378:metabolism*; D002511:Cephalosporins / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption; D007421:Intestine, Small / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D010406:Penicillins / Q000378:metabolism*; D051381:Rats; D013329:Structure-Activity Relationship
chemical_list: D002511:Cephalosporins; D010406:Penicillins; D002437:Cefazolin