Drug-protein interaction: the binding of cephalosporins to albumins.

The binding of some cephalosporin antibiotics, namely cephalothin, cephaloridine and cephalexin, to serum albumins was quantitized using a fluorescence probe technique. The results suggest that these drugs bind to hydrophobic sites on serum albumins. The association constants of the three drugs with bovine serum albumin showed the strongest binding for cephalothin (Ka 1.2 x 10(3) M(1)) and weaker ones for cephaloridine and cephalexin (Ka 0.59 and 0.4 x 10(3) M(-1)). Serum albumin from different species was also investigated, only minor variations in the binding properties being found.