Erythrocyte binding of cephalosporins

A rapid sample preparation and HPLC technique was used to study the erythrocyte binding properties of six cephalosporins at therapeutic concentrations. The negligible red blood cell partition coefficients indicated that only small amounts of the cephalosporins were taken up by the blood cells at all drug concentrations. Thus, plasma concentrations were about twice as high as the respective blood concentrations. Blood/plasma ratios solely depended on the haematocrit and were independent of the extent of protein binding.