Determination of the extent of protein binding of antibiotics by means of an automated continuous ultrafiltration method.

The extent of the protein binding of a drug is an important pharmacokinetic parameter. In this study, the determination of the protein binding of the antibiotics gatifloxacin, moxifloxacin, linezolid and telithromycin to bovine serum albumin (BSA) and human serum albumin (HSA) was performed by means of an automated continuous ultrafiltration method. The continuous ultrafiltration has several advantages compared to classical methods like equilibrium dialysis or discontinuous ultrafiltration. The method is appropriate for a fast determination of the extent of the protein binding of a drug. In one single experiment the calculation of the protein binding over a wide range of different drug/protein ratios is possible. Comparing the results obtained with the continuous ultrafiltration with binding data reported in literature shows good correlation and proves the reliability of the method.