Comparison of drug binding sites on rat and human serum albumins using immobilized-protein stationary phases as a tool for the selection of suitable animal models in pharmacological studies.

Immobilized serum albumins (rat and human) HPLC stationary phases have been used to investigate and to compare the binding sites of a number of analytes of pharmaceutical interest assessing the retention time as the chromatographic parameter which correlates the percentage of drug-binding of the corresponding free protein. Anti-inflammatory drugs with different molecular structure were chromatographed and the k' values were determined with a mobile phase based on 100 mM sodium phosphate buffer (pH 6.9) containing 6% n-propanol (v/v). The effect of the addition to the mobile phase of octanoic, decanoic and dodecanoic acids on the k' values enabled to elucidate the site of interaction between the solutes and the two albumins. The results indicate that there are some structural differences in the binding sites of the two albumins and also some quantitative differences with respect to the extent of drug-binding. Moreover the different stereoselective behaviour of the two albumins was studied by analysing some chiral anti-inflammatory drugs much as aryl-propionic acids.