Methods of drug protein binding determinations

The determination of drug binding to proteins is carried out by several different approaches based mainly on separation methods. The most popular of these is equilibrium dialysis, which requires membranes devoid of non-specific adsorption to drugs. Ultrafiltration techniques have some advantage over dialysis due to shorter measurement times and the possibility of evaluation of the free drug under circumstances corresponding to physiological conditions. Now there is an increasing use of chromatographic techniques for fundamental studies on determination of binding parameters (number of sites, affinity constant). Different procedures can be chosen depending upon the biological materials available. They are based on the presence of the interacting species in the eluent, avoiding any chemical grafting.