Measurements of plasma protein binding – variety of experimental techniques

Abstract

Drug molecules in vivo may be bound to proteins and lipids in plasma and/or in tissues, or free (unbound) in diffusion among the aqueous environment of the blood and tissues. Data from in vitro plasma protein binding experiments that determine the fraction of protein-bound drug are frequently used in drug discovery. Methods used for drug – plasma protein binding (PPB) studies are numerous and can be divided into two main groups: separation methods (enabling the calculation of binding parameters, i.e. the number of binding sites and their respective affinity constants) and non-separation methods (describing predominantly qualitative parameters of the ligand-protein complex).