Measurement of human plasma protein binding

Method Description

This in vitro method is used to determine the fraction of a chemical bound to human plasma proteins. Plasma protein binding is measured using in vitro approaches, where test chemicals are incubated with pooled human plasma and the unbound fraction is quantified analytically. The method provides information on the freely available fraction of a chemical in blood, which influences distribution, clearance, and overall toxicokinetics.

This method was selected together with the intrinsic hepatic clearance method and a defined approach for toxicokinetic interpretation, as part of a single project submitted to the OECD Test Guidelines Programme. The combined use of these methods enables the derivation of key human toxicokinetic parameters such as biological half-life, steady-state blood concentration (Css), and area under the concentration–time curve (AUC).