Plasma Protein Binding

Streamlined Plasma Protein Binding Assessment Using Rapid Equilibrium Dialysis

In drug development, understanding plasma protein binding is crucial as it directly influences a drug’s pharmacokinetics and pharmacodynamics. Only the unbound drug in plasma remains available to elicit effects and be cleared. Hence, accurate measurement of plasma protein binding is imperative during the drug discovery phase.

The most efficient method for evaluating plasma protein binding is rapid equilibrium dialysis. This approach minimizes the impact of nonspecific binding, unlike slower methods such as ultrafiltration and HT-Dialysis, ensuring quicker attainment of equilibrium.

Sygnature Discovery’s Plasma Protein Binding assay employs the Rapid Equilibrium Dialysis (RED) device to determine the percentage binding of a test compound to plasma proteins across various species (e.g., human, rat, dog, mouse, monkey). This facilitates calculation of the percentage unbound. The process involves incubating test compounds and species-specific positive controls in 100% plasma, followed by dialysis against buffer in the RED device. This occurs over a 4-hour period at 37°C in a 5% CO2 incubator, with continuous 200 rpm shaking. Subsequently, matrix-matched samples are analysed via LC-MS/MS against a standard curve created using 100% plasma.

This optimized approach expedites plasma protein binding assessment, ensuring accurate insights into a compound’s binding characteristics across species and expediting the drug discovery process.