Plasma Protein Binding Assay (Equilibrium Dialysis)

Background: The vast majority of small molecule drugs are reversibly bound to blood plasma proteins (albumin, lipoproteins, α1-acid-glycoprotein) soon after the administration. The bound drug molecules fraction is generally considered not available for interaction with their biological targets. Determining the extent of drug-protein binding is among key stages in drug development as it influences compound efficacy, dosing, clearance rate, and potential for drug interactions. Rapid Equilibrium Dialysis (RED) is the “golden standard” method to determine the percentage of the plasma protein binding (%PPB) for a drug candidate.

Deliverable: The percentage of plasma protein-bound compound is calculated based on the LC-MS measurements of the compound concentrations in plasma and buffer solutions. Full study report is provided.

Sample Submission: A minimal accurately weighable quantity of dry compound (~1 mg or 2 µmol) or 50 µL of 10-20 mM stock DMSO solution is required for this assay. For multiple assays, lesser amount of compound per assay may be sufficient, depending on the particular project. We do not need to know structures of the molecules for ADME testing. However, brutto formulas have to be provided for all studies involving MS detection.