In Vitro Plasma Protein Binding Assays

Apredica provides fast in vitro plasma proteing binding assay turnaround. Contact us to learn more our preclinical ADME Tox services.

A thorough understanding of plasma and tissue (brain, liver, etc.) protein binding is crucial for evaluating the distribution of drug candidates.

In vitro studies with plasma have proven to be a valuable tool for predicting in vivo protein binding.¹

Apredica measures plasma and tissue protein binding by equilibrium dialysis and ultrafiltreation.

Principle of the Assay

Human or animal plasma or tissue homogenate is incubated with the test agent. The bound and unbound test agent are separated using ultrafiltration or equilibrium dialysis, and the amount of test agent in both fractions is estimated using LC/MS or HPLC.

Plasmas and Tissues Available

Human, mouse, rat, dog, and monkey plasma are routinely available. Mouse and rat liver, brain, heart are available. Other species are available on request.

Sample Requirements

20 µL of a 10 mM DMSO solution, based on a test concentration of 100 µM.

Assay Modes

% Protein Binding: Test agent is incubated at a single concentration in duplicate in plasma or tissue homogenate. Test agent is also incubated with PBS in duplicate at the same concentration to control for nonspecific binding.

Plasma or Tissue Protein K_d: Test agent is incubated at several concentrations in order to estimate the dissociation constant.

Follow-on Studies

Specific Protein Binding: The binding to specific plasma proteins such as albumin or a₁-acid glycoprotein (AGP) is measured using either a competitive fluorescence assay.

Off-Rate Measurement: Detailed binding experiments are used to estimate the rates of binding to and dissociation from the plasma protein.

Customizationis easily possible. Contact us to learn more about how plasma protein binding studies can be used in your programs.

Footnotes

1. Wright, et al. Measurement and Analysis of Unbound Drug Concentrations. Clin Pharmacokinet 30:445 (1996)