Pharmacokinetic Assays

In clinical studies, pharmacokinetic (PK) data are critical for determining both exposure–efficacy and exposure–safety relationships which then allow determination of the dosing window for achieving optimal efficacy with minimal safety risks. This chapter discusses the application of each methodology in PK assay development for in vivo characterization. Critical reagents, such as recombinant target proteins, anti-idiotypic antibodies, aptamers, affimers, and so on, used in the development of ligand binding assays (LBAs), immunoaffinity pulldown in liquid chromatography-mass spectrometry assays, or antigen enumeration in flow cytometry, are macromolecules with complex structure also. There are a variety of technology platforms that are commonly used for developing "fit for purpose" LBA PK methods depending on the stage of drug development. These platforms differ primarily in their detection system: colorimetric, fluorescent, chemiluminescent, or electrochemiliuminescent readouts.