Chapter 5 In vitro dmpk screening in drug discovery, role of lc-ms/ms

Abstract

The goal of drug discovery programs is to identify new chemical entities (NCEs) suitable for development as therapeutic agents. Recent advances in chemical synthesis, structural chemistry, molecular biology, and robotics have greatly increased the number of compounds requiring evaluation; therefore, increasing the demands for drug metabolism and pharmacokinetics (DMPK) screening. This is particularly true in the early stage of drug discovery, where a large number of NCEs needs to be evaluated so that the selected few can proceed to drug development. In vitro models for the assessment of the biopharmaceutical properties such as metabolic stability, permeability across the human colon carcinoma cell line (Caco-2) and inhibition of cytochrome P450 isoforms (CYPs), are faster, easier to perform and require less amount of compound; therefore, amendable to higher-throughput screening. Performance of many of these in vitro screens in a higher-throughput format has been made possible primarily by the availability of liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). This chapter discusses two primary human-based in vitro screening systems, namely— the CYP enzyme inhibition and Caco-2 permeability, along with a secondary screen, the blood-brain-barrier (BBB) penetration model. The role of LC-MS/MS in making these assays possible in drug discovery is emphasized.