In Vitro Drug Metabolism Studies Using Human Liver Microsomes

Abstract

Metabolism of most pharmaceutical drugs occurs in the liver. In drug metabolism, enzymes convert drugs to highly water-soluble metabolites to facilitate excretion from the body. Thus, in vitro models for studying drug metabolism usually target hepatocytes or subcellular liver fractions like microsomes, cytosols, or S9 fractions with high concentrations of specific enzymes. The most popular subcellular fraction used during drug discovery tends to be the microsomes, as these are easy to prepare and store, are amenable to high throughput screening, and are a relatively low-cost option. Understanding the metabolic stability and kinetics of glucuronidation of an investigational drug is crucial for predicting the pharmacokinetic parameters that support dosing and dose frequency. This chapter provides detailed information about metabolite profiling, metabolic stability, glucuronidation kinetics, reactive metabolites identification, CYP enzyme inhibition, and general protocols using human liver microsomes.

Real-time fluorescent monitoring of phase I xenobiotic-metabolizing enzymes

“…9,14 Phase I enzymes have garnered attention in the development of enzyme-directed uorescence chemosensors, owing to their inclusion of pharmacologically signicant enzymes such as esterase, cytochrome P450 family, monoamine oxidase, nitroreductase, aldehyde dehydrogenase, and glycosidase. 10,15 These enzymes actively participate in the metabolism and activation of numerous prodrugs, with their overexpression in cancer cells marking them as potential biomarkers for early-stage cancer diagnosis and monitoring therapeutic efficacy of cancer drugs. [16][17][18][19] Anticipating a surge in cancer cases, the World Health Organization predicts 24 million new cases and 14.4 million annual deaths by 2035.…”

Electrochemical Simulation of Phase I Hepatic Metabolism of Voriconazole Using a Screen-Printed Iron(II) Phthalocyanine Electrode

“…HLMs are derived from the liver's endoplasmic reticulum through differential high-speed centrifugation. This technique allows for the isolation of the subcellular fractions that contain important enzymes involved in hepatic drug metabolism, including cytochrome P450s and UGTs (UDP-glucuronosyltransferases) [9].…”