Radiolabeled Metabolite Identification

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Radiolabeled Metabolite Identification

Study Purpose

Radioisotope tracing technology combined with an LC-HRMS analysis platform can be used to quantify and identify in vitro radio-labeled metabolites (animal and human), helping determine in vitro metabolic pathways.

Radiolabeled absorption, distribution, metabolism, and excretion (ADME) of candidate compounds in animal and human can be performed using radioactivity analysis together with LC-HRMS. These studies can determine mass balance and extraction and metabolite profiles and structures in plasma, urine, feces, and/or bile, and drug clearance pathways in in vivo metabolite profiles. The combination of mass balance, excretion routes, metabolite profiles and identification, a major metabolic pathway, and the clearance pathway of a drug in animal and human can be accurately determined. These results can further guide the follow-up studies, such as metabolizing enzyme phenotyping and/or transporter substrate analysis, clinical DDI experiments, and special population experiments (hepatic or renal impairment, gene polymorphism).

Platform Introduction

WuXi AppTec DMPK can provide radio-labeled MetID of [14C] and [3H] labeled compounds in vitro, in animal and human. Experimental models include but are not limited to metabolic stability and metabolite identification studies in vitro (plasma, liver S9, liver microsomes, or hepatocytes from multiple species) and in vivo (mice, rats, dogs, monkeys, and human). The radiolabeled metabolite identification platform has been applied to various compound types, including conventional small molecules, high-polar and non-polar small molecules, natural products, nucleotides, Proteolysis-Targeting Chimeras(PROTACs), peptides, ADCs, PDCs, and oligonucleotide. Matrix types include blood, plasma, urine, feces, bile, tissues.

Feature Introduction

Radioisotope tracer technology has unique advantages in MetID studies. Based on radioactive metabolite profiles, the distribution of each metabolite can be clearly and accurately observed. Apart from searching for metabolites, [14C] isotopes can also help the identification of metabolites. Mass spectrometry or UV detection may differ between MS/UV response and the actual amount of metabolites due to their ionization efficiency or UV absorption. The radioactivity determination can intuitively and accurately quantify and characterize metabolites (see the figure ).

Representative Radiolabeled Assays

Representative Radiolabeled Assays
1. Eugenia Kraynov et al., Current Approaches for Absorption, Distribution, Metabolism, and Excretion Characterization of Antibody-Drug Conjugates: An Industry White Paper, Drug Metabolism and Disposition, 44: 617-623, May 2016
2. U.S. Department of Health and Human Services Food and Drug Administration Center for Drug Evaluation and Research (CDER), Safety Testing of Drug Metabolites Guidance for Industry, Pharmacology/Toxicology, March 2020, Revision 2
3. Cornelis E. C. A. Hop, et al., Plasma-Pooling Methods to Increase Throughput for in Vivo Pharmacokinetic Screening, Journal of Pharmaceutical Sciences, Vol. 87, No. 7, July 1998
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