{"title":"Partial protein binding of uracil and thymine affects accurate dihydropyrimidine dehydrogenase (DPD) phenotyping","authors":"","doi":"10.1016/j.jpba.2024.116381","DOIUrl":null,"url":null,"abstract":"<div><p>Fluorouracil is among the most used antimetabolite drugs for the chemotherapeutic treatment of various types of gastrointestinal malignancies. Dihydropyrimidine dehydrogenase (<em>DPYD</em>) genotyping prior to fluorouracil treatment is considered standard practice in most European countries. Yet, current pre-therapeutic <em>DPYD</em> genotyping procedures do not identify all dihydropyrimidine dehydrogenase (DPD)-deficient patients. Alternatively, DPD activity can be estimated by determining the DPD phenotype by quantification of plasma concentrations of the endogenous uracil and thymine concentrations and their respective metabolites dihydrouracil (DHU) and dihydrothymine (DHT). Liquid chromatography - mass spectrometry (LC-MS) detection is currently considered as the most adequate method for quantification of low-molecular weight molecules, although the sample preparation method is highly critical for analytical outcome. It was hypothesized that during protein precipitation, the recovery of the molecule of interest highly depends on the choice of precipitation agent and the extent of protein binding in plasma. In this work, the effect of protein precipitation using acetonitrile (ACN) compared to strong acid perchloric acid (PCA) on the recovery of uracil, thymine, DHU and DHT is demonstrated. Upon the analysis of plasma samples, PCA precipitation showed higher concentrations of uracil and thymine as compared to ACN precipitation. Using ultrafiltration, it was shown that uracil and thymine are significantly (60–65 %) bound to proteins compared to DHU and DHT. This shows that before harmonized cut-off levels of DPD phenotyping can be applied in clinical practice, the analytical methodology requires extensive further optimization.</p></div>","PeriodicalId":16685,"journal":{"name":"Journal of pharmaceutical and biomedical analysis","volume":null,"pages":null},"PeriodicalIF":3.1000,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of pharmaceutical and biomedical analysis","FirstCategoryId":"3","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0731708524004217","RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, ANALYTICAL","Score":null,"Total":0}
引用次数: 0
Abstract
Fluorouracil is among the most used antimetabolite drugs for the chemotherapeutic treatment of various types of gastrointestinal malignancies. Dihydropyrimidine dehydrogenase (DPYD) genotyping prior to fluorouracil treatment is considered standard practice in most European countries. Yet, current pre-therapeutic DPYD genotyping procedures do not identify all dihydropyrimidine dehydrogenase (DPD)-deficient patients. Alternatively, DPD activity can be estimated by determining the DPD phenotype by quantification of plasma concentrations of the endogenous uracil and thymine concentrations and their respective metabolites dihydrouracil (DHU) and dihydrothymine (DHT). Liquid chromatography - mass spectrometry (LC-MS) detection is currently considered as the most adequate method for quantification of low-molecular weight molecules, although the sample preparation method is highly critical for analytical outcome. It was hypothesized that during protein precipitation, the recovery of the molecule of interest highly depends on the choice of precipitation agent and the extent of protein binding in plasma. In this work, the effect of protein precipitation using acetonitrile (ACN) compared to strong acid perchloric acid (PCA) on the recovery of uracil, thymine, DHU and DHT is demonstrated. Upon the analysis of plasma samples, PCA precipitation showed higher concentrations of uracil and thymine as compared to ACN precipitation. Using ultrafiltration, it was shown that uracil and thymine are significantly (60–65 %) bound to proteins compared to DHU and DHT. This shows that before harmonized cut-off levels of DPD phenotyping can be applied in clinical practice, the analytical methodology requires extensive further optimization.
期刊介绍:
This journal is an international medium directed towards the needs of academic, clinical, government and industrial analysis by publishing original research reports and critical reviews on pharmaceutical and biomedical analysis. It covers the interdisciplinary aspects of analysis in the pharmaceutical, biomedical and clinical sciences, including developments in analytical methodology, instrumentation, computation and interpretation. Submissions on novel applications focusing on drug purity and stability studies, pharmacokinetics, therapeutic monitoring, metabolic profiling; drug-related aspects of analytical biochemistry and forensic toxicology; quality assurance in the pharmaceutical industry are also welcome.
Studies from areas of well established and poorly selective methods, such as UV-VIS spectrophotometry (including derivative and multi-wavelength measurements), basic electroanalytical (potentiometric, polarographic and voltammetric) methods, fluorimetry, flow-injection analysis, etc. are accepted for publication in exceptional cases only, if a unique and substantial advantage over presently known systems is demonstrated. The same applies to the assay of simple drug formulations by any kind of methods and the determination of drugs in biological samples based merely on spiked samples. Drug purity/stability studies should contain information on the structure elucidation of the impurities/degradants.