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Reactive metabolites are estimated to be one of the main reasons behind unexpected drug-induced toxicity, by binding covalently to cell proteins or DNA. Due to their high reactivity and short lifespan, reactive metabolites are analyzed after chemical trapping with nucleophilic agents such as glutathione or cyanide. Recently, unexplained and uncharacterized(More)
Reactive metabolites are believed to be one of the main reasons for unexpected drug-induced toxicity issues, by forming covalent adducts with cell proteins or DNA. Due to their high reactivity and short lifespan they are not directly detected by traditional analytical methods, but are most traditionally analyzed by liquid chromatography/tandem mass(More)
In vitro methods to produce metabolic information have increasingly been applied in toxicity risk assessment. In the current contract project of JRC/ECVAM In vitro-Toxicology Unit, 55 organic chemicals, mostly drugs and pesticides, most belonging to ECVAM/ICCVAM validation compounds, expected to be analyzable by LC-MS technique, were subjected to a(More)
The so-called human xenosensors, constitutive androstane receptor (hCAR), pregnane X receptor (hPXR) and aryl hydrocarbon receptor (hAhR), participate in drug metabolism and transport as well as in several endogenous processes by regulating the expression of their target genes. While the ligand specificities for hPXR and hAhR are relatively well described,(More)
Liquid chromatography-mass spectrometry (LC-MS) with generic gradient elution for a large number of chemically different compounds is a common approach in drug development, used to acquire a large amount of data in a short time frame for drug candidates. The analysis with non-optimized parameters however may lead to a poor method performance for many(More)
Drug metabolism can result in the formation of highly reactive metabolites that are known to play a role in toxicity resulting in a significant proportion of attrition during drug development and clinical use. Thus, the earlier such reactivity was detected, the better. This review summarizes our multi-year project, together with pertinent literature, to(More)
Liquid chromatography in combination with mass spectrometry (LC/MS) is a superior analytical technique for metabolite profiling and identification studies performed in drug discovery and development laboratories. In the early phase of drug discovery the analytical approach should be both time- and cost-effective, thus providing as much data as possible with(More)
In vitro glucuronidation assays of diclofenac and indomethacin at pH 7.4 are biased by the instability of the glucuronides due to acyl migration. The extent of this acyl migration may be reduced significantly by performing the glucuronidation reaction at pH 6.0. Testing the human UDP-glucuronosyltransferases (UGTs) of subfamilies 1A, 2A and 2B at pH 7.4(More)
Cell differentiation increases UDP-glucuronosyltransferase (UGT) gene expression in Caco-2 cells. Glucuronidation of 13 UGT substrates, 1-naphthol, diclofenac, epitestosterone, estradiol, ethinylestradiol, indomethacin, oxazepam, R- and S-propranolol, propofol, testosterone, trifluoperazine, and zidovudine, were studied to derive a broad view on the effect(More)
BACKGROUND The use of high-resolution MS systems for quantitative bioanalysis is a growing field, even though a clear majority of bioanalytical methods are still based on MS/MS with triple quadrupole (QqQ) instrumentation. The recent advances in TOF-MS technology have provided increased linear range and a high selectivity of detection by increased mass(More)