on 05-01-201210:31 AM - edited on 10-15-202111:29 AM by Closed Account
Huang Y, Herbold R, Stratton T, Sharma S. Application Note 504 Current approaches to discovery stage drug metabolism studies, such as pharmacokinetics and hepatocyte stability, have focused on the use of targeted analysis-based approaches like multiple reaction monitoring (MRM) for quantitative analysis. This necessitates the optimization of parameters such as Q1 and Q3 m/z values, collision energy, and interface voltages. These studies detect only the specified compound; information about other components, such as metabolites, is lost. The ability to do full scan acquisition for quantitation eliminates the need for compound optimization, while enabling the detection of metabolites and other non-drug related endogenous components. Samples from a tolbutamide in vitro rat hepatocyte incubation were analyzed using the Thermo Scientific Exactive benchtop liquid chromatography-Orbitrap mass spectrometry system to demonstrate its capability to produce high resolution, full scan MS and Higher Energy Collision Cell Dissociation (HCD) data. This data can be used for qualitative and quantitative assessment of compounds in early drug discovery studies. From the same data set, HCD can be used for structural elucidation as well as to obtain quantitative data to generate plots for the disappearance of the parent and the appearance of metabolites. Tolbutamide is metabolized almost exclusively along a single pathway. Methyl hydroxylation to form hydroxytolbutamide is the initial and rate limiting step. Subsequent oxidation of hydroxytolbutamide by alcohol and aldehyde dehydrogenases results in carboxytolbutamide.