In vitrometabolism of a triclyclic alkaloid (M445526) in human liver microsomes and hepatocytes

Drug metabolism in silico - the knowledge-based expert system approach. Historical perspectives and current strategies

Drug metabolism in silico is briefly discussed in terms of the importance of understanding the mechanistic basis of drug molecule biotransformation in vivo and its consequences in terms of changes in the properties of metabolites relative to those of the parent compound. A basic overview of an expert system is presented, along with how these general principles apply to expert systems for the prediction of xenobiotic metabolism. A brief history of the development of these systems is also presented. Methods for increasing both the sensitivity and selectivity of prediction are outlined and the benefits of using complementary prediction systems in a conjoint manner are proposed.

Nuclear magnetic resonance (NMR)-based drug metabolite profiling

The identification of drug metabolites in biofluids such as urine, plasma and bile is an important step in drug discovery and development. Proton nuclear magnetic resonance ((1)H-NMR) spectroscopy can provide detailed information regarding the structural transformation of a compound as a consequence of metabolism. However, successful identification of drug metabolites by (1)H-NMR spectroscopy is generally compromised by the presence of endogenous metabolites, which can obscure the signals of the drug metabolites in question. Hence, sample clean-up and separation of the metabolites from the biofluid matrix is crucial. This is generally achieved by extraction of the biofluid, solid-phase extraction (SPE), high-performance liquid chromatography (HPLC) or any combination of these. Apart from (1)H, other NMR-active nuclei, such as (19)F, can provide a useful handle for metabolite profiling, provided they are not naturally present in the biofluid. Successful studies have shown that the presence of a fluorine-handle on the drug and its metabolites can provide additional qualitative and quantitative data by (19)F-NMR spectroscopy. This chapter provides guidelines and examples of NMR-based drug metabolite profiling.