Application of Modern Drug Metabolism Structure Determination Tools and Assays to the In vitro Metabolism of Imiloxan.
ABSTRACT Imiloxan is an alpha(2) adrenoceptor antagonist and was developed for depression in the 1980's. In Phase 1 clinical trials imiloxan dosing led to hypersensitivity reactions; the molecule's development was discontinued. The present study revisits the in vitro metabolism of imiloxan using modern analytical methods. Human and rat liver microsomes convert imiloxan into a variety of metabolites many of which are unstable and or reactive. Imiloxan also yields high protein covalent binding in microsomal assays. Imiloxan is a useful test molecule for defining the relationship between liver covalent binding and idiosyncratic toxicity.
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ABSTRACT: The microsomal metabolism of ketoconazole is revisited using accurate mass LC/MS(n) and deuterium labelling. Structures for sixteen metabolites are proposed from rat and human microsomal metabolism of commercial ketoconazole. Thirteen of the proposed structures are well determined and consistent with all data; five of the proposed structures are less certain. Ten of the metabolites are described for the first time. Reaction phenotyping shows that most of the metabolites arise from CYP3A4, the enzyme known to be well inhibited by ketoconazole.Drug metabolism letters. 08/2009; 3(3):191-8.