Effects of bacterial and presystemic nitroreductase metabolism of 2-chloro-5-nitro-N-phenylbenzamide on its mutagenicity and bioavailability

► Reverse bacterial mutagenicity of GW9662 was due to its nitroreduction by bacteria. ► GW9662 had rapid clearance and large volume of distribution in i.v. dosed rats. ► Parent drug was virtually absent in plasma from orally dosed rats and dogs. ► Amine metabolite was the major species found in plasma on oral animal dosing. ► This amine metabolite was absent in plasma following animal intravenous dosing.