Determination of circulating ethyl loflazepate metabolites in the baboon by radio-high-performance liquid chromatography with injection of crude plasma samples: comparison with solvent extraction and thin-layer chromatography.

Circulating ethyl loflazepate metabolites in the baboon were determined, following a single oral administration of the 14C-labelled drug, by radio-high-performance liquid chromatography with injection of crude plasma samples and by selective extraction with thin-layer chromatographic analysis of the radioactive components. Metabolites identified by comparing their chromatographic behaviour with synthetic standards were loflazepate, descarboxyloflazepate and 3-hydroxydescarboxyloflazepate. Loflazepate represented about 70% of the circulating radioactivity; the two other metabolites were present in amounts too small to allow accurate quantification. The parent drug was not present in the blood. Comparison of high-performance liquid chromatography with solvent extraction demonstrated the inaccuracy of the latter to be caused by the conversion of loflazepate to descarboxyloflazepate.