Determination of bufuralol and its major metabolites in plasma by high-performance liquid chromatography

A high-performance liquid chromatographic method for the determination of bufuralol, a benzofuran analogue, in plasma is described. The unchanged drug, the major metabolites and an internal standard are extracted from plasma, purified by back-extraction steps and thereafter separated using a reversed-phase liquid chromatographic system. The detection is carried out by means of a fluorescence detector and an UV detector connected in series. The sensitivity of the assay for the unchanged drug and the major metabolite is about 1 ng/ml plasma using a 0.5 ml specimen per analysis and the relative standard deviation of the whole assay lies in the range +/- 4-5%. The procedure was successfully used to determine plasma levels in volunteers following a single oral dose of 40 mg of bufuralol. The results obtained using the new high-performance liquid chromatographic method were compared with those determined by another method which combines gas chromatography with mass fragmentography, and it was found that these two sets of results coincided quite well.