RESUMO
A sensitive high-performance liquid chromatographic method has been developed for the determination of moclobemide and three of its metabolites in plasma and urine. The four substances and the internal standard were extracted from basified plasma (pH 11) with dichloromethane, with recoveries of generally more than 70%. A column packed with 5-microns Spherisorb hexyl phase and an eluent consisting of acetonitrile and aqueous phosphate buffer 30:320 (v/v) with a pH of 3.9 were found most suitable for the chromatographic separation of the four compounds of interest. Non-ideal interactions of the basic compounds and the N-oxide metabolite occurred with many other reversed-phase materials, as indicated by broad and tailing peaks. Limits of quantitation for moclobemide and its three metabolites in the range 20-30 ng/ml and a good intra-assay reproducibility ranging between 2 and 5% for concentrations over 100 ng/ml could be achieved for plasma, which increased to ca. 8-10% at a concentration of 50 ng/ml.
Assuntos
Benzamidas/análise , Cromatografia Líquida de Alta Pressão/métodos , Inibidores da Monoaminoxidase/análise , Soluções Tampão , Calibragem , Humanos , Concentração de Íons de Hidrogênio , MoclobemidaRESUMO
A high-performance liquid chromatographic method for the determination of bromazepam in plasma and of its main metabolites in urine is described. The unchanged drug is extracted from plasma with dichloromethane, using Extrelut 1 extraction tubes. The residue from this extract is subsequently analysed by reversed-phase high-performance liquid chromatography with ultraviolet detection (230 nm). The limit of detection is 6 ng/ml of plasma, using a 1-ml specimen. For the determination of the metabolites, the urine samples are incubated to effect enzymatic deconjugation and are then extracted with dichloromethane. Following two clean-up steps (back extractions), the final residue is analysed on the same reversed-phase system as the plasma samples. The limit of detection for the two metabolites is 200 ng/ml.