RESUMEN
A high-throughput and sensitive bioanalytical method using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) has been developed for the estimation of sibutramine and its two metabolites (M1 and M2). The extraction of sibutramine, its metabolites and imipramine (internal standard (IS)) from the plasma involved treatment with phosphoric acid followed by solid-phase extraction (SPE) using a hydrophilic-lipophilic balanced HLB cartridge. The SPE eluate without drying and reconstitution was analyzed by LC/MS/MS, equipped with a with turbo ion spray (TIS) source, operating in the positive and multiple reaction monitoring (MRM) acquisition mode. Sample preparation by this method yielded extremely clean extracts with quantitative and consistent mean recoveries; 95.12% for sibutramine, 92.74% for M1, 95.97% for M2 and 96.60% for the IS. The total chromatographic run time was 3.0 min with retention times of 2.51, 2.13, 2.09 min for sibutramine, M1, M2 and imipramine, respectively. The developed method was validated in human plasma matrix, with a sensitivity of 0.1 ng/mL (coefficient of variance (CV), 2.07%) for sibutramine, 0.1 ng/mL (CV, 3.59%) for M1 and 0.2 ng/mL (CV, 4.93%) for M2. Validation of the method for its accuracy, precision, recovery, matrix effect and stability was carried out especially with regard to real subject sample analysis. The response was linear over the dynamic range 0.1 to 8.0 ng/mL for sibutramine and M1, and 0.2 to 16.0 ng/mL for M2 with correlation coefficients of r > or = 0.9959 (sibutramine), 0.9935 (M1) and 0.9943 (M2). The method was successfully applied for bioequivalence studies in 40 human subjects with 15 mg capsule formulations.
Asunto(s)
Aminas/sangre , Aminas/farmacocinética , Análisis Químico de la Sangre/métodos , Cromatografía Liquida/métodos , Ciclobutanos/sangre , Ciclobutanos/farmacocinética , Espectrometría de Masa por Ionización de Electrospray/métodos , Humanos , Equivalencia TerapéuticaRESUMEN
A rapid and sensitive liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method for the determination of isosorbide-5-mononitrate (5-ISMN), used in the treatment of angina pectoris, in human plasma is described. The quantification of 5-ISMN was performed via stable acetate adduct formation with a high relative abundance. The plasma filtrate obtained after solid-phase extraction (SPE), using a polymer based, hydrophilic-lipophilic balanced (HLB) cartridge, was submitted directly to reversed-phase high-performance liquid chromatography separation followed by ESI and detection of the resulting ions using triple-quadrupole mass spectrometry in selected reaction monitoring (SRM) mode. There was no significant matrix effect on the analysis. For validation of the method, the recovery of the free analyte response was compared to that obtained from an optimized extraction method. The analyte stability was examined under conditions mimicking the sample storage, handling, and analytical procedures. The extraction procedure yielded extremely clean extracts with a recovery of 95.51% and 93.98% for iossorbide-5-mononitrate and topiramate (internal standard (IS)), respectively. The calibration curves were linear for the dynamic range of 10.0 to 1000.0 ng/mL with a correlation coefficient r > or = 0.9985. The intra-assay and inter-assay precision for the samples at the lower limit of quantification (LLOQ) were 9.02 and 13.30%, respectively. The intra-assay accuracies at LLOQ, LQC, MQC and HQC levels varied from 98.13 to 118.15, 102.34 to 105.21, 100.69 to 109.68, and 95.76 to 102.92%, respectively, while the inter-assay accuracies ranged from 93.10 to 118.15, 93.03 to 107.04, 86.97 to 109.68 and 86.18 to 105.85%, respectively, at these levels. The method is rugged and fast with a total run time of 2 min. The method was successfully applied for a bioequivalence study in 24 human subject samples after oral administration of 60 mg extended release (ER) formulations.