RESUMO
A new spectrofluorimetric method for the determination of omeprazole (OMP) based on its degradation reaction catalyzed by ultraviolet (UV) light is proposed. OMP in aqueous solution is very unstable, which renders a serious difficulty for controlling its quality. It does not show native fluorescence, but when exposed to UV radiation, it generates a highly fluorescent degradation product with adequate stability for indirect OMP quantification. Under the studied optimal experimental conditions (pH, temperature, exposure time to UV radiation), a specific rate constant of 2.851 min⻹--described by zero-order kinetic--was obtained for the degradation reaction. Using λ(exc) 293 nm and λ(em) 317 nm, a linear relationship was obtained (r² 0.9998) in the concentration range of 0.1 to 1.3 µg mL⻹, with a detection limit of 1.07 10⻳ µg mL⻹ (S/N = 3). The methodology developed was successfully applied to OMP quality control in pure drugs and tablet dosage forms without previous treatment, with good tolerance to common excipient, and a high level of concordance between the nominal and experimental values. This work constitutes an important contribution to knowledge of the degradation mechanism of OMP. It has been shown to be appropriate for OMP quality control, to have an adequate sampling rate, low cost instrument, and to be a less polluting procedure.
Assuntos
Omeprazol/análise , Inibidores da Bomba de Prótons/análise , Espectrometria de Fluorescência , Calibragem , Estabilidade de Medicamentos , Concentração de Íons de Hidrogênio , Cinética , Modelos Moleculares , Estrutura Molecular , Omeprazol/química , Omeprazol/efeitos da radiação , Omeprazol/normas , Fotólise , Inibidores da Bomba de Prótons/química , Inibidores da Bomba de Prótons/efeitos da radiação , Inibidores da Bomba de Prótons/normas , Controle de Qualidade , Reprodutibilidade dos Testes , Espectrometria de Fluorescência/normas , Comprimidos , Temperatura , Raios UltravioletaRESUMO
To guarantee that an analytical procedure gives reliable, exact and interpretable information about a sample, it must be validated. Two ambiguous parameters are detection limit and quantification limit. The determination of these limits is still of great concern and there are still a variety of procedures described in the current literature. The fundamental objective of the present work is to apply the different recommendations suggested by official guidelines for the quantitative determination of omeprazole and its impurities (omeprazole sulphone and 5-hydroxy-omeprazole) in capsules and tablets using high performance liquid chromatography with UV detection. The importance of calibration linearity in the context of the quantification limit is considered, since one of the approaches, the estimated concentrations of this limit, are deduced from the regression line. The values of the detection limit and the quantification limit obtained show that, in chromatographic analyses, the best method is that based on the use of the parameters obtained from the analytical curve, which are statistically reliable. It was shown that smaller values of the detection limit and the quantification limit were obtained by the visual approach and by the method using the signal-to-noise ratio. However, these values may reflect a subjective evaluation, prone to error and large variations. This was confirmed by showing that these methods result in values that fall outside the linear range of the method.
Assuntos
Contaminação de Medicamentos , Omeprazol/análise , 2-Piridinilmetilsulfinilbenzimidazóis/análise , Cromatografia Líquida de Alta Pressão , Omeprazol/análogos & derivados , Omeprazol/normas , IncertezaRESUMO
This report describes results of an in vitro study in which capsules containing omeprazole in enteric-coated pellets from different Brazilian manufacturers were evaluated. The original product was the reference in comparison to three similar products (A, B, and C). Samples were submitted to severe conditions (40 degrees C and 75% relative humidity during 120 days), and the tests performed were the omeprazole content, the percentage of omeprazole dissolved from the pellets, and the amount of H 238/85, its main degradation product. The data obtained suggest that these products could not be considered interchangeable. Differences in physical and physicochemical properties of products A, B, and C indicated that they did not maintain the required stability and that bioavailability might be affected by the poor dissolution of omeprazole from the pellets.