RESUMO
AIM: Dexamethasone (Dex) has been used for the treatment of ocular diseases, presenting concentrations up to 150 ng/ml in the biological matrix. Drug sampling has been performed from aqueous humor (AH), which the volume varies from 50 to 200 µl, becoming a challenge for analytical analyses. RESULTS: We developed and validated a direct and sensitive method by LC-MS/MS for Dex measurement in human AH, using water as surrogate matrix to reduce the sample volume applied in some validation assays. With accuracies of 99.6% and precision within 15% in the range of 0.1-150 ng/ml, Dex had an 87-day stability. CONCLUSION: Our method is robust and sensitive enough to be applied in bioequivalence studies with human AH using only 20 µl of biological sample.
Assuntos
Humor Aquoso/química , Testes de Química Clínica/métodos , Dexametasona/análise , Cromatografia Líquida , Dexametasona/farmacocinética , Humanos , Espectrometria de Massas em Tandem , Equivalência TerapêuticaRESUMO
17ß-Estradiol (E2) is an endogenous steroid in the human body. Its measurement is important for health and human biology understanding. However, E2 concentration in human plasma is in the range of pg/mL, which makes it difficult to detect. In this way, LC-MS/MS has been shown the most sensitive tool, although E2 is a weakly ionizable molecule. In this work, we validated a more sensitive and accurate method for E2 quantification in human plasma. Our extraction step ensured a cleaner chromatography, resulting in a precise measurement and highly reproducible method in the range of 2-150pg/mL. Moreover, we proved a long stability for E2 in several conditions. All results indicate that our developed method is robust and sensitive enough to apply in bioequivalence studies for E2 measurement in human plasma, even at very low concentrations.
