Abstract
The aim of this study was to develop and validate a LC stability-indicating method for the quantitation of desonide hair lotion currently marketed in Brazil, as well as delineate upon the photostability study of the same pharmaceutical product. The method used a RP-18 column (150 x 4.6 mm, 5 mm), with a methanol-acetonitrile-triethylamine solution as mobile phase (0.3 %, pH 4.0) (50:10:40, v/v/v) and UV detection at 244 nm. The method satisfied all the validation requirements, evidenced by good linearity (r > 0.9999, in the range from 5 to 100 μg mL-1), accuracy (recovery average 100.26%), precision (intraday RSD 0.45 and 1.76%; interday RSD 1.23%), robustness and specificity, indicated by good resolution between the analite peak from adjacent peaks (R>2.0) and suitable peak purity index in all the stress conditions. In order to evaluate the photostability of desonide hair lotion and desonide active pharmaceutical ingredient (desonide API), their portions were exposed to UVA light. The degradation of desonide hair lotion 0.1% in the conditions tested can be described by first-order kinetics, with the residual desonide content being around 39% after 15h exposure. The content of desonide API was 96.5%, after 72h exposure. The results indicate the instability of desonide in the evaluated drug product. Considering the characteristics of the developed method, it can be applied in the quality control routine of desonide in hair lotion and in stability studies.
Keywords: Desonide, desonide assay, desonide hair lotion, desonide photostability, desonide stability, validation.
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