RESUMEN
An ultra high performance liquid chromatographic method has been developed and validated for the determination of betamethasone valerate (BMV) in topical dermatologic formulations. For the development of the method, response surface methodology based on a three-level full factorial design was used. The eluent composition, the column dimension and the flow rate were chosen as relevant experimental parameters to investigate. The response surface plots revealed an optimum separation by using a RP column (30 mm × 2 mm i.d., 2.2 µm particle size), at 30 °C; isocratic mobile phase consisting of acetonitrile:water (60:40) at a flow rate of 0.2 mL min(-1) and a wavelength set at 254 nm. The proposed method was validated for four types of matrices according to ICH guidelines requirements. Dexamethasone acetate (DMA) was used as internal standard. Linearity was studied in the range of 5-200 µg mL(-1) for BMV in spiked matrix samples. Recoveries were in the range of 95-105% and precision was better than 5% for both analytes, either in cream, gel, ointment, or lotion formulations, when using simple sample preparation. Retention times were 0.95 min for DMA and 1.40 min for BMV, demonstrating a short method run time. The method was successfully applied for routine analysis of dermatological formulations containing betamethasone valerate.
