High-performance liquid chromatographic assay of betamethasone 17-valerate and its degradation products.

A high-performance liquid chromatographic assay of betamethasone 17-valerate is described. The procedure may be use for quantitative assay of the degradation products, betamethasone 21-valerate and betamethasone, and the application to the analysis of ointments is described. The method is also suitable for the determination of the kinetics of decomposition from one experimental run, and the determination of rate constants from a four-compartment sequential reaction is described. The procedure is also applicable to other corticosteroids, and hydrocortisone 17-butyrate, hydrocortisone 21-butyrate, and hydrocortisone may similarly be determined without modification to the method.