IDENTIFICATION AND QUANTITATION OF CORTICOSTEROIDS AND THEIR ESTERS IN PHARMACEUTICAL PREPARATIONS OF CREAMS AND OINTMENTS BY THIN-LAYER CHROMATOGRAPHY AND DENSITOMETRY

A rapid, simple, and specific thin-layer chromatographic (TLC) method is described for estimation of various corticosteroids and their ester s when present in combination with other drugs in pharmaceutical prepa ration of creams and ointments. The cream or ointment is dissolved in chloroform; water and insoluble material, if any, are removed by centr ifugation, and the steroid is separated from other ingredients by TLC on silica gel G with n-hexane as the first developing solvent (to wash out cream or ointment base) and chloroform-ethyl acetate (1 + 1, v/v, for free steroids or 2 + 1, v/v, for steroid esters) as the second de veloping solvent. The separated steroid or ester is visualized under s hortwave UV (254 nm) and estimated by spectrodensitometry at 240 nm. R ecoveries of the steroids are between 98.0 and 101.7%. Results were co mpared with those obtained by official methods, where applicable, and excellent agreement was found.