Rapid blue tetrazolium procedure for analysis of corticosteroids in pharmaceutical preparations

A rapid quantitative analysis of nine selected corticosteroids and corticosteroid esters at room temperature is described. The procedure is similar to the official blue tetrazolium reaction for corticosteroids, except that methylene chloride instead of alcohol USP is used as a solvent and the reagents are dissolved in or diluted with nonaqueous solvents. These two modifications reduce the medium polarity, which increases the reaction rate. The reactions are complete in 7-18 min, and the formazans are stable for at least 90 min. The results from 15 different pharmaceutical formulations, 12 containing hydrocortisone and three containing prednisolone acetate, show that the proposed method gives results that compare favorably with those obtained by the official blue tetrazolium, isoniazid, and phenylhydrazine procedures.