Optimisation of a Selective Liquid Chromatography Procedure for Hydrocortisone Acetate, Hydrocortisone Alcohol and Preservatives in a Pharmaceutical Emulsion

An accurate, reproducible and specific stability-indicating method for the high performance liquid chromatography (HPLC) assay of hydrocortisone acetate, hydrocortisone alcohol, methyl p-hydroxybenzoate and propyl p-hydroxybenzoate in a pharmaceutical suspension is described. An investigation of several column phases was undertaken and a Zorbax SB-Phenyl column gave the best selectivity and specificity due to the π-π interactions between the analytes and stationary phase. All the components were fully resolved in less than 15 min under isocratic conditions using UV detection at 254 nm with a water-methanol mobile phase. The stability-indicating method was validated over the linearity range of 25% to 150% of the nominal concentrations of each analyte. Nominal concentrations were hydrocortisone acetate (10% w/w), hydrocortisone alcohol (0.2% w/w with respect to hydrocortisone acetate), methyl p-hydroxybenzoate (0.1% w/w) and propyl p-hydroxybenzoate (0.01% w/w) respectively.