Yasuji Takashima

Studies on drug release from ointments. V: Release of hydrocortisone butyrate propionate from topical dosage forms to silicone rubber

Abstract The release of hydrocortisone butyrate propionate (HBP) from oil-in-water (o/w) cream and aqueous gels containing propylene glycol and ethanol to silicone rubber as a model for the skin was investigated. The release of HBP from o/w cream or gels was carried out under open or closed conditions at 35°C and 75% RH. The influence of the evaporation of vehicle components of the cream or gels on the release of HBP was examined. The release of HBP from o/w cream and aqueous gel containing propylene glycol under open conditions was lower than that under closed conditions, while the release of HBP from aqueous gel containing ethanol in open conditions was markedly higher than that under closed conditions. These differences in the release of HBP between open and closed conditions were related to changes in the thermodynamic activity of HBP in the vehicle during the release period. The results of HBP release under open conditions were nearly correlated with those of in vivo vasoconstrictor activity. The release method using silicone rubber under open conditions is considered to be useful for the evaluation of topical dosage forms, particularly those containing volatile components.