Effect of water content and type of emulgator on the release of hydrocortisone from o/w creams.

The release of hydrocortisone was determined in vitro from o/w-creams containing an anionic (sodium lauryl sulphate), a cationic (cetrimide) or a nonionic (cetomacrogol 1000) surfactant as emulgator and different amounts of water. The solubility of hydrocortisone in water-emulgator systems and the solubilizing capacity of these emulgators for hydrocortisone were also determined. The release of hydrocortisone from creams containing emulgators increased in the same order as the solubilizing capacity of these emulgators for hydrocortisone, which indicates how important the concentration of dissolved hydrocortisone in the cream is for release. The effect of water content on the release of hydrocortisone was also dependent on the emulgator used. With a nonionic emulgator, release was enhanced slightly as the water content in the cream increased. In the case of ionic emulgators, release of hydrocortisone was retarded as the amounts of water in the cream increased up to 60% water content; above this, the release was enhanced, probably owing to changes in the liquid crystalline microstructure of the cream.