Oil-water-oil multiple emulsions for prolonged delivery of hydrocortisone after topical application: comparison with simple emulsions

Multiple emulsions show a high potential for prolonged delivery of drugs. In multiple emulsions, the entrapped substance can be transfered from the internal phase to the external phase through the middle phase, i.e. the membrane phase. These systems could be used for prolonged delivery of drugs. The present study was aimed to assess the suitability of oil-water-oil emulsions as prolonged release topical formulations of hydrocortisone. In order to avoid any influence of the composition of the formulation and to study only the effect of the emulsion type, a multiple emulsion as well as a simple emulsion were prepared with exactly the same composition. The percutaneous absorption of hydrocortisone from these two emulsion types was studied. At a finite dose, the percentage of hydrocortisone absorbed from the simple emulsion was 1.5-fold greater than that observed from the multiple emulsion, and the drug was kept longer in the epidermis and dermis from this galenic form. It was concluded that the multiple oil-water-oil emulsion systems may be used for obtaining a prolonged topical release of hydrocortisone. (C) 1998 Elsevier Science B.V.