Protective and retentive effects of liposomes on water-degradable hydrocortisone acetate in dermatological applications

Various dermatological samples containing liposomes as a drug carrier were prepared, and the effects of variations in the dermatological formulations, such as liposomal encapsulation, base materials, and the purity of lipid p roducts, on drug stability and characteristics for effective topical drug d elivery were investigated. Hydrocortisone-21-acetate, a hydrophobic and wat er-degradable, anti-inflammatory agent, was used as the model drug. It was found that the liposomally encapsulated drug was more stable than the free- form drug in an ointment formulation. Also, the hydrogel base was found to be effective in maintaining drug stability in spite of its high water conte nt. Another evidence that liposomes were surrounding drug particles in the base was obtained from an in vitro test of drug permeation from liposome-hy drogel through the pig ear skin. The permeability of hydrocortisone acetate through the skin membrane was found to be 2.7-fold lower in the case of li posome-hydrogel than in the case of free-drug hydrogel. The results also su ggested that liposomes play a role in localizing drug molecules in the skin membrane.