ABSTRACT
I. INTRODUCTION Ointments and creams have been used for many centuries to improve the healing conditions of wounds and to treat in empirical ways skin diseases as well as to retard the aging process of the skin and to preserve natural beauty. Dermatological preparations and cosmetics that represent the modern generations of these systems are also called semisolids due to their unique properties of being in the solid state under ambient conditions and being transformed to the liquid state when mechanically stressed during the application on the skin. These properties allow the systems to spread easily on the surface of the skin. Depending on the formulation, ointments in general remain on the surface of the skin and show skin protection and occlusion, whereas creams may be able to penetrate into the different layers of the skin, especially the stratum corneum (horny layer) and to exert interactions with both the keratines in the horny cells (corneocytes) and the lipid bilayers in which the horny cells are embedded.
