The Fate of Liposomes in Animal Skin

Abstract: Introduction The skin performs a significant protective role in the human body. The epidermis is the primary and most effective barrier to the percutaneous absorption of chemicals. This function depends on the protective horny layer the stratum corneum [5]. The epidermis produces special compounds such as lipids amino acids and salts to build the membrane in the lower stratum corneum. These compounds released by lysis of epidermal cells and organelles constitute the barrier function of the stratum corneum conjunctum [6]. The rate of the diffusion through the stratum corneum is for most chemicals very low. Moreover some chemicals interact with the epidermal tissue in the course of percutaneous penetration. The barrier capacity of the skin tissue beyond that of the stratum corneum has been considered to be minimal. However accumulating reports indicate that the underlying skin jayers including the dermis are far form being completely permeable to penetrants [4]. The retention of chemicals in any of the cutaneous tissues is a net outcome of the reversible affinity binding and partitioning of substances between aqueous vehicles and tissue components [7]. Traditionally the key to topical delivery of drugs has been to a great extent the ability to alter this barrier function of the skin. For example dimethyl sulphoxide and soaps can increase the cutaneous penetration of chemicals [3]. The recognition of the advantages of using skin as the port of entry for drugs is becoming a major impetus for discovering materials that increase skin penetration. It is expected that new technologies will not destroy the main barrier function of the stratum corneum. A significant step in the development of such a technology has involved recent investigations on liposomes [8-13]. Our study was designed to obtain accurate quantitative data on the comparative absorption of different concentrations of liposomes and their partitioning in different skin tissues. hl

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