ABSTRACT
Chemical delivery/absorption into and through the skin is important in both dermato-pharmacology and dermato-toxicology. The human stratum corneum is the first layer of the skin and constitutes a rate-limiting barrier to the transport of most chemicals across the skin (1). Chemicals must first partition into the stratum corneum before entering the deeper layers of the skin, the epidermis, and the dermis to reach the vascular system. Chemical partitioning proceeds much faster than complete diffusion through the whole stratum corneum, and the process quickly reaches equilibrium. In addition to binding within the stratum corneum, a chemical can also be retained within the stratum corneum as a reservoir (2). Thus, understanding the process of chemical partitioning into the stratum corneum becomes important in developing an insight into its barrier properties and transport mechanisms.
