ABSTRACT
Chemical delivery/absorption into and through the skin is important in both dermato-pharmacology and dermato-toxicology. The human stratum corneum (SC) is the fi rst layer of the skin, and constitutes a rate-limiting barrier to the transport of most chemicals across the skin (Blank, 1965). Chemicals must fi rst partition into the SC 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 SC, and the process quickly reaches equilibrium (Scheuplein and Bronaugh, 1983). In addition to binding within the SC, a chemical can also be retained within the SC as a reservoir (Zatz, 1993). Thus, understanding the process of chemical partitioning into the SC becomes important in developing an insight into its barrier properties and transport mechanisms.
