The major steps in transdermal permeation are: 1) partitioning of the permeants in the outermost layer of the stratum corneum (with keratin-filled corneocytes anchored in a lipophillic matrix), 2) diffusion after partitioning through the stratum corneum, then 3) further partitioning at the stratum corneum/viable epidermis junction as the permeant diffuses through the junction into viable tissue an