Abstract
Understanding the heterogeneous barrier property and permeation pathway of the skin is important for skin health, transdermal drug delivery, cosmetic care as well as the protection of the skin from environmental exposure to air pollution and harmful chemicals. This chapter reviews recent progress in microscopic modeling of the heterogeneous barrier property and permeation pathway of the stratum corneum (SC) barrier and their effects on the dermatopharmacokinetics and bioavailability of dermal exposure. The microscopic structure parameters of the human SC barrier depend on a number of factors such as body site, age, and sex. Studies of microscopic modeling of transdermal permeation focused on the lipid pathway, using the homogenized 1D model of solute permeation across the SC membrane at steady state. The chapter discusses the progress in applying microscopic modeling for in silico prediction of the dermatopharmacokinetic and bioavailability. Predicting systemic pharmacokinetics following dermal exposure is important for the purpose of efficacy and safety assessment.