Relationship between H-bonding of penetrants to stratum corneum lipids and diffusion

It is generally accepted that the barrier to permeation is effectively the outermost 10–15mm of the skin (1–3). To overcome this stratum corneum (SC) obstacle, a molecule must first enter and then cross it. Fick’s law relates the steady-state flux, Js, to the concentration gradient across the SC. If the viable dermis is regarded as a sink, the gradient determining the flux is Csc/h. Since the partition coefficient K of a solute between the SC and vehicle can be written as Csc /Cv, Js can be expressed as: Js 1⁄4 ADKCv=h