Skin permeability (Kp)

Skin permeability refers to the capacity of the epidermal barrier, primarily the stratum corneum, to regulate the passage of substances from the external environment into the skin or systemic circulation (Kligman, 1984 [14]). It is fundamentally a pharmacokinetic property rather than a molecular target, acting as the rate-limiting step in transdermal drug delivery (Research J. Pharm. and Tech., 2015 [13]). The barrier's biological function is to maintain homeostasis by preventing transepidermal water loss and shielding against pathogens and environmental toxins (DermNet [10]). In diseases like atopic dermatitis and psoriasis, skin permeability is often pathologically increased due to defects in the lipid matrix or proteins like filaggrin, leading to inflammation and increased susceptibility to infection (JCAD, 2021 [6]; PMC8119241 [12]). Chemical penetration enhancers, such as dimethyl sulfoxide (DMSO) or propylene glycol, are commonly used in pharmaceutical formulations to reversibly increase permeability by fluidizing or extracting lipids within the stratum corneum (ACS Pubs, 2023 [1, 4]). Understanding skin permeability is critical for biotech analysts to evaluate both the therapeutic potential of topical formulations and the safety risks associated with the systemic absorption of active agents (Fitzpatrick's Dermatology [19]).

Other names

Percutaneous absorptionDermal penetrationCutaneous permeabilitySkin barrier functionDermal absorption

Chemical penetration enhancers increase skin permeability by fluidizing the stratum corneum lipid bilayer, extracting lipids, or altering the protein structures of corneocytes to reduce the diffusion resistance of the epidermal barrier.