Transepidermalt

Transepidermalt is a term that is not widely used in formal dermatology literature. Some writers employ it as a shorthand for processes involving the movement of substances across the epidermis. In standard dermatology and pharmacology, the phenomenon is usually described with terms such as transepidermal transport or percutaneous absorption.

Definition and scope: the concept denotes the passage of molecules from the skin surface through the epidermal layers and into deeper tissues or systemic circulation. The epidermis serves as a barrier, but under certain conditions substances can permeate it to varying extents.

Mechanisms and factors: transport is largely governed by passive diffusion driven by concentration gradients. Molecular size, lipophilicity, and ionization state influence permeation, as do formulation factors such as vehicle, solvents, and occlusion. Carrier systems and penetration enhancers can modify transepidermal movement.

Relevance and measurement: when used, transepidermalt aligns with topical drug delivery and cosmetic science where permeation is evaluated using in vitro methods, such as Franz diffusion cells, and analytical techniques to quantify permeated material. Safety considerations include irritation and sensitization risks with higher permeation.

Note: the term is not widely standardized, and researchers typically use transepidermal transport, percutaneous absorption, or skin permeation to describe similar processes. The lack of a formal definition means usage may vary between sources.