What is the Origin of Transdermal Flux?

The concept is derived from Fick's laws of diffusion, which govern the movement of molecules across a concentration gradient, applied specifically to the biophysics of skin permeability. The term combines 'transdermal,' meaning across the skin, with 'flux,' a physics term for the rate of flow or transfer. Pharmaceutical scientists use this parameter to characterize the performance of different drug delivery vehicles.

What is the Mechanism of Transdermal Flux?

The magnitude of the transdermal flux is primarily determined by the concentration gradient of the hormone between the formulation and the skin, the physicochemical properties of the hormone (e.g., molecular weight and lipophilicity), and the permeability of the skin barrier. The vehicle formulation plays a crucial role by containing permeation enhancers that temporarily and reversibly disrupt the stratum corneum barrier, facilitating the steady movement of the hormone molecules into the deeper dermal layers for systemic absorption.

Transdermal Flux ∞ Area

Transdermal Flux

Meaning

Transdermal Flux is a quantitative measure in pharmacology that describes the rate and amount of a substance, such as a steroid hormone, that passes through a defined area of the skin per unit of time. This metric is critical for determining the bioavailability and dosing of topical hormone delivery systems, ensuring the formulation provides the intended therapeutic concentration in the systemic circulation. Optimizing transdermal flux is essential for achieving clinical efficacy with transdermal patches and gels.