Topical Drug Delivery

Abstract

Skin barrier function is primarily controlled by the stratum corneum. Key determinants of skin permeability are drug lipophilicity, size and solubility. While many topical formulations are available to treat skin disease, the efficiency of these products – in terms of the fraction of dose delivered – is limited. To provide safer and more effective topical therapy requires improved formulations with lower drug loads that can sustain delivery into the skin throughout the dosing period; that is, the residual phase post‐application of the formulation must also be designed to maintain drug release into the barrier. To facilitate the optimisation of topical products, objective methods to assess the rate and extent of drug input into the skin are being developed and validated.