Assessing the Relevance of Ion and Molecule Transport Through Animal Skin and Fascia to Transdermal Drug Delivery Systems

Abstract

Biological membranes such as the skin and fascia play a critical role in controlling the transport of ions and molecules and, as such, they are often used as substitutes to study the transdermal delivery of drugs. This paper uses the conductivity data from ion-transport experiments performed with broiler chicken, indigenous chicken (Kadaknath and Gavran), goat and sheep skin that were exposed to KCl and NaCl solutions of 0.1 N-0.5 N for 120 minutes to examine if the variations observed in permeability data suggest anything about the membrane’s potential as a model for transdermal drug delivery (TDD). The data shows that, in general, conductivity increased linearly with time and ion concentration in all tested membranes, though the chicken and goat skin showed significantly higher flux than their indigenous counterparts, suggesting that their permeability can differ considerably for a given set of conditions, which is an important consideration for selecting the animal model for TDD studies. By reviewing the data in the context of the existing pharmaceutical literature on percutaneous absorption, iontophoresis and skin-impedance modeling, the paper shows that measuring conductivity is a viable option to prioritize membranes for further studies, such as Franz-cell experiments or iontophoretic drug delivery trials. The paper concludes by discussing the limitations of this study, including the lack of data on fascia and the absence of permeability coefficients required for quantitative analysis.