Poly(dimethylsiloxane): A Sustainable Human Skin Alternative for Transdermal Drug Delivery Prediction.

Despite the advantages of transdermal drug delivery (TDD), which makes it a fast-growing area of research in pharmaceutics, numerous challenges affect their development, which limits exploring the full potential of this alternate drug delivery route. In trying to address one of these problems, it is strongly believed that the need for a sustainable skin alternative is paramount. Efforts made in an attempt to provide a sustainable alternative to employing skin in pharmaceutical analysis, by better utilising a polymer membrane, namely poly(dimethylsiloxane), also known as PDMS are discussed. Several combined properties of this polymer, which includes its relative stability in comparison with human skin, make it a good candidate for the replacement of skin. Modifications undertaken to this polymer membrane (to create an enhanced skin mimic for permeation analysis) are discussed and reviewed in this paper, including the improved ability to predict permeability for both hydrophobic and hydrophilic drugs. Optimisations related to studying TDD including limitations encountered are also documented and reviewed. It is hoped that such developments in this field will ultimately lead to researchers replacing skin with optimised polymer-based alternatives to predict transdermal drug delivery.

Permeation of Pharmaceutical Compounds Through Silanized Poly(dimethylsiloxane).

This work evaluates permeation of 12 model pharmaceutical compounds through a chemically modified form of poly(dimethylsiloxane), whereby the polymer surface had undergone silanization. Standard polymer membrane has been widely used as a simplified skin model to investigate transdermal permeation yet does not fully mimic human skin. The surface chemistry of modified polymer was investigated such as the ability to bind to drugs, hydrophobicity and pore size using optical microscopy, the Brunauer-Emmett-Teller technique and Fourier-transform infrared spectroscopy, followed by permeation analysis with UV spectroscopy. For 11 of the 12 compounds, an appreciable increase in the extent of permeation was observed after 6 h when using the silanized polymer compared with the standard poly(dimethylsiloxane). Furthermore, a correlation was found between the degree of permeation increase and hydrophobicity (logP) of the drug (R2 = 0.90). These findings indicate that permeation can be controlled by modifying the membrane surface, although the hydrophobicity of the permeant also plays a vital role in the extent of permeation observed. This concept study presents a potential alternative membrane for pharmaceutical transdermal analysis, providing many benefits over existing options.