Dermal Peptide Delivery Using Enhancer Molecules and Colloidal Carrier Systems - Part IV: Search for an Alternative Model Membrane for Future ATR Permeation Studies Using PKEK as the Model Substance

The main barrier of the human skin is the stratum corneum (SC). Its properties (also depending on the health and age of the individual) and its influence on improved penetration of active ingredients into the skin are the subject of many research projects. Since the availability of human skin, as the ideal model membrane, is limited, the aim of this study was to find a suitable alternative model membrane from the animal kingdom. The alternative model membrane should be used in subsequent permeation experiments with the Teflon diffusion cell instead of human SC. Previous studies have already investigated the permeation properties of pig, snake, and human skin, but not in a Teflon diffusion cell using ATR. Therefore, it first had to be proven that comparable results can be achieved with animal membranes even under these measurement conditions. This is the precondition for meaningful future permeation experiments with potential enhancers. For this purpose, permeation experiments on various model membranes (human isolated SC, sunburned SC, pig isolated SC, and shed snake skin) by means of FTIR-ATR in a Teflon diffusion cell containing the acceptor and the donor compartment as well as the model membrane were conducted and concentration-time courses of the model peptide PKEK determined. These concentration-time courses were used to calculate and compare the pharmacokinetic parameters (permeation coefficients, lag time, and flux). The starting point was a 10% PKEK solution in D2O. It turned out that snake skin is the appropriate alternative model membrane for this type of permeation test.