Lanolin-Based Synthetic Membranes for Transdermal Permeation and Penetration Drug Delivery Assays

Abstract

Due to the high similarity in composition and structure between lanolin and human SC lipids, we will work with two models from wool wax. Two types of lanolin were evaluated: one extracted with water and surfactants (WEL) and the other extracted with organic solvents (SEL). Skin permeation and skin penetration studies were performed with two active compounds to study the feasibility of the use of lanolin-based synthetic membranes as models of mammalian skin. Diclofenac sodium and lidocaine were selected as the active compounds considering that they have different chemical natures and different lipophilicities. In the permeation assay with SEL, a better correlation was obtained with the less permeable compound diclofenac sodium. This assay suggests the feasibility of using artificial membranes with SEL as a model for percutaneous absorption studies, even though the lipophilic barrier should be improved. Penetration profiles of the APIs through the SEL and WEL membranes indicated that the two membranes diminish penetration and can be considered good membrane surrogates for skin permeability studies. However, the WEL membranes, with a pH value similar to that of the skin surface, promoted a higher degree of diminution of the permeability of the two drugs, similar to those found for the skin.

Keywords: lanolin; penetration; permeation; skin; synthetic membranes.

Figure 1

Normalized permeated amounts (%) in the skin, Nuclepore^®, Nuclepore^®-SEL for lidocaine, and diclofenac sodium. (*) denotes a p-value ≤ 0.05 from the test of Kruskal Wallis.

Figure 2

Average percentage release of lidocaine (LIDO) and diclofenac sodium (DS), through Nuclepore^®, 5% SEL and 5% WEL membranes and average percentage permeation of these compounds through the skin.