Self-assembled organogelators as artificial stratum corneum models: key-role parameters for skin permeation prediction

Self-assembled organogelators were explored as artificial stratum corneum (SC) models for the in vitro skin permeation assessment. Four SC models consisting of binary (organogels) or ternary (microemulsion-based organogels) mixtures were developed using stearic acid, tristearin, or sorbitan tristearate, at two different concentrations, gelled in squalene. The permeation of lipophilic butyl-methoxydibenzoylmethane and hydrophilic methylene blue as the permeant compounds across the SC models was compared with ex vivo experiments using excised porcine ear skin. A multi-analytical approach was adopted to provide detailed understanding about organogelator organization within the SC models and find possible parameters playing key-roles in SC permeation prediction. The SC models were investigated for gelling properties and microstructure. Parameters such as gel occurrence, organogelator concentration, and rheological properties appeared as negligible conditions for skin permeation prediction. Conversely, arrangement packing, interactions, and crystallinity extent of the self-assembled organogelator were found to play a fundamental role in the simulation of SC barrier function according to the permeant feature.