Evaluation of in vitro skin models for dermal absorption studies
Skin permeation is a major consideration in the safety assessment of cosmetics, topical drugs, and veterinary medicine products. FDA, NIH, and NIEHS scientists conducted a study to explore the usefulness of alternative skin barrier models to replace excised human skin or animal models to assess skin penetration (Salminen et al. 2023). A standardized dermal absorption testing protocol was developed to predict skin absorption in humans. Caffeine, salicylic acid, and testosterone were used in side-by-side assessments of a reconstructed human epidermis model, a synthetic barrier membrane model, and an excised human skin model. Transepidermal water loss and histology of the biological models were compared. Based on the results of this study, authors made specific recommendations about how to evaluate and use both alternative skin barrier models and excised human skin to assess skin penetration. Evaluating novel models in the manner outlined in this study has the potential to reduce the time from basic science discovery to regulatory impact.