Comparison of the Effect of Skin Preparation Pads on Transepidermal Water Loss in Ex Vivo Human Skin

Introduction: Pre-treatment of the skin to remove scales and crusts prior to photodynamic therapy (PDT) is essential to enhance the uptake of topically applied methyl aminolevulinate (MAL) and to improve treatment efficacy. This study compared the effect of two different skin preparation pads on skin integrity in ex vivo human skin. Methods: Ex vivo human skin samples from three donors were pre-treated in triplicates with PREPSTER TM (PR) skin preparation pad (6, 8, and 10 passages) or Ambu Unilect TM (A-UN) skin preparation pad (6, 8, and 10 passages). In addition, skin samples were pre-treated with tape strippings (10 adhesive tape strips) as a reference method for comparison. Transepidermal water loss (TEWL) was measured on intact skin and following skin barrier impairment using skin preparation pads and tape stripping. Histological analysis was performed to verify the impairment of the stratum corneum (SC) barrier function in samples from intact skin (control), 10 tape strippings (reference method), 10 passages of PR, and 10 passages of A-UN. Results: TEWL increased with the increasing number of passages of skin preparation pads, with 2.4-and 3.3-fold increases following 10 passages of A-UN and PR, respectively, versus a 2.2-fold increase with 10 tape strippings (reference). Histological analysis showed only partial removal of the SC, with no damage observed on the epidermis, regardless of the procedure used. Conclusion: Pre-treatment of skin using PR and A-UN skin preparation pads markedly increases TEWL, indicating slight impairment of the SC barrier function. Comparison of both skin preparation pads showed that PR pad consistently induced significantly higher TEWL than A-UN pad (p\ 0.05), regardless of the number of passages. Both skin preparation pads are thought to increase the uptake of MAL and can therefore be used for the preparation of skin prior to PDT.