Pretreatment of skin using an abrasive skin preparation pad, a microneedling device or iontophoresis improves absorption of methyl aminolevulinate in ex vivo human skin

Abstract Background Pretreatment of skin to remove scales/crusts and roughen the surface is essential to enhance the penetration of topically applied methyl aminolevulinate (MAL) prior to photodynamic therapy and to permit daylight to access all parts of the skin lesions. Numerous procedures of skin preparation are currently available. This study compared the in vitro penetration of MAL into ex vivo human skin pretreated with skin preparation pad abrasion or a microneedling device, and evaluated the effectiveness of an iontophoretic device in delivering MAL into ex vivo human skin. Methods Human skin samples, obtained from aesthetic surgeries, were used in this study. The thickness of the skin samples ranged between 1.44–2.87 mm. Pretreatment of samples was performed with 10 passages of the Ambu ® Unilect™ 2121 M (Ambu A/S, Denmark) skin preparation pad, 8 rolling repetitions using the microneedling device Dermaroller ® HC 902 (Dermaroller GmbH, Germany), or by an iontophoresis device (Feeligreen SA, France) for 1.5 h. The effect of these pretreatment procedures on the penetration of MAL into the skin was assessed. Results Penetration in the total skin, liquid receptor and total penetration was most increased by skin preparation pad treatment, followed by microneedling and iontophoresis. Overall, MAL total penetration was increased up to 103-fold by skin preparation pad treatment, 4-fold by microneedling and 1.8-fold by iontophoresis. Conclusions Abrasion with skin preparation pad was shown to be superior to microneedling and iontophoresis for increasing MAL penetration in ex vivo human skin.