Alternative approach for delivery of a depigmenting agent via dissolving microneedle arrays: Formulations and in vivo efficacy

Abstract

Dissolving microneedle (DMN) arrays have gained attention as a carrier for cosmetic or pharmaceutical active compounds since they can bypass the stratum corneum to ensure delivery beyond the epidermis. In this study, we were curious whether using sodium hyaluronate (HYA) alone would be enough to fabricate DMN arrays that could yield the effective intradermal delivery and we aimed to fabricate a new concept to deliver a depigmenting agent for anti-hyperpigmentation. Thus, DMN arrays were cast by HYA with different molecular weights (MWs) and loaded with ethyl ascorbic acid (EAA). Mechanical and biological performances of DMN arrays were investigated both in vitro, ex vivo, and in vivo. The results showed that combinations of two types of HYA provided adjustable mechanical characteristics. The DMN arrays contained low MW HYA, medium MW HYA, and EAA at 70:30:20 gave the optimal in vitro properties and were selected to examine further in UVB-induced hyperpigmentation guinea pigs. The delivery of EAA, whether through the EAA-loaded DMN or the EAA solution on the pretreated skin with blank DMN, resulted in an increase in the whitening index. Hence, these two intradermal approaches demonstrated great promise and effectiveness in combating hyperpigmentation.