Microneedles mediated-dermal delivery of Vitamin C: Formulation, characterization, cytotoxicity, and enhancement of stability

Vitamin C (VIT C) is an antioxidant that prevents skin aging. Although dermal delivery is one of the most effective routes to transport VIT C to the skin, the impact of this route can be limited by the barrier function of the <i>stratum corneum</i> (SC). Additionally, VIT C rapidly oxidized and degraded under light and temperature. Therefore, this study provides an approach to utilizing microneedles (MNs) to improve the dermal delivery of VIT C and enhance its stability by incorporating a stabilizing system of ethylenediaminetetraacetic acid (EDTA) and sodium metabisulfite (Meta) within the MNs. Vitamin C microneedles (VIT C MNs) were fabricated using different biodegradable polymers and various concentrations of EDTA/Meta. VIT C MNs were evaluated for morphology, VIT C content, mechanical properties, dissolution rate, needles' insertion, physicochemical properties, <i>ex vivo</i> permeation, viscosity of VIT C polymeric solutions, cytotoxicity, and stability. The results showed that VIT C MNs were uniform and mechanically strong. The recovery of VIT C in MNs was 88.3-90.0 %. The dissolution rate of MNs was <30 min. The flux of VIT C varied based on the composition of MNs. VIT C MNs demonstrated safety against human dermal fibroblasts. VIT C MNs with EDTA/Meta (0.1/0.3 %) were stable under different storage conditions for two months. In conclusion, VIT C MNs were successfully developed using biodegradable polymers, and the stabilizing system (EDTA/META) provided a stable dermal delivery system for VIT C to protect skin from aging.