Topical Ethosomal Formulation of Alpha Arbutin: Dermatokinetic Study and In-vitro Evaluation

Introduction: Melasma is a skin disorder characterized by increase in melanin production causes patient inconvenience. Alpha-arbutin blocks epidermal melanin biosynthesis by inhibiting enzymatic oxidation of Tyrosine. Alpha-arbutin is hydrophilic and poorly permeates through stratum corneaum. Ethosomes enhance permeability of drugs into deeper layers and extend the release. The main goal of this study was to prepare ethosomal gel containing alpha-arbutin to enhance permeation to skin. Method: Ethosomes gel of alpha arbutin were prepared by cold method using soy lecithin, ethanol, and propylene glycol (PG) and evaluated for in vitro drug diffusion, vesicle size, entrapment efficiency and dermatokinetic study. Results: The entrapment efficiency and drug diffusion of the prepared ethosomal gel containing alpha arbutin were found to be 94.99 % and 106.63 %, respectively. The vesicle size, polydispersity index, and zeta potential of the ethosomes formulated with 20 % w/w ethanol and 4 % w/w soy lecithin were recorded as 138.1 nm, 0.406, and -48 mV, respectively. The in vitro diffusion study illustrated burst release, with 97.56 ± 0.68 % drug released at 90 minutes. At the end of 8 hours, approximately 47.85% of the drug had diffused from the ethosomal gel. The dermatokinetic study demonstrated that the retention time of the drug in the dermis and epidermis was significantly higher in the ethosomal gel compared to the marketed cream. Conclusions: Alpha arbutin was successfully formulated as an ethosomal suspension and converted into a gel. Due to the higher concentration of ethanol, drug permeation into the dermis and epidermis was significantly improved. Dermatokinetic studies demonstrated better retention of the drug in the dermis and epidermis layers compared to the marketed formulation.