Encapsulation of Cannabidiol in Chitosan-Stabilized Argan Oil Nanoemulsion as a Potential Dermal Drug Delivery System for Psoriasis Treatment

<b>Background</b>: Cannabidiol (CBD), a non-psychoactive compound derived from <i>Cannabis sativa</i>, exhibits therapeutic potential for various conditions, including inflammation, pain, and skin disorders, making it a promising candidate for the topical treatment of psoriasis. However, its poor water solubility and instability limit its therapeutic efficacy. This study focuses on the development and characterization of CBD-loaded nanoemulsions using argan oil as the lipid phase, with and without a chitosan coating, which serves as a stabilizing and functional biopolymer. <b>Methods</b>: Nanoemulsions (NE) and chitosan-stabilized nanoemulsions (CS-NE), both without CBD (serving as controls), and CBD-loaded variants (CBD-NE and CBD-CS-NE) were prepared and characterized for their physicochemical properties, including pH, droplet size, polydispersity index (PDI), zeta potential (ζ-potential), and viscosity at various shear rates and temperatures. Stability was assessed over time, and drug release behavior was investigated through <i>in vitro</i> diffusion and <i>ex vivo</i> skin permeation studies, followed by kinetic modeling. Safety was evaluated through <i>in vitro</i> cytotoxicity assays using HaCaT keratinocyte cells, as well as <i>in vivo</i> toxicity studies using <i>Caenorhabditis elegans</i> (<i>C. elegans</i>). <b>Results</b>: The chitosan-coated formulations exhibited enhanced physical stability, nanoscale droplet size, a positive surface charge, and increased viscosity. Release studies demonstrated that CBD-CS-NE enabled controlled and sustained drug release, with a strong correlation to the Higuchi model, indicating diffusion-controlled permeation. Cytotoxicity assays indicated that CBD-CS-NE was non-toxic to cultured cells, while <i>in vivo</i> testing with <i>C. elegans</i> revealed sensitivity to chitosan-coated systems. <b>Conclusions</b>: These findings highlight the potential of CBD-loaded argan oil nanoemulsions, particularly those stabilized with chitosan, as potential topical delivery systems for managing psoriasis.