Nanoemulgel Optimization of Achatina fulica Mucus: A D-Optimal Mixture Design Approach for Enhanced Formulation and Penetration Evaluation In Vitro

Snail mucus (Achatina fulica) is an abundant natural resource in Indonesia and has garnered attention in the field of skin health. The active compound of a A. fulica mucus, namely Allantoin, has wound healing properties, which shows potential for treating cellulite. This study aimed to develop and optimize a nanoemulgel formulation containing Achatina fulica mucus. A pseudoternary phase diagram was used to determine the optimal ranges of oil, surfactant mixture (Smix), and water in the A. fulica mucus nanoemulsion formulation. The composition was optimized using a D-optimal mixture design (Design Expert ver 13) with oil (A), Smix (B), and water (C) as independent variables, and % transmittance (Y₁), droplet size (Y₂), polydispersity index (Y₃), and zeta potential (Y₄) as response variables. The optimized nanoemulsion was then combined with Carbopol 940 gel base at concentrations of 0.5%, 0.75%, 1%, and 2%. The final optimal A. fulica mucus nanoemulgel formulation consisted of 15.67% olive oil, 49.67% Tween 20:PEG 400 (2:1), 34.67% water, and 1% Carbopol 940. The average droplet size was 38.33±33.86 nm. In vitro drug penetration studies using a Franz diffusion cell with PVDF synthetic membranes showed flux values of 2114.8±49.3 μg/h/cm² for A. fulica mucus, 4832.5±54.6 μg/h/cm² for the A. fulica mucus nanoemulsion, and 3200.2±30.8 μg/h/cm² for the A. fulica mucus nanoemulgel. The increased flux observed in the A. fulica mucus nanoemulsion and nanoemulgel formulations demonstrated that the D-optimal mixture design was an effective tool for optimizing the formulation.