A Quality-by-Design Approach Based Formulation, Optimization, In Vitro and Ex Vivo Evaluation of Delafloxacin-Loaded Ethosomal Gel.

The current work aims to fabricate and examine a delafloxacin (DFX)-loaded ethosomal (ETHs) gel for improved topical delivery and improved antibacterial efficiency against skin infections. ETHs were prepared using the cold method followed by two-stage homogenization, involving vesicle fabrication and subsequent gel conversion. A Quality by Design framework was employed, with initial screening using a fractional factorial design and optimization through a Box-Behnken design. Entrapment efficiency (EnE), Vesicle size, and PDI were chosen as critical quality attributes. The optimized nanoformulation was evaluated for size, morphology, drug release, cytotoxicity, irritation potential, ex vivo studies antimicrobial activity, and skin safety. The optimized DFX-ETHs exhibited a vesicle size of 263.6 ± 3 nm, zeta potential of - 5.99 ± 1.466 mV, PDI of 0.173 ± 0.019, and EnE of 90.17 ± 0.14%. FE-SEM confirmed globular vesicles with a smooth surface. The formulation showed sustained drug release following Weibull kinetics. Cytotoxicity studies on NIH/3T3 cells and irritation studies using HET-CAM and rat skin models confirmed the cytocompatible and non-irritant nature of the formulation. Enhanced antimicrobial activity against Staphylococcus aureus and Cutibacterium acnes was observed compared to DFX dispersion. The ex vivo studies results showed that the ETHs formulation significantly improved drug permeation relative to the free DFX. The results demonstrate that ethosomal gel systems are a potential and safe carrier for the topical application of DFX, offering improved antibacterial efficacy against bacterial skin infections.