Formulation and optimization of chrysin emulgel using 3 ² factorial design of emulsifying and gelling agent for enhanced topical delivery

This study focused on the development and optimization of a chrysin-loaded emulgel for enhanced topical delivery using a 3² factorial design. Preformulation and compatibility studies, including FTIR and DSC, confirmed the chemical stability of chrysin with selected excipients, carbopol 934, tween 80, and light liquid paraffin. By using 3² factorial design, a total 9 formulations were prepared (F1-F9), employing different concentrations of carbopol 934 and tween 80 as independent variables. The prepared formulation was evaluated for drug content, viscosity, in-vitro drug release, globule size, pH, spreadability, and stability. The optimized formulation was identified through statistical analysis, response surface methodology (RSM), and overlay plots of independent variables versus dependent responses. In the results, drug content uniformity (96.34%-98.25%) viscosity (553.25-736.38 cP), globule size (7.57-13.7 µm), drug release (78.34%-86.26%), pH (6.44-6.82) and spreadability (17-22 g cm/s) were all within the acceptable range for emulgel. The RSM and overlay plots identified F3 as an optimized formulation with a desirability score of 0.986. The optimized formulation demonstrated ideal performance with the viscosity of 647.38 cP, globule size of 10.23 µm, drug release of 82.57%, drug content of 98.25%, pH of 6.68, and spreadability of 20 g·cm/s. The optimized formulation composed of chrysin (1%), light liquid paraffin (7.5%), mentha oil (4%), tween 80 (1.5%), carbopol 934 (3%), and methylparaben (0.03%). In-vitro permeation studies showed sustained drug diffusion over 12 h (112.72 µg/cm²), without an initial burst, indicating controlled release behavior. The developed emulgel system presents a promising approach for the effective topical delivery of chrysin.