PREPARATION, DEVELOPMENT AND IN VITRO EVALUATION OF RETAPAMULIN LOADED GLYCEROSOMES FORMULATION

The present study aimed to develop, optimize, and evaluate Retapamulin-loaded glycerosomes using a Quality by Design (QbD) approach. Preformulation studies showed that Retapamulin was a white to off-white, odorless crystalline powder with poor aqueous solubility. The melting point was found to be 128°C and the λmax was observed at 249 nm. A linear calibration curve was obtained over the concentration range of 10–50 μg/mL. FTIR analysis confirmed the characteristic functional groups of Retapamulin. A Box–Behnken design using Response Surface Methodology was employed to optimize the formulation, with phospholipid, cholesterol, and glycerol concentrations as independent variables and particle size and entrapment efficiency as responses. The optimized formulation showed a particle size of 322.7 nm, zeta potential of −30.2 mV, and entrapment efficiency of 97.52%. The predicted values for particle size and entrapment efficiency were 319.313 nm and 95.129%, respectively, showing good agreement with the experimental results. SEM analysis revealed predominantly spherical to oval vesicles with smooth morphology and no significant aggregation. In vitro drug-release studies indicated that the formulation followed Higuchi and Korsmeyer–Peppas models, suggesting predominantly diffusion-controlled release with possible anomalous transport. Overall, QbD-assisted optimization successfully produced Retapamulin-loaded glycerosomes with desirable physicochemical characteristics and promising controlled-release properties for topical drug delivery.