Formulation, Characterization and Evaluation of Polymeric Nanospheres-Based Colon-Targeted Delivery of Oxiconazole Nitrate

Oxiconazole nitrate-loaded nanospheres were successfully developed using the emulsification–solvent evaporation method to enhance the solubility and dissolution of oxiconazole nitrate, a Biopharmaceutics Classification System (BCS) Class II antifungal drug characterized by low aqueous solubility and good membrane permeability. Oxiconazole exerts its antifungal activity by inhibiting lanosterol 14-α-demethylase (CYP51), thereby disrupting ergosterol biosynthesis, compromising fungal cell membrane integrity, and ultimately causing cell lysis. Eudragit RS 100 was employed as the polymeric carrier, with methanol serving as the solvent. The prepared nanospheres were evaluated for particle size, percentage yield, entrapment efficiency, solubility enhancement, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), zeta potential, and in vitro drug-release characteristics. Among the formulations, batch F5 demonstrated optimum performance, exhibiting an entrapment efficiency and percentage yield of 83.40%, an average particle size of 11.8 nm, and enhanced aqueous solubility in phosphate buffer (pH 7.4). FTIR and DSC analyses confirmed the absence of significant drug–polymer interactions and demonstrated the thermal stability of the formulation. The optimized formulation exhibited a zeta potential of −80.9 mV, indicating excellent colloidal stability. Furthermore, the nanosphere gel (G2) achieved 98.13% drug release within 6 hours, confirming that nanosphere formulation significantly improved the solubility and dissolution behaviour of oxiconazole nitrate.