Carbopol 940-based metronidazole nanogels: formulation, physicochemical characterization, in vitro drug release, and antimicrobial evaluation

Introduction Metronidazole-loaded nanogels based on carbopol 940 have been developed and characterized for their suitability as drug delivery carriers for topical antimicrobial application. Methods Formulations were prepared using dispersion-neutralization method and subsequently characterized in terms of physicochemical properties, rheological behavior, particle size, drug release, antimicrobial activity, and stability studies. Results The nanogels were found to be homogeneous and smooth with suitable pH values (5.30 ± 0.02–5.50 ± 0.02), drug content (94.70 ± 0.46%–99.94 ± 0.21%), and swelling indices (29.00 ± 0.79%–33.00 ± 0.91%). All formulations showed pseudoplastic shear thinning behavior. The optimized formulation had an average particle size of 143.4 nm and exhibited a maximum drug release of 97.03 ± 1.91% within 8 h. Zero order kinetic model explained the drug release behavior. The results of in vitro antimicrobial activity showed more efficacy against Staphylococcus aureus while there was no significant efficacy against E. coli. There were no significant changes in the physicochemical properties of the formulations after 60 days of storage at refrigerated, room temperature, and accelerated storage conditions. Conclusion The quantity of Carbopol 940 affected the physicochemical, rheological, drug release, and antimicrobial properties of the metronidazole-loaded nanogels. Formulation F3 showed the best suitability.