Physicochemical Characterization, Cytotoxicity, and Antimicrobial Activity of Polymeric Nanoparticles for Ocular Delivery of Norfloxacin

Abstract Ocular infections, can lead to severe complications, and may result in vision loss, if not treated effectively. Norfloxacin (NFX), a broad-spectrum fluoroquinolone antibiotic, acts by inhibiting bacterial DNA replication and transcription and is effective against drug-resistant pathogens commonly associated with serious ocular infections. However, its poor water solubility limits its therapeutic potential for ocular delivery. In this study nanoparticles was formulated with Eudragit® RS 100 (ERS100) and Polycaprolactone (PCL) to enhance the ocular bioavailability of NFX. The nanoparticles were prepared using the spray-drying method. According to the characterization studies the optimized formulation exhibited a particle size of 383.43 ± 8.01 nm, a low PDI of 0.135 ± 0.01, and a positively charged zeta potential of + 34.97 ± 0.22 mV, indicating excellent stability and favorable interaction with the negatively charged ocular surface, which may enhance the ocular bioavailability of NFX. Cytotoxicity studies using the MTT assay on the human retinal pigment epithelial cell line (ARPE-19) confirmed the ocular safety of the nanoparticles, as their IC 50 values vastly exceeded their minimum inhibitory concentrations (MICs), indicating a broad therapeutic safety margin. Antimicrobial efficacy was further confirmed through disk diffusion and MIC assays. Based on the obtained results, it can be concluded that ERS100–PCL-based nanoparticles have strong potential as an effective ocular delivery system for NFX in the treatment of severe ocular infections.