Design, Development and Characterisation of Eudragit Rl100-Based Besifloxacin Hydrochloride-Loaded Nanoparticle Incorporated Ion-Sensitive in Situ Ophthalmic Gel for the Treatment of Keratoconjunctivitis

Abstract

The present study focuses on the design, development, and characterization of a nanoparticle-based ion-sensitive in situ ophthalmic gel of besifloxacin hydrochloride for the effective treatment of keratoconjunctivitis. Besifloxacin hydrochloride-loaded nanoparticles were prepared using the solvent evaporation (O/W emulsification) technique employing Eudragit RL100 as the polymer, polyvinyl alcohol (PVA) as a stabilizer, and Poloxamer 407 as a co-stabilizer. The optimized nanoparticles were incorporated into a gellan gum-based ion-sensitive in situ gel system to enhance ocular residence time and provide sustained drug release. Preformulation studies confirmed the drug’s suitable physicochemical properties, with UV spectrophotometric analysis showing λmax at 290 nm and excellent linearity (R² = 0.9992). FTIR and DSC studies indicated no significant drug–excipient interactions, confirming compatibility. Among all formulations (F1–F6), formulation F6 exhibited optimal characteristics with a minimum particle size of 162.4 nm, low polydispersity index (0.280), and high zeta potential (−28.6 mV), indicating excellent stability. The formulation also showed the highest encapsulation efficiency (88.42%) and drug content (97.28%). The developed in situ gel formulations were found to be clear, with pH in the acceptable range (4.01–4.07). The sol–gel transition temperature decreased from 35°C to 29°C with increasing polymer concentration, ensuring rapid gelation at ocular temperature. Viscosity studies demonstrated low viscosity in the sol state and significant increase upon gelation, indicating enhanced retention at the ocular surface. In vitro drug release studies revealed a sustained release profile for all formulations. Notably, formulation F6 exhibited the highest cumulative drug release (91.7% at 6 hours), indicating superior performance due to optimized polymer concentration and gel matrix characteristics. In conclusion, the developed nanoparticle-loaded ion-sensitive in situ gel system demonstrated promising potential for sustained ocular delivery of besifloxacin hydrochloride, improving drug bioavailability and therapeutic efficacy in the treatment of ocular infections.