Volume-1 ,Issue-4, November-2025

Ocular drug delivery is limited by rapid precorneal elimination, resulting in poor bioavailability and frequent dosing. This study aimed to develop and evaluate moxifloxacin hydrochloride in situ gelling formulations using sodium alginate and hydroxypropyl methylcellulose (HPMC) to enhance ocular retention and sustain drug release. Six prototype formulations (F1–F6) with varying polymer concentrations were prepared and characterized for physicochemical properties, rheology, in vitro gelation, drug content, in vitro release, antimicrobial efficacy, ocular tolerability, and stability. All formulations were clear, isotonic, and exhibited pseudoplastic (shear-thinning) behavior. In situ gelation in simulated tear fluid occurred rapidly, with higher polymer formulations (F5, F6) forming stronger gels that persisted for over 6 hours. In vitro release studies demonstrated a polymer concentration-dependent sustained release, with F6 releasing ~78% of moxifloxacin over 8 hours, following diffusion-controlled kinetics (Higuchi model; n ≈ 0.5). Agar diffusion assays confirmed that sustained-release gels retained full antibacterial activity against Staphylococcus aureus and Escherichia coli. Draize tests in rabbits indicated excellent ocular tolerability, with no significant irritation observed, and accelerated stability studies showed negligible changes in formulation characteristics. Based on these results, F6 (0.4% alginate + 0.6% HPMC) was identified as the optimized formulation, offering sustained moxifloxacin delivery, prolonged ocular residence, and good stability, suggesting its potential as a patient-friendly ophthalmic therapy with reduced dosing frequency.

Keyword: Moxifloxacin, Ophthalmic in situ gel, Sodium alginate, HPMC, Sustained release, Ocular drug delivery