Development of Practical Low-Volume Screening Method and Pharmacokinetic Simulation of Levofloxacin-Loaded Nanofiber Inserts for Sustained Ocular Therapy

Background/Objectives: Ocular drug delivery faces significant challenges due to anatomical and physiological barriers that limit drug bioavailability, particularly with conventional eye drops. Levofloxacin (LEVO), a broad-spectrum antibiotic, is widely used in the treatment of bacterial conjunctivitis, but its therapeutic efficacy is hindered by rapid precorneal clearance and short residence time. Methods: This study introduces a biorelevant 2 mL dissolution model to simulate ocular conditions better and evaluate the release kinetics of LEVO-loaded nanofibrous ophthalmic inserts. Compared to the conventional 40 mL setup, the 2 mL system demonstrated a slower and more sustained drug release profile, with kinetic modeling confirming a more controlled release behavior. Difference and similarity factor analysis further validated the distinct release profiles, highlighting the impact of dissolution volume on release dynamics. Results: Preliminary pharmacokinetic modeling suggested that the nanofiber inserts, particularly when applied twice daily, maintained levofloxacin concentrations above minimum inhibitory and bactericidal levels for extended durations across three bacterial strains (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus), potentially outperforming traditional eye drops. Conclusions: These findings suggest that small-volume dissolution testing may provide a more realistic method for evaluating ophthalmic insert formulations, though in vivo validation is needed. Moreover, the nanofibrous inserts show potential as a sustained-release alternative that warrants further investigation to improve patient compliance and therapeutic outcomes in ocular disease management.