Enhancement of lomefloxacin Hcl ocular efficacy via niosomal encapsulation: in vitro characterization and in vivo evaluation

The aim of this study is to develop and evaluate niosomal dispersions loaded with the hydrophilic drug; lomefloxacin Hcl (LXN) for the management of ocular bacterial conjunctivitis. LXN-loaded niosomes were prepared by the thin film hydration method following a full factorial formulation design. Two independent variables were evaluated: the type of surfactant (X1) and the surfactant:cholesterol ratio (X2). The dependent variables comprised entrapment efficiency (EE%: Y1), particle size (PS: Y2) and zeta potential (ZP: Y3). The optimum formulation, N-LXN14 (Tw60: CH, 1:1), was spherical in shape and exhibited EE% of 68.41 +/- 0.07, PS of 176.0 +/- 0.98 and ZP of -40.70 +/- 2.20 with a sustained release profile over 8hours following the Higuchi model. N-LXN14 proved good physicochemical stability under refrigeration up to 3 months. Ocular irritancy test showed no signs of ocular toxicity, confirming the safety and suitability for ocular application. Microbiological evaluation of the antibacterial effect of N-LXN14 was conducted using the susceptibility test and through the induction of topical conjunctivitis by Staphylococcus aureus (S. aureus) followed by topical therapy. Susceptibility test manifested significantly higher percent inhibition of S. aureus and higher AUC(0-12h) of N-LXN14 (604.59 +/- 0.05) compared to the commercial product (126.25 +/- 0.049). Both clinical observation and colony count of the infected eyes after eight days of treatment demonstrated significant improvement in therapeutic response. The infected eyes were completely healed with eradication of S. aureus. In conclusion, the results showed that LXN niosomal dispersions may serve as a promising superior ocular delivery system in the treatment of bacterial conjunctivitis.