Levofloxacin hemihydrate ocular semi-sponges for topical treatment of bacterial conjunctivitis: Formulation and in-vitro/in-vivo characterization

This study aimed to formulate and evaluate lyophilized, long acting, levofloxacin hemihydrate ocular semi-sponges that would fit cul-de-sac shape for bacterial conjunctivitis treatment. Formulae were prepared using casting/freeze drying technique employing a (41 × 31) full factorial design to examine the effects of polymer type (Gelrite, chitosan (low and high molecular weight), and sodium carboxymethylcellulose), and concentration (1%, 1.5%, 2%) on viscosity of the formed solutions, quantity of drug released after 12 h (Q12h) and time for 50% of the drug to be released (T50%). Formulae were evaluated for weight and content uniformity, surface pH, water uptake, and in vitro drug release with its kinetic analysis. The optimal formula was chosen using Design-Expert® software and subjected to scanning electron microscope imaging, γ-sterilization and in-vivo evaluation. Results showed that formula G 2 (2% w/w Gelrite) had the highest desirability (0.894), a zero order drug release profile, and stability after γ-sterilization. Formula G 2 showed longer residence time (12 h) in rabbits' eye fluids compared to the commercial Levoxin® eye drops (4 h) with good correlations between in vitro and in vivo results. Conclusively, Gelrite ocular levofloxacin hemihydrate semi-sponges are promising drug delivery systems that would improve both patient compliance and treatment efficacy.

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