Ophthalmic controlled release in situ gelling systems for ciprofloxacin based on polymeric carriers

The objective of the present study was to design controlled release ophthalmic delivery systems for ciprofloxacin based on polymeric carriers that undergo sol-to-gel transition upon change in pH or in the presence of cations in an attempt to prolong the effect of ciprofloxacin and improve its ocular bioavailability. Carbopol and alginates polymers were used to confer gelation properties to the formulations. Hydroxypropyl methylcellulose and methylcellulose were combined with carbopol to increase the viscosity of the gels and to reduce the concentration of the incorporated carbopol. The release exponents (n) for the designed systems were close to 1, indicating that the drug release occurred by zero-order kinetics. Controlled release in situ gels consisting of carbopol and cellulose derivatives showed an increase in viscosity, gelling capacity, and adhesiveness as the concentration of each polymeric component was increased. On the other hand, these parameters possessed lowest values when alginate was used as an in situ gelling agent. The antimicrobial efficiency of the selected formulation against gram-positive and gram-negative organisms including Echerichia coli, staphylococcus strains and Pseudomonas aeruginosa confirmed that the designed formulation has prolonged the antimicrobial effect of ciprofloxacin and retained its properties against bacteria.