ABSTRACT:
The poor bioavailability and therapeutic response exhibited by conventional ophthalmic solutions due to rapid pre-corneal elimination of the drug may be overcome by the use of in situ gel forming systems that are instilled as drops into the eye and then undergo a sol-gel transition in the cul-de-sac. The present work describes the formulation and evaluation of an ophthalmic delivery system of an antibacterial agent moxifloxacin hydrochloride, based on the concept of pH triggered in situ gelation. Carbopol 940 was used in different concentrations (0.3-0.5 w/v) as the gelling agent in combination with HPMC E50 LV (Hydroxy Propyl Methyl Cellulose) that acted as a viscosity-enhancing agent. The primary criteria for formulation optimization were gelling capacity and rheological behaviour. In addition, formulations were evaluated for pH, and antimicrobial efficacy and drug release. The clarity, pH, gelation in simulated tear fluid and rheological properties of the optimized formulations were satisfactory. In vitro release studies indicated that the Carbopol /HPMC solution retained the drug better than the Carbopol or HPMC solutions alone. The formulations were therapeutically efficacious, sterile, stable and provided sustained release of the drug over a period of time. These results demonstrate that the developed system is an alternative to conventional ophthalmic drops, patient compliance, industrially oriented and economical.