Thermosensitive and pH induced in situ ophthalmic gelling system for ciprofloxacin hydrochloride: hydroxypropyl-beta-cyclodextrin complex.

The prolonged residence of drug formulation in the ocular cavity is important for ocular drug delivery. The purpose of the present study was to develop ophthalmic in situ gelling systems of ciprofloxacin hydrochloride with reduced pre-corneal elimination in order to improve the bioavailability and therapeutic response. Hydroxypropyl-beta-cyclodextrin was used in order to increase the stability of ciprofloxacin hydrochloride. In situ gels were prepared based on the concept of thermosensitive and pH induced in situ gelation. The inclusion complex of ciprofloxacin hydrochloride with hydroxypropyl-beta-cyclodextrin was prepared at a 1:1 molar ratio. The complex formation was thoroughly confirmed using various techniques, including (1)H NMR spectroscopy, FTIR spectrophotometry and differential scanning calorimetry. Both pure ciprofloxacin HCI and the inclusion complex were individually used in the formulations. Formulations were successfully prepared which were liquid at room temperature and exhibited viscosity increase and gelation at ophthalmic temperature. As a result of antimicrobial efficacy and in vitro release experiments, the developed formulations were found therapeutically efficient and provided sustained release of the drug over an 8 h period. These systems can be more advantageous than conventional eye drops.