The objective of the present research was to develop a temperature triggered in situ
gelling system for ophthalmic delivery of Ofloxacin (OFL) which is used in acute and subacute
conjunctivitis of eye. For this purpose, Pluronic F127 (PF127) was used as in situ gelling agent in
combination with Chitosan (CTS) as a natural, biodegradable and mucoadhesive hydrophilic
copolymer. The formulations were prepared using PF127 alone and various concentrations in
mixture with CTS. In situ gels were evaluated for clarity, pH, gelling temperature and the rheological
behaviors. Desired characteristics were obtained in five of the formulations. Selected formulations
were clear and in a pH range of 5.0-6.7. The gelation temperatures were between 30-34oC and found to exhibit
pseudoplastic behavior. Gelation temperatures of the formulations increased with the decrease of concentration of PF127.
Also the use of the pH 6 buffer as solvent in the formulations led to a reduction in the gelation temperature. For the
selected formulations, 0.3% ofloxacin was added to in situ gelling system and release of ofloxacin was evaluated by
dissolution study. Release of OFL decreased with the increase of PF127 concentration in the formulations. The slowest
release was obtained by the mixture of 15% PF127 and 30mL CTS solution (1% CTS in water). The results demonstrated
that the composition of PF127 and CTS can be a promising in situ gelling vehicle for ocular delivery of OFL.
Keywords: Chitosan, gelation temperature, in Situ gel, ocular delivery, ofloxacin, poloxamer, rhelogical behavior.
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