Formulation Development of Dual Drug-Loaded Thermosensitive Ocular In Situ Gel Using Factorial Design

Purpose To overcome the problems of low bioavailability of the drug associated with the short pre-corneal residence time, a thermoresponsive in situ gel system containing poloxamer P407, hydroxypropyl methylcellulose, and chitosan was developed to prolong the pre-corneal residence time of the drug. Methods The central composite design was utilized to assess the effects of the concentration of poloxamer 407 hydroxypropyl methylcellulose and chitosan, the concentration of polymer, and the polymer type on the viscosity, pH, and gelation temperature, which were considered indicators of optimum formulations. Results After model selection for response analysis, the quadratic model was found to be the best-fitting model for the relationship between independent factors and response variables. As a result of the central composite design, the optimized formulation contained 15.17% poloxamer 407 and 2.141% chitosan. Viscosity 25 °C = 2199.4 ± 26.2, viscosity 35 °C = 15,487.2 ± 117.4, pH = 6.5 ± 0.01, and gelation temperature °C = 33.3 ± 0.47 were obtained. The ex-vivo study revealed that the BRN formulation containing flurbiprofen-cyclodextrin inclusion complex has higher corneal penetration ( P < 0.01). The cytotoxicity of ARPE-19 cells and irritation studies, as measured by in situ gel, was found to be acceptable. In lipoxygenase studies, the effectiveness of the BRN formulation was found to be significantly higher than other formulations ( P < 0.01). Conclusions It is thought that the BRN formulation may be an alternative to the treatment of ocular allergic disease.