Systematic development and optimization of in-situ gelling system for Moxifloxacin Ocular nanosuspension using high pressure homogenization with improved encapsulation efficiency.

Background: The objective of this study was to apply Quality by Design (QbD) principles on process parameter optimization for the development of hybrid delivery system (combination of (SLNs) and In-situ gelling system) for hydrophilic drug Moxifloxacin Hydrochloride (MOX) to achieve its controlled delivery, which otherwise may not be possible through single type of technology. Methods: Risk assessment studies were carried out to identify probable risks influencing CQAs on the product. In design of experiments (DoE), the process parameters (independent variables) i.e., chiller temperature X1, High Pressure Homogenization (HPH) pressure X2, and HPH cycles X3 were optimized using a three-factor two level face-centered central composite design to streamline the influence on three responses, namely encapsulation efficiency Y1, particle size Y2 and outlet temperature Y3. Independent and dependent variables were analyzed to establish a full-model second-order polynomial equation. F value is used to confirm the omission of insignificant parameters/interactions to derive a reduced-model polynomial equation to predict the Y1, Y2 and Y3 for optimized moxifloxacin in situ gelled nanosuspension. Results: Desirability plots showed the effects of X1, X2, and X3 on Y1, Y2 and Y3, respectively. The design space is generated to obtain optimized process parameters viz. chiller temperature (-5 degrees C), HPH pressure 800-900 bar and 8 cycles that resulted in nanosuspension with approximate to 500 nm size, encapsulation efficiency >65% and final formulation temperature <23 degrees C that were necessary to maintain the formulation in a liquid state. Conclusion: Quality by Design (QbD) approach is recently been encouraged by regulatory bodies to improve the quality of the finished product. This approach proved to be a useful tool in the development of robust nanosuspension of highly hydrophilic drugs with improved efficiency. Results indicate that such hybrid gel systems can be used to control the release of SLNs from application site and prolong their action in a sustained manner.