Sustained release formulations often face the challenge of finding the right combination of formulation variables that will produce a product with optimum properties. Optimization becomes even more important when the formulation is a sustained-release dosage form, since many often-interdependent factors can affect the release rate. In this study, we have investigated the effect of formulation variables on several responses. Subsequently, response surface methodology was applied to optimize the formulation after constructing a desirability function that simultaneously combines all the four responses. Formulations of loxoprofen-loaded sustained release microspheres were prepared by solvent evaporation technique and optimized using response surface methodology by fitting a second-order model to the response data. This book provides a detailed discussion on chemometric procedure for the optimization of formulation variables, development of regression models and global optimization of response variables to design quality formulation. This work could form a reference material to those aspiring to pursue research in the design, development and optimization of microspheres.