10.22376/ijpbs.2019.10.1.p1-12 Volume 7 Issue 1 2016 (January - March) Tizanidine hydrochloride (TIZ) is a skeletal muscle relaxant which is used in the treatment of multiple sclerosis. The aim of this study was to prepare and optimize TIZ nanoparticles using 3 lessThan sup greaterThan 2 lessThan /sup greaterThan factorial design. The polymer amount (X lessThan sub greaterThan 1 lessThan /sub greaterThan ) and stabilizer concentration (X lessThan sub greaterThan 2 lessThan /sub greaterThan ) were selected as independent variables and their joint effects on the dependent variables viz. the size, the entrapment efficiency and the zeta potential of nanoparticles were studied. Design-Expert®8.0 software was used as a statistical tool to optimize the formulation design and investigate the effects of the formulation variables. A full model quadratic equation was obtained from multiple regression analysis. 3D surface and interaction plots were employed to graphically represent the effects of independent variables polymer amount (X lessThan sub greaterThan 1 lessThan /sub greaterThan ) and stabilizer concentration(X lessThan sub greaterThan 2 lessThan /sub greaterThan ) on the evaluation parameters size, entrapment efficiency and zeta potential of nanoparticles. GUPTA RITU AND BAJPAI MEENAKSHI Tizanidine hydrochloride (TIZ), 32 Factorial Design, Polymer amount (X1), Stabilizer concentration (X2) 161-173