Development and optimization of baicalin-loaded solid lipid nanoparticles prepared by coacervation method using central composite design.

The objective of this study was to design and optimize a novel baicalin-loaded solid lipid nanoparticles (SLNs) carrier system composed of a stearic acid alkaline salt as lipid matrix and prepared as per the coacervation method in which fatty acids precipitated from their sodium salt micelles in the presence of polymeric nonionic surfactants. A two-factor five-level central composite design (CCD) was introduced to perform the experiments. A quadratic polynomial model was generated to predict and evaluate the independent variables with respect to the dependent variables. The composition of optimal formulation was determined as 0.69% (w/v) lipid and 26.64% (w/w) drug/lipid ratio. The results showed that the optimal formulation of baicalin-loaded SLN had entrapment efficiency (EE) of 88.29%, particle size of 347.3 nm and polydispersity index (PDI) of 0.169. The morphology of nanoparticles was found to be nearly spherical in shape by scanning electron microscopy (SEM) observation. The differential scanning calorimetry (DSC) analysis indicated that the drug incorporated into SLN was not in an amorphous form but in a crystalline state. The C(max), MRT, AUMC(0→∞) and AUC(0→∞) values of SLN were approximately 1.6-fold, 1.9-fold, 5.0-fold and 2.6-fold greater than that of reference preparation, respectively.