Statistical optimization of dithranol-loaded solid lipid nanoparticles using factorial design

this study describes a 32 full factorial experimental design to optimize the formulation of dithranol (dth) loaded solid lipid nanoparticles (sln) by the pre-emulsion ultrasonication method. the variables drug: lipid ratio and sonication time were studied at three levels and arranged in a 32 factorial design to study the influence on the response variables particle size and % entrapment efficiency (%ee). from the statistical analysis of data polynomial equations were generated. the particle size and %ee for the 9 batches (r1 to r9) showed a wide variation of 219-348 nm and 51.33- 71.80 %, respectively. the physical characteristics of dth-loaded sln were evaluated using a particle size analyzer, differential scanning calorimetry and x-ray diffraction. the results of the optimized formulation showed an average particle size of 219 nm and entrapment efficiency of 69.88 %. ex-vivo drug penetration using rat skin showed about a 2-fold increase in localization of dth in skin as compared to the marketed preparation of dth.