Sterilization and freeze-drying of drug-free and drug-loaded solid lipid nanoparticles

Solid lipid nanoparticles (SLN) have been prepared from three oil-in-water microemulsions, whose internal phase was constituted of different lipid matrices. The dispersion media were two aqueous solution of trehalose and Pluronic F68 at 2% besides distilled water. SLN were sterilized by autoclaving, were stable during sterilization and maintained a spherical shape and narrow size distribution as confirmed by TEM analysis. SLN dispersions in water did not present nanoparticles larger than 1 mu m after storage at 4 degrees C for 1 year; they were freeze-dried after sterilization to b obtain dry products. Diazepam was used as model drug to incorporate into SLN, where it was shown by calorimetric analysis to be in amorphous form. (C) 1997 Elsevier Science B.V.