Optimization of the different phases of the freeze-drying process of solid lipid nanoparticles using experimental designs

In this work, the effect of cryoprotectant type and concentration and freeze-drying process parameters were evaluated to determine an optimal freeze-drying process for celecoxib-loaded solid lipid nanoparticles. Different cryoprotectants were tested at different weight ratios (cryoprotectant:lipid). Trehalose, maltose, and sucrose at a 1:1 wt ratio were selected for further use in optimizing the freeze-drying process through experimental designs to accurately define the freezing, primary, and secondary drying conditions of the freeze-drying process. The optimal freeze-dried solid lipid nanoparticles were subjected to a 6-month stability study at either 4 degrees C or 25 degrees C/ 60% RH, resulting in significant growth when the nanoparticles were stored at 25 degrees C/60% RH. The best results were obtained with trehalose as a cryoprotectant and storage at 4 degrees C. Furthermore, the in vitro release data showed a significantly different release profile before and after optimization of the freeze-drying process, sug-gesting that the optimization of the freeze-drying process affected the quality of the freeze-dried cake. In conclusion, a successful lyophilization process was obtained due to rational cooperation between a good formulation and optimal conditions in the freezing and drying steps. This yielded an acceptable non-collapsed freeze-dried cake with good redispersibility, minimal changes in physicochemical properties, and long-term stability at 4 degrees C.

Automated summary

The study evaluated the effect of cryoprotectant type and concentration and freeze-drying process parameters on celecoxib-loaded solid lipid nanoparticles. Trehalose, maltose, and sucrose at a 1:1 weight ratio were found to be the optimal cryoprotectants for freeze-drying. Storage at 4 degrees C with trehalose as a cryoprotectant yielded the best results. The optimized freeze-drying process affected the quality and in vitro release profile of the freeze-dried cake.