Preparation and Formulation Optimization of Loaded Celastrol Nanostructure Lipid Carriers for Topical Ocular Application

Objective: The central composite design-response surface methodology (CCD-RSM) was used to optimize the application of tricorne nanostructured lipid carrier (CEL-NLC) in the local application of eyes. Methods: The lipid with the best solubility was screened out by determining the solubility of celastrol in different lipids. CEL-NLC was prepared by microemulsion technique. Quality of solid lipid (X1), quality of liquid lipid (X2), surfactant/cosurfactant (X3) as objects of investigation, while particle size (Y1), encapsulation efficiency (Y2) and drug loadings rate (Y3) as dependent variables, the optimal prescription was obtained by CCD-RSM and verified subsequently. Results: The best prescription of CEL-NLC was Celastrol 0.04 g, palmitic acid 0.09 g, oleic acid 0.18g, tween-80 4.34 g and Glycerine 2.16 g. The encapsulation efficiency was (75.28 ± 3.44)%; the drug loading rate was (0.45 ± 0.02)%; the particle size was (18.66 ± 2.63) nm. The PDI was 0.39 ± 0.03. The deviation between the measured and predicted values was less than 5%. Conclusion: The optimized CEL-NLC obtained by CCD-RSM has high encapsulation efficiency, small particle size and good stability, which can be further used in the follow-up study of local application of Celastrol in eyes.