Optimization of nanostructured lipid carriers for topical delivery of nimesulide using Box-Behnken design approach

Objective: The aim of the present study was to develop and optimize topically applied nimesulideloaded nanostructured lipid carriers. Materials and methods: Box-Behnken experimental design was applied for optimization of nanostructured lipid carriers. The independent variables were ratio of stearic acid: oleic acid (X-1), poloxamer 188 concentration (X-2) and lecithin concentration (X-3) while particle size (Y-1) and entrapment efficiency (Y-2) were the chosen responses. Further, skin penetration study, in vitro release, confocal laser scanning microscopy and stability study were also performed. Results and discussion: The optimized nanostructured lipid carriers of nimesulide provide reasonable particle size, flux, and entrapment efficiency. Optimized formulation (F9) with mean particle size of 214.4 +/- 11 nm showed 89.4 +/- 3.40% entrapment efficiency and achieved mean flux 2.66 +/- 0.09 mu g/cm2/h. In vitro release study showed prolonged drug release from the optimized formulation following Higuchi release kinetics with R-2 value of 0.984. Confocal laser scanning microscopy revealed an enhanced penetration of Rhodamine B-loaded nanostructured lipid carriers to the deeper layers of the skin. The stability study confirmed that the optimized formulation was considerably stable at refrigerator temperature as compared to room temperature. Conclusion: Our results concluded that nanostructured lipid carriers are an efficient carrier for topical delivery of nimesulide.