Preparation and Safety Evaluation of Topical Simvastatin Loaded NLCs for Vitiligo

Purpose: Vitiligo is a long-term common autoimmune disease in which growing patches of skin lose their color. There is no FDA-approved treatment for vitiligo. However, recent studies have demonstrated an immunosuppressive effect on vitiligo lesions in mouse models by simvastatin. A topical formulation was prepared containing simvastatin-loaded nano lipid carriers (simNLCs) for vitiligo treatment followed by evaluating their physicochemical characteristics and clinical safety. Methods: Both the lipid phase and the aqueous phase were heated to 75°C separately, and then simvastatin was dispersed in the lipid phase added to the aqueous phase. The mixture was homogenized for 1 minute, then for Nanostructured Lipid Carriers (NLC) formation, the emulsion was sonicated using a probe sonicator. The simNLCs produced were evaluated for drug entrapment, particle size and morphology, zeta potential, polydispersity index, viscosity, drug content, in vitro drug release, in vivo skin safety test, and long-term stability studies. Results: Dynamic light scattering, transmission electron microscopy and differential scanning calorimetry techniques proved the formation of a stable formulation containing spherical particles with nanoscale size. The drug entrapment efficiency and the drug-loading capacity were determined to be 99.27% and 3.9%, respectively. Human safety results indicated that adding simvastatin to lipid nanoparticles did not cause any changes to skin biophysical parameters. Conclusion: The preparation method of simNLC developed in this study is a suitable method, and the nanoparticles fabricated were safe with acceptable long-term stability and drug entrapment.