Bemotrizinol-Loaded Nanostructured Lipid Carriers for the Development of Sunscreen Emulsions

The efficacy and safety of organic UV-filters could benefit from their incorporation into lipid nanoparticles because of the ability of such carriers to reflect solar radiations, thus acting synergically as physical sunscreens. In this work, bemotrizinol (BMTZ), a broad-spectrum UV-filter, was loaded into nanostructured lipid carriers (NLC) whose lipid matrix contained different oils to assess the effects of the lipid core composition on the properties of the resulting NLC. Subsequently, the effects of incorporating different concentrations of optimized BMTZ-loaded NLC on the technological properties of O/W emulsions (pH, viscosity, spreadability, occlusion factor, in vitro BMTZ release and skin permeation, in vitro sun protection factor) were assessed. Optimized BMTZ-loaded NLC showed mean size=190.6±9.8 nm, PDI=0.153±0.013, ζ-potential=-10.6±1.7 mV, loading capacity=8% w/w. The incorporation of increasing concentrations of optimized BMTZ-loaded into emulsions provided slight increase of spreadability, lower viscosity and no change of pH, occlusion factor and BMTZ release compared to the control. No BMTZ skin permeation was observed from all formulations. About 20% increase of sun protection factor values was obtained for vehicles containing BMTZ-loaded NLC. Therefore, BMTZ-loaded NLC incorporation into emulsions could be a promising strategy to develop safer and more effective sunscreen formulations.