Q10-loaded NLC versus nanoemulsions: stability, rheology and in vitro skin permeation.

In this study, nanoemulsions (NE) of medium chain triacylglycerols (MCT) and nanostructured lipid carriers (NLC) of cetyl palmiate/MCT were produced to load coenzyme Q(10) (Q(10)) and characterized for their stability before and after incorporation into xanthan gum hydrogels. After storage at 4, 25 and 40 degrees C, the particles remained in the nanosize range for 12 months, with zeta potential higher than |40 mV|. Similar results were found in xanthan gum-based hydrogels containing NE or NLC. The crystallinity index of Q(10)-loaded NLC increased after being incorporated into hydrogels. The Q(10) entrapped in NLC and NE remained higher than 90% at all temperatures for 12 months but dramatically decreased when exposed to light. From the rheological studies, both NLC and NE dispersions possessed pseudoplastic flow having more liquid characteristics, whereas NLC and NE hydrogels exhibited plastic flow with thixothopy, showing more elastic rather than viscous properties. The occurrence of a spatial arrangement of lipid molecules was observed in the matrix of NLC when entrapped into hydrogels. From in vitro permeation studies, it could be stated that the amount of Q(10) released and occlusiveness were major keys to promote the deep penetration of Q(10) into the skin.