Cetyl palmitate-based NLC for topical delivery of Coenzyme Q 10 – Development, physicochemical characterization and in vitro release studies

Abstract

In the present study, nanostructured lipid carriers (NLC) composed of cetyl palmitate with various amounts of caprylic/capric triacylglycerols (as liquid lipid) were prepared and Coenzyme Q 10 (Q 10) has been incorporated in such carriers due to its high lipophilic character. A nanoemulsion composed solely of liquid lipid was prepared for comparison studies. By photon correlation spectroscopy a mean particle size in the range of 180–240 nm with a narrow polydispersity index (PI) lower than 0.2 was obtained for all developed formulations. The entrapment efficiency was 100% in all cases. The increase of oil loading did not affect the mean particle size of NLC formulations. NLC and nanoemulsion, stabilized by the same emulsifier, showed zeta potential values in the range −40/−50 mV providing a good physical stability of the formulations. Scanning electron microscopy studies revealed NLC of disc-like shape. With respect to lipid polymorphism, a decrease in the ordered structure of NLC was observed with the increase of both oil and Q 10 loadings, allowing therefore high accommodation for Q 10 within the NLC. Using static Franz diffusion cells, the in vitro release studies demonstrated that Q 10-loaded NLC possessed a biphasic release pattern, in comparison to Q 10-loaded nanoemulsions comprising similar composition of which a nearly constant release was observed. The NLC release patterns were defined by an initial fast release in comparison to the release of NE followed by a prolonged release, which was dependent on the oil content.