Topical delivery of nanostructured lipid carriers loaded with lipophilic active compounds on a 3D reconstructed human epidermis model

Pinto, Fátima; Fonseca, Luis; Souza, Sofia; Oliva, Abel; Barros, Dragana

http://hdl.handle.net/10400.18/7050

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Abstract(s)

Lipid nanocarriers refer to a wide group of drug delivery systems that are well-known as effective carriers for lipophilic and hydrophilic active compounds and that can be easily integrated into dermal formulations. Nanostructured lipid carriers (NLCs) belong to the wide group of lipid nanocarriers, representing an alternative – e.g. to liposomes, emulsions and polymeric nanoparticles. Usually, NLCs present a spherical shape with mean diameters ranging between 50 and 500 nm and are composed by an unstructured solid lipid matrix consisting on a mixture of liquid and solid lipids, stabilized by a surfactant or a mixture of surfactants dispersed in an aqueous phase. New optimized NLCs formulations loaded with retinyl palmitate (RP) and α-tocopherol (TOC) were evaluated regarding their topical distribution and efficacy on a 3D model of in vitro reconstructed human epidermis (RHE). NLCs were produced using sunflower oil and myristic acid as liquid and solid lipids, respectively and RP and TOC as lipophilic model compounds. Also, the fluorescent dye DiO was incorporated along with TOC, resulting in a TOC-DiO-NLCs formulation to enable a qualitative characterization on in vitro absorption studies. Physicochemical properties of empty NLCs, RP-NLCs and TOC-DiO-NLCs were characterized, as well as their surface morphology and internal structure. In vitro absorption studies were performed on the RHE model in customized Franz diffusion cells and were quantitatively and qualitatively characterized. The cytotoxicity of optimized NLCs formulations was evaluated through the in vitro skin irritation test on the RHE model. All characterized NLCs presented appropriate physicochemical properties for dermal formulations and an efficient distribution and release profile of active compounds across the reconstructed skin membrane. In vitro skin irritation tests demonstrated that the optimized NLCs formulations were no cytotoxic.