Lipid nanoparticles as carrier for octyl-methoxycinnamate: in vitro percutaneous absorption and photostability studies

The aim of the present study was the evaluation of lipid nanoparticles (solidlipid nanoparticles, SLN, and nanostructured lipid carriers, NLC) as potential carriers foroctyl-methoxycinnamate (OMC). The release pattern of OMC from SLN and NLC was evaluatedin vitro, determining its percutaneous absorption through excised human skin. Additionalin vitro studies were performed in order to evaluate, after UVA radiation treatment, the spectralstability of OMC-loaded lipid nanoparticles. From the obtained results, ultrasonicationmethod yielded both SLN and NLC in the nanometer range with a high active loading and aparticle shape close to spherical. Differential scanning calorimetry data pointed out the keyrole of the inner oil phase of NLC in stabilizing the particle architecture and in increasing thesolubility of OMC as compared with SLN. In vitro results showed that OMC, when incorporatedin viscosized NLC dispersions (OMC–NLC), exhibited a lower flux with respect to viscosizedSLN dispersions (OMC–SLN) and two reference formulations: a microemulsion (OMC-ME)and a hydroalcoholic gel (OMC-GEL). Photostability studies revealed that viscosized NLC dispersionswere the most efficient at preserving OMC from ultraviolet-mediated photodegradation.