Formulation and in vitro evaluation of zinc oxide and octocrylene in solid lipid nanoparticles, microemulsions and cream systems

An ultimate sunscreen should be water resistant and have a broad-spectrum protection along the entire range of the UVA and UVB spectra. UVC radiation is less of an issue, since it doesn?t reach the earth?s surface due to its absorption by the ozone layer in the atmosphere. Efficacy of sunscreens depends upon their UVabsorption, concentration, formulation and the ability to withstand swimming or sweating. UV filters have been traditionally divided into chemical absorbers and physical blockers depending on their mechanism of action. In this study, one of the most important physical blocker, zinc oxide, and chemical absorber, octocrylene, were used in three different delivery systems. Solid lipid nanoparticles, which show a UV-blocking potential and act as physical sunscreens were combined with UV filters in order to achieve improved photoprotection. Microemulsion and cream emulsions were prepared in water-in-oil form to prevent the effect of water. Determination of octocrylene in the formulations was performed by high pressure liquid chromatography. On the other hand, inductively coupled plasma - optical emission spectroscopy was used for zinc oxide. Stability tests were carried out at 25ºC, 4ºC and 40ºC conditions and analyses were performed on 15th, 30th, 90th, 180th and 360th days. UV protection abilities of the three formulations were investigated and compared using in vitro Transpore? Test method. Key Words: Solid Lipid Nanoparticles (SLN) Microemülsion Cream TransporeTM Test Zinc Oxide Octocrylene