Formulation and evaluation of retinyl palmitate and vitamin E nanoemulsion for skin care

Background: Improving and maintaining the skin integrity and health are the most essential targets in long-term care. The aim of this study is to formulate a serum of retinyl palmitate (RP) and vitamin E (VE) as nanoemulsion (NE) for achieving healthy skin. Methods: The solubility of RP and VE was studied in different oils. The NEs were prepared using oil, water, and different surfactant-co-surfactant mixtures, and then the medicated nanoemulsion was prepared by addition of 0.5% RP and VE to the oil phase, and vitamin C as an antioxidant to the aqueous phase with different preservatives. The prepared NE was characterized in terms of particle size, charge, rheology, diffusion, and irritation to the skin. Results and conclusion: The data showed that the highest solubility of both RP and VE was in safflower oil. Tween 20, Ceteareth 20 with ethanol, PEG 200, and cremophor RH40. This combination was able to produce NE with good integrity and acceptable particle size. The prepared formulations gave particle size of 60-70 nm and showed Newtonian flow. Irritation tests on rats showed that the formula was safe to be applied on the skin with no signs of irritation up to 72 hours. A preliminary stability study at room temperature showed good stability up to 6 weeks. In conclusion, RP and VE could be formulated successfully as NE with good stability and physical characteristics.