OICC Press Journal of Nanostructure in Chemistry 2193-8865 3 1 (December 2013) 2013 07 26 Preparation and study of vitamin A palmitate microemulsion drug delivery system and investigation of co-surfactant effect 10.1186/2193-8865-3-59 EN Solmaz Maleki Dizaj Faculty of Pharmacy, Tabriz University of Medical Science, Tabriz, IR Student Research Committee, Tabriz University of Medical Science, Tabriz, IR Journal Article 2013 07 26 Abstract The oral route is the main route of drug delivery in many diseases. A major problem in oral oil-soluble drug administration is poor aqueous solubility. One way to deliver oil-soluble drugs is to incorporate the drug into an inert vehicle, such as microemulsions. The purpose of this research was to develop the oil-in-water (o/w) microemulsion areas of pseudo-ternary phase diagrams for a drug delivery system. Our systems consist of sunflower oil + surfactant (Tween 80) + vitamin A palmitate + different co-surfactants + water. Vitamin A palmitate is an oil-soluble drug with poor aqueous solubility. Our goal is to increase its aqueous solubility. The effects of different co-surfactants on the o/w microemulsion region were investigated. The co-surfactants studied were anhydrous glycerol, sucrose, ethanol, and 1-propranol. A titration technique was employed for the preparation of the samples. The phases were identified by visual inspection and polarized microscopy. Samples of the microemulsion area were separated, and pseudo-ternary phase diagram was plotted for them. The system sunflower oil + Tween 80 + sucrose + water+ model drug showed the largest o/w microemulsion region. Consequently, sucrose was selected as the best co-surfactant. Finally, some samples of this system were selected for particle size measurement and stability testing. Results showed that more than 90% of the samples in different temperatures (4°C, 45°C, and room temperature) are stable.