Characterization and Stability of Vitamin A Palmitate Microemulsions Composed of Isopropyl Palmitate, Water and Polyoxyethylene-10-Oleyl EtherP. Boonme* and V. B. Junyaprasert
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The systems composed of isopropyl palmitate (IPP) as oil phase, water as aqueous phase and polyoxyethylene-10-oleyl ether (POE-10-OE) as nonionic surfactant were investigated. The results indicated that microemulsion region of IPP/water/POE-10-OE was 13.69% of total area of a ternary phase diagram. Two microemulsion formulations as representatives of low and high surfactant concentrations were selected to be incorporated with vitamin A palmitate (VA). The systems were clear yellowish liquids and no birefringence was observed under cross-polarized light microscopy. They were found to be micreomulsions of water-in-oil (w/o) type. Their rheological properties showed low viscosity with Newtonian flow behavior. After loaded, VA-loaded microemulsions did not change the characteristics of their blank counterparts. Regarding stability, the VA-loaded microemulsions were physically stable but chemically unstable after storage at room temperature for 28 days.
Keyword:
Microemulsions, Vitamin A palmitate, Characterization, Stability
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