| 研究実績の概要 |
In this year, the mechanisms of calcein leakage established in the previous year equally influenced the entrapment yields of 5-fluorouracil (5-FU) and metformin hydrochloride (MH), the antineoplatic and antihyperglycemic agents, respectively. For Tween 80 stabilized vesicle suspension, the entrapment yields of 5-FU and MH increased with decrease in the surfactant concentration, and then decreased at lower surfactant concentration. This trend was attributed to the combined effects of bilayer destabilization/solubilization and reversed-micellar transport. The entrapment yields of the drugs were found to be higher than those reported in the literature. However, the entrapment yield of calcein was remarkably higher than those of the drugs. The difference was explained in relation to their differing molecular weights and relative hydrophobicity. The vesicle suspension was equally found to be stable for about one month of storage at 4 °C. During storage, the entrapment yield decreased slightly and was considered to be due to minimal leakage of the drugs from the internal water phase of the vesicle to the continuous phase through the lipid bilayers. From these studies, the multiple emulsion and solvent evaporation integrated method offers great potentials for the formulation of lipid vesicles with controlled size and high entrapment yields of hydrophilic bioactive molecules, and would find industrial applications in pharmaceuticals, cosmetics, food, and other related fields.
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