| 5-Fluorouracil (5-Fu), a pyrimidine analogue with antimetabolism, is widely used as an chemotherapy in cancer because of its strong lethal effect on proliferating cells. 5-Fu is a kind of hypertoxic drug with bad selectivity of distribution in the body, which may lead to severe adverse effects. 5-Fu administered in oral has a low bioavailability because of its bad absorption in gastrointestinal tract. The half life of 5-Fu is comparatively short so that it should be frequently administered which may cause higher toxicity. In light of the above, microemulsion is used as the drug delivery system for 5-Fu to overcome the above disadvantages and to improve the therapeutic effect of 5-Fu.Pseudo-ternary phase diagrams were applied to select a good formulation and IPM/ODO-L/EtOH/5-Fu-aqueous-solution (mass ratio: IPM:ODO-L:EtOH: 5-Fu-aqueous-solution = 55:10:20:15) was selected as the drug delivery system for 5-Fluorouracil. The 5-Fu microemulsion with optimized formulation had higher loading rate, less surfactants and outstanding physical stability. A convenient assay method of content of 5-Fu microemulsion was established by ultraviolet spectrophotometry and this method had good accuracy and precision. Stability tests demonstrated that appearance, structral type, physico-chemical property parameters and content of 5-Fu microemulsion all had good stability at room temperature in 1 month. On the basis of results of release test, the conclusion that 5-Fu microemulsion was a sustained–release preparation with trait of first order kinetics were made. The absorption of 5-Fu microemulsion in rat intestine was studied by using reverted gut sac method and the results showed that the middle and lower segments of rat intestine were the best sbsorption site for 5-Fu microemulsion and the absorption was remarkably improved.In conclusion, 5-Fu microemulsion which has lower toxicity, good stability, sustained-release trait and better absorption in oral is prepared.
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