全缘千里光碱脂质体包封率测定方法的研究

 目的建立全缘千里光碱(integerrimine,INT)脂质体包封率测定方法。方法尝试以葡聚糖凝胶柱分离法与离心沉淀-离心超滤法测定INT脂质体的包封率,考察了第一种方法中游离药物柱回收率、游离药物和脂质体的分离度,考察了第二种方法中超滤膜对游离药物的吸附、滤出液中有无脂质体以及稀释对包封率测定结果的影响,并以第二种方法测定了空白脂质体与药物水溶液混合制得脂质体的包封率。结果葡聚糖凝胶柱分离法不能实现药物与脂质体的完全分离,超滤膜对INT溶液浓度基本无影响,离心沉淀可实现脂质体与外水相两部分质量的准确分离。离心-超滤法测定中样品稀释1倍使脂质体包封率降低约50%。结论葡聚糖凝胶柱分离法不适于INT脂质体的包封率测定,离心-超滤法可高效、准确、方便地测定INT脂质体包封率;INT与脂质双分子层有一定的亲和力,但在其中的滞留性较差。

Study on Determination of Entrapment Efficiency of Integerrimine Liposomes

OBJECTIVE To develop a method for determining the entrapment efficiency of integerrimine (INT) liposomes. METHODS Sephadex gel filtration and centrifugation sedimentation combined with centrifugation ultrafiltration were tried to determine the entrapment efficiency of integerrimine liposomes. For the first method,the recovery of free INT from the gel column,the resolution between free drug and liposomes was investigated. For the second method,the adsorption of INT to ultrafiltration membrane,the existence of liposomes in the filtrate of ultrafiltration and the effect of dilution on the determination were examined. The entrapment efficiency of the liposomes prepared by direct drug loading (dissolving INT in the dry film forming liquid) and passive drug loading (mixing blank liposome suspension with INT aqueous solution) was determined by the second method respectively. RESULTS Sephadex gel filtration didn't realize the complete separation between free drug and liposomes,although it had good free drug recovery from the column. The rate of INT adsorption to ultrafiltration membrane was very low (<7%). The weight of liposomes and exterior aqueous phase were separated by centrifugation sedimentation. There was no liposome in the filtrate of ultrafiltration. Diluting the liposome suspension with equal volume of hydration liquid decreased the entrapment efficiencies by 50% or so.The entrapment efficiencies of the liposomes prepared by direct drug loading and passive drug loading were 46.75% and 40.88%,respectively. CONCLUSION Centrifugation sedimentation combined with centrifugation ultrafiltration is able to determine the entrapment efficiency of INT liposomes efficiently,accurately and conveniently,while sephadex gel filtration is not able to do it. The retention of INT in the lipid bilayers is very poor,although it has considerable affinity to the lipid bilayers.