Yu B G, Okano T, Kataoka K, Kwon G
Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Canada.
J Control Release. 1998 Apr 30;53(1-3):131-6. doi: 10.1016/s0168-3659(97)00245-9.
Polymeric micelles may serve as nanoscopic, long-circulating carriers of hydrophobic drugs. In this study, we have researched the solubilization of amphotericin B (AmB), an antifungal drug, by micelles of poly(ethylene oxide)-block-poly(beta benzyl-L-aspartate) (PEO-PBLA), the properties of the AmB-loaded PEO-PBLA micelles and the resultant haemolytic activity of AmB. AmB loading takes place during self assembly of PEO-PBLA micelles, and this occurs through a dialysis procedure as an alkaline aqueous solution replaces the selective solvent for the polymer and the drug. In this way, AmB reaches levels of 57 to 141 microg/ml, corresponding to a loading efficiency of 27-30% (loaded AmB/initial amount of AmB). The molar ratio of AmB to PEO-PBLA is 0.40 to 1.0. Pictures by transmission electron microscopy reveal spherical AmB-loaded PEO-PBLA micelles with a mean diameter of 25.8+/-4.2 nm. AmB-loaded PEO-PBLA micelles are nonhaemolytic at an AmB level of 10 microg/ml as assessed by release of haemoglobin, measured by UV-Vis spectroscopy. AmB as Fungizone, its standard formulation, completely lyses red blood cells at a level of 3.0 microg/ml in 30 min. In contrast, there is no haemolysis at 5.5 h for AmB-loaded PEO-PBLA micelles at 3.0 microg/ml of AmB, indicating the gradual release of AmB from PEO-PBLA micelles. PEO-PBLA itself is nonhaemolytic even at a level of 0.70 mg/ml. Most amphiphiles, e.g. sodium deoxycholate, present in Fungizone, are haemolytic. Finally, AmB-loaded PEO-PBLA micelles can be freeze-dried and easily reconstituted in water. Afterwards, AmB is present in the intact PEO-PBLA micelles and remains nonhaemolytic.
聚合物胶束可作为疏水性药物的纳米级、长循环载体。在本研究中，我们研究了聚环氧乙烷-嵌段-聚（β-苄基-L-天冬氨酸）（PEO-PBLA）胶束对抗真菌药物两性霉素B（AmB）的增溶作用、负载AmB的PEO-PBLA胶束的性质以及由此产生的AmB的溶血活性。AmB的负载发生在PEO-PBLA胶束的自组装过程中，这是通过透析程序实现的，即碱性水溶液取代聚合物和药物的选择性溶剂。通过这种方式，AmB的含量达到57至141微克/毫升，对应负载效率为27 - 30%（负载的AmB/初始AmB量）。AmB与PEO-PBLA的摩尔比为0.40至1.0。透射电子显微镜拍摄的图片显示，负载AmB的PEO-PBLA胶束呈球形，平均直径为25.8±4.2纳米。通过紫外-可见光谱法测量血红蛋白释放量评估，在AmB浓度为10微克/毫升时，负载AmB的PEO-PBLA胶束无溶血现象。作为标准制剂的两性霉素B注射剂（Fungizone）中的AmB，在浓度为3.0微克/毫升时，30分钟内可使红细胞完全溶解。相比之下，在AmB浓度为3.0微克/毫升时，负载AmB的PEO-PBLA胶束在5.5小时内无溶血现象，这表明AmB从PEO-PBLA胶束中逐渐释放。即使在浓度为0.70毫克/毫升时，PEO-PBLA本身也无溶血现象。Fungizone中存在的大多数两亲性物质，如脱氧胆酸钠，都具有溶血作用。最后，负载AmB的PEO-PBLA胶束可以冻干并很容易地在水中重构。之后，AmB存在于完整的PEO-PBLA胶束中，并且仍然无溶血现象。
