盐酸表阿霉素长循环脂质体的制备及性质研究

Studies on Preparation and Properties of Epirubicin Hydrochloride Long Circulating Liposome

采用主动载药技术制备盐酸表阿霉素脂质体,用甲氧基聚乙二醇2000-二硬脂酰磷脂酰乙醇胺(PEG2000-DSPE)对其进行修饰制备表阿霉素长循环脂质体,以降低药物的毒性,提高药物对肿瘤部位的被动靶向性。并对处方工艺进行优化,考察其体外释放。以包封率为指标采用乙醇注入法结合硫酸铵梯度法制备表阿霉素普通脂质体和长循环脂质体,采用正交设计优化处方,激光粒度分析仪测定粒径及分布,电位仪测定Zeta电位,应用微柱离心法测定脂质体的包封率;以累积释药百分率为指标,通过方程拟合释药曲线,考察制剂的体外释药特性。通过正交试验设计优化确立普通脂质体的处方为大豆磷脂浓度为2.5%,药物磷脂比为1∶12.5,磷脂胆固醇比例为4∶1,硫酸铵浓度为200 mmol/L,载药孵育温度为50℃,载药时间为30 min。采用与普通脂质体相同的工艺及处方制备表阿霉素长循环脂质体,其中PEG2000-DSPE摩尔比为4%。优化处方制得的两种脂质体外观为均一桔红色半透明乳状液,平均粒径分别为144 nm和126 nm,Zeta电位分别为-16.5 mv和-35.3 mv,用微柱离心法测得包封率分别为94.30%和97.84%。采用透析法对普通脂质体和长循环脂质体进行了体外释放研究,24 h的累计释放度均分别为38.15%和24.65%,长循环脂质体释放比普通脂质体缓慢。长循环脂质体体外释放符合Higuchi方程Q=0.056 4 t1/2-0.032 2(r=0.971 9)。本实验获得了较理想的盐酸表阿霉素长循环脂质体,其体外释放特性符合缓释制剂特征。

The active loading method was adopted to prepare conventional epirubicin hydrochloride liposome and the conventional liposome was modified into long circulating liposome by adding methoxy polyethylene glycol 2000-distearoyl phosphatidyl ethano- lamineb （PEG2000-DSPE）, to reduce the drug toxicity and improve the tumor targeting effect. To optimize the formulation by orthog- onal experiment design,and to evaluate its in vitro release behavior. Conventional epirubicin hydrochloride liposome and epirubicin hydrochloride long circulating liposome were prepared by ammonium sulfate method combined with ethanol-injection method. The particle size distribution of conventional epirubicin hydrochloride liposome and epirubicin hydrochloride long circulating liposome was examined with laser particle size analyzer. The zeta potential of conventional epirubicin hydrochloride liposome and epirubiein hydro- chloride long circulating liposome were examined by potential instrument. The encapsulation efficiency of conventional epirubicin hydrochloride liposome and epirubiein hydroehloride long circulating liposome were examined by micro-column centrifuge method. The property of their release in vitro was investigated, based on the measure of accumulated release ratio and the fitting of release curve. Through orthogonal design, the optimized preparation process and formula were as follows ： the concentration of soybean phos- pholipids was 2.5 %, the ratio of drug to lipid was 1 ： 12.5, while the ratio of cholesterol to lipid was 1 ： 4 ; the concentration of ammonium sulfate was 200 mmol/L and the incubation condition was 50 ℃ 30 min. The long circulating liposome was prepared according to the formula of conventional liposome except for adding 4% molar ratio of methoxy polyethylene glycol 2000-distearoyl phosphatidyl ethanolamine. The optimized result showed that the two liposomes were homogenous reddish red liposome. The mean diameter of conventional liposome and long circulating liposome were 144 urn and 126 nm respectively ,while zeta potential of the two liposomes was - 16.5 mv and - 35.3 mv respectively. The entrapment efficiency of the two liposomes were 94.30% and 97.84% respectively,in vitro release was investigated by the dialysis method and the cumulative release rate of the two liposome was 38.16% and 24. 65% respectively in 24 h. The long circulating liposome showed slower release profile. The epirubicin hydrochloride long circulating liposome in vitro release was in line with Higuchi equation Q = 0.056 4 t1/2 -0. 032 2 （r = 0. 971 9 ）. This formulation method obtained ideal epirubicin hydrochloride long circulating liposome, and its in vitro release characteristics was in line with properties of sustained-released preparation.