DSPE-PEG,Tween80和Brij35对伊文思蓝脂质体包封率和体内分布的影响

目的寻找与DSPE．PEG功能相似的表面活性剂，以增加脂质体的稳定性，改善其体内分布，提高靶向性。方法制备了伊文思蓝脂质体，考察了胆固醇与磷脂的比例对伊文思蓝脂质体包封率的影响；比较了用DSPE-PEG、Tween80和Brij35修饰后的伊文思蓝脂质体包封率和在大鼠体内分布状况的变化。结果伊文思蓝脂质体的包封率最高为25．30％。用DSPE-PEG、Tween80和Brij35修饰后使伊文思蓝脂质体的包封率略有下降，但差别不显著；体内分布实验结果显示：修饰后的脂质体在肝、脾和肾中伊文思蓝的浓度均有不同程度的降低，脑中伊文思蓝的浓度有所提高，而且以Tween80修饰组最显著。结论DSPE-PEG、Trween80和Brij35对伊文思蓝脂质体的包封率影响较小。Brij35对伊文思蓝脂质体的作用与DSPE-PEG相似，能提高脂质体逃避网状内皮系统吞噬的能力；Tween80主要能增加伊文思蓝脂质体在大鼠脑组织中的分布，为脑靶向脂质体的研究提供了有益信息。     

不同表面活性剂对两性霉素B脂质体体内外性质的影响

目的寻找与DSPE-PEG功能相似的表面活性剂修饰两性霉素B脂质体，以增加其在体内的稳定性，改善其体内分布，降低毒副作用。方法用薄膜超声法制备两性霉素B脂质体；比较用DSPE-PEG，Tween 80和Brij 35修饰后两性霉素B脂质体包封率、粒径分布、稳定性及组织分布的变化。结果两性霉素B脂质体的包封率最高为（91.2±1.6）％。修饰后的两性霉素B脂质体包封率提高，粒径减小，稳定性增加，肝、脾和肾中两性霉素B的浓度降低，脑中AmB的浓度提高。结论DSPE-PEG和Brij 35能提高脂质体逃避网状内皮系统吞噬的能力；Tween 80能增加两性霉素B在大鼠脑组织中的分布。     

不同表面活性剂对伊文思蓝脂质体体内外性质的影响

目的　寻找与二硬脂酰磷脂酰乙醇胺 聚乙二醇 (DSPE PEG)功能相似的表面活性剂 ,以增加脂质体的稳定性 ,改善其体内分布 ,提高靶向性。方法　制备伊文思蓝 (EB)脂质体 ,考察胆固醇与磷脂的比例对伊文思蓝脂质体包封率的影响 ;比较用DSPE PEG、吐温 80 (Tween 80 )和苄泽 3 5 (Brij 3 5 )修饰后的EB脂质体的包封率和在大鼠体内组织分布状况的变化。结果　EB脂质体的包封率最高为 2 5 3 0 %。用DSPE PEG、Tween 80和Brij 3 5修饰后使EB脂质体的包封率略有下降 ,但差别不显著 ;体内分布实验结果显示 :修饰后的脂质体在肝、脾和肾中EB的浓度均有不同程度的降低 ,脑中EB的浓度有所提高 ,而且以Tween 80修饰组最显著。结论　DSPE PEG、Tween 80和Brij 3 5对EB脂质体的包封率影响较小。Brij 3 5对EB脂质体的作用与DSPE PEG相似 ,能提高脂质体逃避网状内皮系统吞噬的能力 ;Tween 80主要能增加EB脂质体在大鼠脑组织中的分布 ,为脑靶向脂质体的研究提供了有益信息     

番茄红素脂质体的体外释放及大鼠体内药代动力学和抗氧化功能

利用旋转薄膜-超声法制备了番茄红素脂质体并研究其体外释放，大鼠体内药代动力学和对机体抗氧化能力的影响。用液相色谱法测定大鼠体内的番茄红素含量，所得数据进行3P97程序处理，得到各主要药代动力学参数；配制人工胃液和肠液，比较番茄红素油和番茄红素脂质体的体外释放效果；番茄红素油和番茄红素脂质体灌胃后，用试剂盒测定大鼠血清和肝组织匀浆中的超氧化物歧化酶活性、丙二醛、总抗氧化能力、过氧化氢酶及谷胱甘肽过氧化酶的含量。结果显示，脂质体体外释放呈肠溶性；番茄红素油及番茄红素脂质体的T_max分别为4.45和7.45 h；C_max为0.473和0.654 μg·mL^-1；AUC分别为12.38和21.67 μg·h·mL^-1。抗氧化指标测定结果表明：番茄红素脂质体比番茄红素油显著地提高机体内抗氧化酶的活力，抑制脂质过氧化。     

双配体修饰的阿霉素脂质体靶向于脑胶质瘤的体外研究

目的筛选和优化转铁蛋白、叶酸共同修饰的阿霉素脂质体的处方及制备工艺,以期得到具有良好的脑胶质瘤靶向治疗作用的给药系统。方法采用薄膜分散和硫酸铵梯度法制备阿霉素脂质体。将叶酸连接至二硬脂酸磷脂酰乙醇胺-聚乙二醇2000(DSPE-PEG2000-NH2)得到DSPE-PEG2000-Folic,考察不同磷脂种类、药脂比、水化介质和载药时间,对脂质体粒径、包封率和稳定性的影响,确定脂质体的处方工艺。以大鼠的脑毛细血管内皮细胞(bEnd3)和星形胶质细胞组成体外血脑屏障(blood-brain barrier,BBB),并结合大鼠胶质瘤C6细胞,构建体外模拟胶质瘤靶向治疗的复合BBB模型。考察阿霉素脂质体在bEnd3细胞中的摄取机制和透过BBB的转运速率及对C6细胞的毒性。结果确定了DSPC作为主要磷脂组分,并以120 mmol.L 1的硫酸铵作为水化介质,药脂比为1∶1 5,载药时间选择60 min,成功制备了高包封率和稳定性的双配体脂质体。其在bEnd3细胞中摄取远大于普通脂质体(P<0.05),摄取过程受网格蛋白和小窝内陷介导的细胞内吞作用,并受转铁蛋白和叶酸的影响;同时其在BBB模型中的药物透过速率、及其进一步透过BBB后对下层C6细胞的毒性,均显著高于其他脂质体组。结论转铁蛋白和叶酸共同修饰的阿霉素脂质体具有较好的体外脑胶质瘤靶向治疗作用。     

月桂酸二乙醇酰胺修饰利福喷丁脂质体的制备、性质及肺部给药

目的制备表面活性剂修饰利福喷丁(RIF)脂质体，进行该脂质体水化性能、载药量、释药速度和肺部给药研究。方法采用薄膜超声法制备利福喷丁脂质体，比较月桂酸二乙醇酰胺(LDEA)，Tween 80和azone修饰利福喷丁脂质体的形态、包封率、释药速度和离体猪肺膜透过性，通过纤支镜进行肺部给药研究。结果RIF-LDEA脂质体粒径在15～50 nm，包封率为83.0%，表观透膜系数Kp为44.29；LD₅₀为675 mg·kg^-1。结论LDEA修饰使利福喷丁脂质体的载药量增加1倍、释药速度的可调性强及安全性好。经纤支镜介导灌注给药治疗肺内膜结核的效果显著。     

不同量羧甲基壳聚糖修饰紫杉醇脂质体对大鼠体内药动学的影响

目的:考察不同量羧甲基壳聚糖(CMCT)修饰紫杉醇脂质体后对大鼠体内药动学行为的影响。方法:大鼠尾静脉注射未修饰紫杉醇脂质体,0.1%CMCT修饰紫杉醇脂质体及0.2%CMCT修饰紫杉醇脂质体,血浆处理以炔诺酮为内标,叔丁基甲醚提取。检测波长227 nm,甲醇-水65 35为流动相,ODS-C18柱进行分析。结果:未修饰紫杉醇脂质体,0.1%CMCT修饰紫杉醇脂质体及0.2%CMCT修饰紫杉醇脂质体血浓经时曲线均符合二室模型,t1/2β分别为11.2、15.6、30.6 h,AUC0-1440分别为2541.99、2748.783、451.64 mg.L-1.min。结论:羧甲基壳聚糖修饰后紫杉醇脂质体的大鼠体内药动学行为有明显的改变,消除半衰期和血中的循环时间均有不同程度的延长,AUC增加,且与其用量有一定的相关性。     

伊立替康脂质体的血浆药物含量检测及药动学研究

目的 考察伊立替康脂质体大鼠血浆药物浓度随时间变化趋势和药动学参数,并与伊立替康注射液进行比较,评价伊立替康脂质体药动学特性。方法 大鼠尾静脉注射给予伊立替康脂质体注射液,给药剂量分别为5,10,20 mg·kg^-1,对照组给予伊立替康注射液20 mg·kg^-1。采用HPLC检测大鼠血浆中伊立替康含量。采用DAS 3.0软件,按药动学模块非房室模型计算分析药动学参数。采用SPSS 18.0软件进行药动学参数的统计分析。结果 伊立替康血浆对照品溶液在0.20~100.02 μg·mL^-1内线性良好,r=0.999 3。与伊立替康注射液相比,伊立替康脂质体注射液的血浆达峰浓度C_max显著提高（82倍）,平均滞留时间MRT_（0-t）显著延长（14.6倍）,半衰期t_1/2显著延长（6.5倍）,总伊立替康血浆暴露量极大提高（748.5倍）,经统计学分析均有显著性差异。结论 伊立替康脂质体注射液的药动学参数与伊立替康注射液相比有显著改善,可达到增强药效的目的。     

葡萄糖修饰的不同PEG作为桥联脂质体的体外特性研究

目的 制备用葡萄糖修饰以不同聚合度的PEG作为桥联的脂质体,并考察其体外特性.方法 以香豆素6为荧光探针,用薄膜分散法制备葡萄糖修饰的以PFG400、PEG800、PEG2000作为桥联的载香豆素6脂质体,用激发光散射粒度测定仪测定其粒径;用凝胶柱层析法测定其包封率;在含10%胎牛血清的磷酸盐缓冲液（PBS）中考察其稳定性;以大鼠脑毛细血管内皮细胞（BCECs）为受试细胞,对载香豆素6的不同类型脂质体进行细胞摄取的定量分析.结果 葡萄糖修饰的以PEG400、PEG800、PEG2000作为桥联的脂质体的粒径分别为（81.5±6.3）、（100.0±5.0）、（104.9±8.7）nm,多分散系数（PDI）分别为（0.252±0.016）、（0.265±0.032）、（0.289±0.013）;其包封率均〉80%;在含10%胎牛血清的PBS中具有较好的稳定性;葡萄糖修饰的以PEG800、PEG2000作为桥联的脂质体在BCECs中的细胞摄取率均高于普通脂质体.结论 本研究成功制备了葡萄糖修饰的以PEG400、PEG800、PEG2000作为桥联的脂质体,研究初步显示以PEG800、PEG2000为桥联的脂质体有一定脑靶向潜力.     

3H-紫草素的吸收、组织分布和排泄

本文研究了³H标记的紫草素(shikonin)在小鼠体内的代谢。静脉注射³H紫草素后,血浆消除相半衰期(T 1/2β)为8.79 h,分布容积(V_d)为8.91 L/kg。静脉注射后胆汁及肝中含量最高,肺、脾、肾、心、皮肤中等,睾丸,肌肉、脑含量最低。肌肉注射及灌胃后吸收迅速,血浆浓度达峰时间分别为7.62min和5.78 min。静脉注射后,仅有小部分以原形药从屎及粪排出,大部分以转化形式排出。     

PEGylated liposomes loading palmitoyl prednisolone for prolonged blood concentration of prednisolone

We investigated the pharmacokinetic behavior of palmitoyl prednisolone (Pal-PLS) and its liposomes with L-alpha-distearoylphosphatidylcholine (DSPC) and cholesterol (Chol) with or without L-alpha-distearoylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG 2000) after their intravenous administration in rats. Pal-PLS rapidly disappeared from the systemic circulation and prednisolone (PLS) was regenerated after the administration of DSPC/Chol liposomes. PEGylated liposomes including DSPE-PEG 2000, however, successfully maintained high blood concentrations of Pal-PLS and PLS. The blood profiles of drugs after the administration of liposomal Pal-PLS were analyzed according to a two-compartment model. The larger content of DSPE-PEG 2000 in DSPC/Chol liposomes showed a lower first order elimination rate constant from the central compartment (K(el)) and clearance (CL). The area under the concentration-time curve (AUC) of Pal-PLS and PLS in PEGylated liposomes was larger than DSPC/Chol liposomes. The mean resident time (MRT) of Pal-PLS and PLS was also prolonged by PEGylated liposomes. Although DSPC/Chol liposomes showed a high distribution of Pal-PLS in the liver and spleen, PEGylated liposomes significantly decreased the liver distribution of Pal-PLS. The biliary and urinary excretions of drugs for 240 min after drug administration were less than 1% of the administrated dose in any formulations. In conclusion, PEGylated liposomes, including Pal-PLS, are useful for maintain the PLS concentration in the blood after intravenous administration.     

A targeted liposome delivery system for combretastatin A4: formulation optimization through drug loading and in vitro release studies

Efficient liposomal therapeutics require high drug loading and low leakage. The objective of this study is to develop a targeted liposome delivery system for combretastatin A4 (CA4), a novel antivascular agent, with high loading and stable drug encapsulation. Liposomes composed of hydrogenated soybean phosphatidylcholine (HSPC), cholesterol, and distearoyl phosphoethanolamine-PEG-2000 conjugate (DSPE-PEG) were prepared by the lipid film hydration and extrusion process. Cyclic arginine-glycine-aspartic acid (RGD) peptides with affinity for alphav beta3-integrins overexpressed on tumor vascular endothelial cells were coupled to the distal end of polyethylene glycol (PEG) on the liposomes sterically stabilized with PEG (non-targeted liposomes; LCLs). Effect of lipid concentration, drug-to-lipid ratio, cholesterol, and DSPE-PEG content in the formulation on CA4 loading and its release from the liposomes was studied. Total liposomal CA4 levels obtained increased with increasing lipid concentration in the formulation. As the drug-to-lipid ratio increased from 10:100 to 20:100, total drug in the liposome formulation increased from 1.05+/-0.11 mg/mL to 1.55+/-0.13 mg/mL, respectively. When the drug-to-lipid ratio was further raised to 40:100, the total drug in liposome formulation did not increase, but the amount of free drug increased significantly, thereby decreasing the percent of entrapped drug. Increasing cholesterol content in the formulation decreased drug loading. In vitro drug leakage from the liposomes increased with increase in drug-to-lipid ratio or DSPE-PEG content in the formulation; whereas increasing cholesterol content of the formulation up to 30 mol-percent, decreased CA4 leakage from the liposomes. Ligand coupling to the liposome surface increased drug leakage as a function of ligand density. Optimized liposome formulation with 100 mM lipid concentration, 20:100 drug-to-lipid ratio, 30 mol-percent cholesterol, 4 mol-percent DSPE-PEG, and 1 mol-percent DSPE-PEG-maleimide content yielded 1.77+/-0.14 mg/mL liposomal CA4 with 85.70+/-1.71% of this being entrapped in the liposomes. These liposomes, with measured size of 123.84+/-41.23 nm, released no significant amount of the encapsulated drug over 48 h at 37 degrees C.     

pH-sensitive, serum-stable and long-circulating liposomes as a new drug delivery system

The lack of stability in blood and the short blood circulation time of pH-sensitive liposomes are major drawbacks for their application in-vivo. To develop pH-sensitive, serum-stable and long-circulating liposomes as drug delivery systems, the impact of polyethylene glycol-derived phosphatidylethanolamine (DSPE-PEG) on the properties of pH-sensitive liposomes was investigated. pH-sensitive liposomes were prepared with dioleoylphosphatidylethanolamine (DOPE) and oleic acid (DOPE/oleic acid liposome) or DOPE and 1,2-dipalmitoylsuccinylglycerol (DOPE/DPSG liposome). The inclusion of DSPE-PEG enhanced the serum stability of both DOPE/oleic acid and DOPE/DPSG liposomes, but also shifted the pH-response curve of pH-sensitive liposomes to more acidic regions and reduced the maximum leakage percentage. The impact of DSPE-PEG, however, was much lower in the DOPE/DPSG liposomes than in the DOPE/oleic acid liposomes. In tumour tissue homogenates, where the pH is lower than normal healthy tissues, the pH-sensitive DOPE/DPSG liposomes released the entrapped markers rapidly, in comparison with pH-insensitive dipalmitoylphosphatidylcholine/cholesterol/DSPE-PEG liposomes. Moreover, the release rate was not affected by the content of DSPE-PEG. The blood circulation time of methotrexate incorporated in DOPE/UDPSG liposomes was significantly prolonged with increasing content of DSPE-PEG. Taken together, the liposomes composed of DOPE, DPSG and DSPE-PEG (up to 5%) were pH sensitive, plasma stable and had a long circulation time in the blood. The complete destabilization of the liposomes at tumour tissues suggests that the liposomes might be useful for the targeted delivery of drugs such as anticancer agents.     

The effect of PEG coating on in vitro cytotoxicity and in vivo disposition of topotecan loaded liposomes in rats

Amphoteric drugs encapsulated in PEGylated liposomes may not show superior therapeutic antitumor activity due to increased leakage rate of these drugs in presence of PEG-lipids. In order to investigate the effect of PEG coating on in vitro and in vivo characteristics of topotecan loaded liposomes, an amphoteric anticancer drug, PEGylated and conventional liposomes were prepared by lipid film hydration method. Various properties of the prepared nanoliposomes such as encapsulation efficiency, size, zeta potential, physical stability as well as the chemical stability of lactone form of topotecan, cytotoxicity and topotecan pharmacokinetics were evaluated. In vitro cytotoxic activity was evaluated on murine Lewis lung carcinoma (LLC) and human mammary adenocarcinoma (BT20) cells. Pharmacokinetic was evaluated in Wistar rats after i.v. injection of topotecan, formulated in PBS pH 7.4 or in conventional or in PEGylated liposomes. The conventional liposome (CL) formulation was composed of DSPC/cholesterol/DSPG (molar ratio; 7:7:3), while for PEGylated liposome the composition was DSPC/cholesterol/DSPG/DSPE-PEG(2000) (molar ratio; 7:7:3:1.28). The size of both liposomes was around 100 nm with polydispersity index of about 0.1. In comparison with free drug, liposomal topotecan showed more stability for topotecan lactone form in vitro. Compared to free topotecan, PEGylated and conventional liposomes improved cytotoxic effect of topotecan against the two cancer cell line studied. The results of pharmacokinetic studies in rats showed that both CL and PEGylated liposomal formulations increased the concentration of total topotecan in plasma, however, initial concentration and the values of AUC, MRT and t(1/2 beta) were much higher (P<0.001) for PEGylated liposomal drug than for conventional one or free drug. PEGylated liposome resulted in a 52-fold and 2-fold increases in AUC(0-infinity) compared with that of free topotecan and CL, respectively. These results indicated that PEG modified liposome might be an effective carrier for topotecan.     

Prolonged Blood Circulation of Methotrexate by Modulation of Liposomal Composition

Prolonged circulation by liposomal incorporation has been shown to enhance the therapeutic efficacy of drugs in many cases. The purpose of this study was to investigate whether the prolonged circulation of methotrexate (MTX) can be achieved by modulating the liposomal compositions. Various compositions of liposomes were prepared with 2:1 of phosphatidylcholine (PC) and cholesterol (CH) with or without distearoylphosphatidyl-ethanolamine-N-poly(ethyleneglycol) 2000 (DSPE-PEG). The MTX encapsulation efficiency depended on the type of PC used. It also appeared to increase by inclusion of DSPE-PEG. The size of liposomes decreased by the inclusion of DSPE-PEG. The inclusion of DSPE-PEG lowered the plasma-induced release of MTX from EggPC/CH and DPPC/CH liposomes, suggesting its enhancement effect on the liposomal stability. After intravenous injection to rats, the pharmaockinetics and biodistribution of MTX were significantly changed by liposomal incorporation and also by the composition of liposomes. The total body clearance of MTX incorporated in EggPC/CH, DPPC/CH, EggPC/CH/DSPE-PEG, and DPPC/CH/DSPE-PEG liposomes decreased 4.4-, 14.9-, 24.5-, and 53.1-fold, compared with that of free MTX. The ratio of MTX concentration in blood to liver and spleen after injection of DPPC/CH, EggPC/CH/DSPE-PEG, and DPPC/CH/DSPE-PEG liposomes was 5.4-, 8.5-, and 13.5-fold higher than that of EggPC/CH liposomes. Furthermore, the accumulation of MTX in the kidney, one of the organs in which MTX exhibits its toxicity, was significantly lowered by liposomal incorporation, especially by DSPE-PEG-containing liposomes. Taken together, DPPC/CH/DSPE-PEG liposomes most effectively prolonged the blood circulation, and reduced hepatosplenic and kidney uptake of MTX. DPPC/CH/DSPE-PEG liposomes may have potential as an efficient delivery system for MTX.     

Disposition and tissue distribution of imatinib in a liposome formulation after intravenous bolus dose to mice

Imatinib is an efficacious anticancer drug with a spectrum of potential antitumour applications limited by poor biodistribution at therapeutic concentrations to the tissues of interest. We assess the pharmacokinetic and tissue distribution profile of imatinib in a liposome formulation. Its single dose (6.25 mg x kg(-1)) in a liposome formulation was administered iv to male mice. Imatinib concentration was measured in plasma, spleen, liver, kidney and brain using a HPLC assay. Non-compartmental pharmacokinetic approach was used to assess the disposition parameters. The plasma disposition profile was biphasic with a plateau-like second phase. The AUC(0-->infinity) was 11.24 microg x h x mL(-1), the elimination rate constant (k(el)) was 0.348 h(-1) and the elimination half life (t(1/2)) was 2.0 h. The mean residence time (MRT) was 2.59 h, V(SS) was 1.44 L x kg(-1) and clearance was 0.56 L x h x kg(-1). Liver achieved the highest tissue exposure: CMAX = 18.72 microg x mL(-1); AUC(0-->infinity)= 58.18 microg x h x mL(-1) and longest t(1/2) (4.29 h) and MRT (5.31 h). Kidney and spleen AUC(0-->infinity) were 47.98 microg x h x mL(-1) and 23.46 microg x h x mL(-1), respectively. Half-life was 1.83 h for the kidney and 3.37 h for the spleen. Imatinib penetrated into the brain reaching approximately 1 microg x g(-1). Upon correction by organ blood flow the spleen showed the largest uptake efficiency. Liposomal imatinib presented extensive biodistribution. The drug uptake kinetics showed mechanism differences amongst the tissues. These findings encourage the development of novel imatinib formulations to treat other cancers.