依托泊苷长循环脂质体工艺处方设计与优化的研究

目的优化依托泊苷长循环脂质体的制备处方及工艺。方法以两亲性聚乙二醇一二硬脂酰磷脂乙醇胺为修饰体，采用薄膜超声．挤压法制备空白长循环脂质体；铵离子梯度法包封依托泊苷，制备依托泊苷长循环脂质体。以包封率为考察指标，采用正交设计法优化依托泊苷长循环脂质体的制备处方及工艺。结果优化后的依托泊苷长循环脂质体的工艺和处方：药脂比例为1：5tool·mol^-1、胆固醇与磷脂比例为0．3：1（W／w）、硫酸铵离子浓度为200mmol·L%^-1、包封温度为55℃。长循环脂质体平均粒径均小于1μm，药物平均包封率86．45％。结论该方法包封率高、粒径小且分布较窄，简便易行。     

尼莫地平脂质体的制备与理化性质研究

［摘要］目的制备尼莫地平脂质体并考察其理化性质。方法采用单因素考察及正交优化实验,对尼莫地平脂质体的处方组成进行了筛选,对制备工艺进行了优化,同时对尼莫地平脂质体包封率、粒子粒径、磷脂氧化率等进行了测定。结果尼莫地平脂质体最佳处方中磷脂与胆固醇之比为1：4,二硬脂酰磷脂酰甘油与磷脂和胆固醇混合物之比为1：10,主药与总脂质量之比为1：40。尼莫地平脂质体平均粒径为145.2 nm,包封率为97.6%。结论制备的尼莫地平脂质体包封率较高,稳定性良好,符合临床用药要求。     

乳香挥发油脂质体的制备及质量评价

目的研制乳香挥发油脂质体并进行质量评价。方法采用正交设计法进行试验,以包封率为指标筛选处方,并对脂质体形态、粒径大小与分布、Zeta电位及包封率等质量指标进行评价。结果最佳处方为A3B3C2,即：胆固醇与磷脂的重量比为1：6、药脂重量比为1：6、制备温度为60℃。质量评价结果表明脂质体圆整均匀,平均粒径、Zeta电位和包封率分别为150nm、-39．5mV和（87．7％±1．23％）。结论乳香挥发油脂质体的制备工艺方便、科学,各项质量指标良好。     

Box-Behnken效应面法优化制备主动载药盐酸小檗碱脂质体

目的采用Box-Behnken效应面法筛选最佳处方,制备盐酸小檗碱脂质体。方法采用薄膜分散-p H梯度法制备脂质体,分别以磷脂与胆固醇质量比、脂药质量比、外水相p H值、孵化温度为考察对象,以包封率、粒径和载药量为评价指标,采用4因素3水平Box-Behnken效应面设计法筛选盐酸小檗碱脂质体的最佳处方。采用阳离子交换树脂微柱离心法测定包封率,动态激光散射法测定脂质体的粒径,并采用透射电镜观察制得的脂质体形态。结果最优处方工艺条件为磷脂与胆固醇质量比为3.38∶1,脂药质量比为22∶1,外水相p H为6.88,孵化温度为59℃。以最优处方制备的盐酸小檗碱脂质体平均粒径、包封率、载药量与预测值偏差较小。结论采用Box-Behnken效应面法优化盐酸小檗碱脂质体工艺处方是可行的。     

环孢素脂质体的制备工艺与质量评价

目的制备环孢素脂质体并进行质量评价。方法用薄膜一超声分散法制备环孢素脂质体,以包封率为评价指标,正交设计法优化处方和工艺,用HPLC法测定环孢素的含量,并观察其形态、粒径和稳定性。结果用混合磷脂制备环孢素脂质体的最优处方是磷脂和胆固醇的质量比为4：1,磷脂在水化介质中的浓度为3％,药物和磷脂的质量比为1：40,水化介质为pH=7．4的磷酸盐缓冲液;最佳的工艺条件为水化温度45℃,水化时间30min,搅拌时间10min,超声时间2h。按该处方工艺制备的脂质体包封率为97．84％,98．2％的粒径为（32．65±5．46）nm。在4℃冰箱存放5个月后形态和粒径无明显变化,渗漏率为4．55％。结论制备的环孢素脂质体包封率高、粒径小、稳定性好。     

尼莫地平鼻用冻干脂质体的制备及大鼠鼻黏膜吸收

采用改良乙醇注入法制备了尼莫地平脂质体，运用均匀设计试验优化了脂质体处方，并考察了冷冻干燥工艺与处方因素对其冻干脂质体性质的影响。在优化冻干工艺条件下，甘露醇和蔗糖合用为冻干保护剂，可得到外观良好、易于重建的冻干脂质体，冻干前后的药物包封率分别为97．1％和96．2％，粒径分别为175．1nm和227．9nm。-20℃及4℃贮存3个月，粒径和包封率无显著变化。采用大鼠在体鼻腔循环灌流法，考察了尼莫地平鼻用脂质体及其冻干重建制剂的鼻黏膜吸收规律。结果表明不同药物浓度脂质体及冻干重建脂质体的鼻黏膜吸收速率常数K无显著性差异，药物吸收呈一级动力学特征。     

苦参碱脂质体处方与工艺优化研究

目的 :筛选苦参碱脂质体的最优处方和最佳制备工艺。方法 :采用逆相蒸发法制备苦参碱脂质体 ,以包封率和粒径作为考察指标 ,应用正交试验法优选苦参碱脂质体的处方和制备工艺。结果 :最佳处方为卵磷脂80mg、胆固醇15mg 组成油相 ,pH=7 0磷酸盐缓冲液、苦参碱30mg 组成水相 ;最佳制备工艺为氯仿30ml ,超声时间10min ,旋转蒸发温度48℃。以优化工艺制得的脂质体形态均匀 ,粒径在250nm～750nm之间 ,包封率为47 25 %。结论 :经优选得到的苦参碱脂质体处方合理、工艺可行、包封率较高、稳定性好。     

CA4P脂质体的制备工艺研究

目的 研究CA4P脂质体的处方及制备工艺.方法 以包封率为主要评价指标考察制备方法;用透射电镜和粒径测定仪表征脂质体的形态和粒径;用HPLC法测定脂质体中CA4P的包封率和载药量;以正交设计筛选优化最佳处方工艺.结果 脂质体的平均粒径为167 nm,Zeta电位为-24.3 mV,最佳工艺处方的药-脂比为1:12,磷脂-胆固醇为8:1,有机相-水相体积为4:1,水合介质为0.9%NaCl;制备3批脂质体的平均包封率为58%、载药量为4.8%.结论 逆相蒸发-探头超声法可制备具有较高包封率的CA4P脂质体.     

毛果芸香碱脂质体的制备及其质量评价

目的：研究毛果芸香碱脂质体滴眼剂的处方和制备工艺，并对其质量进行评定。方法：采用逆相蒸发法制备毛果芸香碱脂质体，以包封率为指标通过正交试验法优选处方，用透射电镜和粒径测定仪测定脂质体的形态和粒径分布，用高效液相色谱法测定脂质体中毛果芸香碱的含量和包封率。结果：制备的脂质体形态归整，数均粒径为69．5nm，药物包封率为47．42％，体外药物释放时间明显延长，8h时释放94．12％。结论：本研究所得的处方和工艺可制备性能优良的毛果芸香碱脂质体。     

猪苓多糖长循环脂质体的制备及其质量控制

目的：研究猪苓多糖长循环脂质体的制备方法，并对其质量进行控制。方法：逆相蒸发法制备猪苓多糖长循环脂质体，采用紫外分光光度法测定脂质体中猪苓多糖的包封率和载药量，透射电镜观察形态，激光散射法测定粒径大小，离心加速实验考查稳定性。结果：猪苓多糖长循环脂质体平均粒径为67．8nm，药物平均包封率为93．10％，平均载药量为13．68％。脂质体外观圆整而均匀，渗漏率小，稳定性好。结论：用逆相蒸发法可制备包封率高、稳定性好的猪苓多糖长循环脂质体。质量控制方法简单，快速准确，重复性好。     

Use of liposomes as injectable-drug delivery systems

The formation of liposomes and their application as delivery systems for injectable drugs are described. Liposomes are microscopic vesicles composed of one or more lipid membranes surrounding discrete aqueous compartments. These vesicles can encapsulate water-soluble drugs in their aqueous spaces and lipid-soluble drugs within the membrane itself. Liposomes release their contents by interacting with cells in one of four ways: adsorption, endocytosis, lipid exchange, or fusion. Liposome-entrapped drugs are distributed within the body much differently than free drugs; when administered intravenously to healthy animals and humans, most of the injected vesicles accumulate in the liver, spleen, lungs, bone marrow, and lymph nodes. Liposomes also accumulate preferentially at the sites of inflammation and infection and in some solid tumors; however, the reason for this accumulation is not clear. Four major factors influence liposomes' in vivo behavior and biodistribution: (1) liposomes tend to leak if cholesterol is not included in the vesicle membrane, (2) small liposomes are cleared more slowly than large liposomes, (3) the half-life of a liposome increases as the lipid dose increases, and (4) charged liposomal systems are cleared more rapidly than uncharged systems. The most advanced application of liposome-based therapy is in the treatment of systemic fungal infections, especially with amphotericin B. Liposomes are also under investigation for treatment of neoplastic disorders. Liposomes' uses in cancer therapy include encapsulation of known antineoplastic agents such as doxorubicin and methotrexate, delivery of immune modulators such as N-acetylmuramyl-L-alanine-D-isoglutamine, and encapsulation of new chemical entities that are synthesized with lipophilic segments tailored for insertion into lipid bilayers. Liposomal formulations of injectable antimicrobial agents and antineoplastic agents already are undergoing clinical testing, and most probably will receive approval for marketing in the early 1990s. Liposomal encapsulation of drugs represents a new drug delivery system that appears to offer important therapeutic advantages over existing methods of drug delivery.     

Liposomal delivery system enhances anti-inflammatory properties of curcumin

Curcumin is a well-established natural antioxidant and anti-inflammatory agent. Up till now its potential in treatment of vaginal inflammation has not been evaluated. We are aiming at developing liposomal delivery system for curcumin targeting vaginal administration. Liposomes as nanosized phospholipid-based vesicles are expected to solubilize curcumin and enhance its activity, thus serving as an advanced topical formulation in the treatment of vaginal inflammation. Curcumin and curcuminoids were analyzed by the high-performance liquid chromatography method. Liposomes containing curcumin/curcuminoids of various sizes were prepared and characterized. Antioxidant activities of curcumin and liposomal curcumin were compared based on 1,1-diphenyl-2-picrylhydrazyl radical scavenging and superoxide dismutase activities. The anti-inflammatory activities were determined by measuring the inhibition of lipopolysaccharide -induced nitric oxide, interleukin-1β, and tumor necrosis factor-α production in macrophage RAW 264.7 cells. Curcumin/curcuminoids were encapsulated in phosphatidylcholine vesicles with high yields. Vesicles in the size range around 200 nm were selected for stability and cell experiments. Liposomal curcumin were found to be twofold to sixfold more potent than corresponding curcuminoids. Moreover, the mixture of curcuminoids was found to be more potent than pure curcumin in regard to the antioxidant and anti-inflammatory activities. Liposomal delivery systems for curcumin are promising formulations for the treatment of vaginal inflammation.     

The Use of Liposomes as Snake Venom Vehicles. Application in Protective Immunization

Abstract

Liposomes (phospholipid-based vesicles) have been widely studied as drug delivery systems due to their structural versatility concerning size, composition, bilayer fluidity and their ability to incorporate almost any molecule regardless of its nature. Liposomes are successful for inducing potent immunity in vivo and they are now being employed in numerous irnmunization procedures and as vehicles for vaccines. This is a brief overview of the use of liposomes as carriers of venom antigens and immunomodulators, a safe and potent alternative for the production of antivenom and for the active immunization of dommestic animals in areas of high incidence of envenomation and mortality. Other potential applications of venom-containing liposomes are also presented.     

Impact of membrane properties on uptake and transcytosis of colloidal nanocarriers across an epithelial cell barrier model

The aim of this study was to investigate the effect of liposomal membrane properties on cellular uptake and transcytosis across a tight Madin–Darby canine kidney (MDCK) cell barrier in vitro. More than 25 small vesicles were prepared by lipid film hydration/extrusion to generate small unilamellar vesicles. The fluorescence marker calcein was encapsulated to mimic hydrophilic drug transport. Marker uptake by MDCK cells seems to be mediated by different mechanisms for the liposomes used. It was mainly depending on membrane fluidity and vesicle charge. Liposomes L2 with a positive charge (325 ± 3 pmol/well) and vesicles L3 containing the helper lipid dioleylphosphatidylethanolamine (DOPE) in their membrane (216 ± 42 pmol/well) were taken up to the most. Selected liposomes were tested for their transcytotic transport across a MDCK monolayer. Liposomes L4 containing equimolar DOPE and octadecyl‐1,1‐dimethylpiperidin‐1‐ium‐4‐yl phosphate (OPP) were the most efficient vesicles for transcellular transport resulting in 808 ± 30 pmol calcein/cm² in the basal medium (28.1% of total liposomal marker added). Transcytosis was positively correlated with membrane fluidity in the outer part of the bilayer, as electron paramagnetic resonance measurements revealed. We expect that an increase in membrane fluidity of vesicles should also improve the restricted transport of hydrophilic drugs across the blood–brain barrier. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2423–2433, 2010     

Liposome: composition,characterisation, preparation,and recent innovation in clinical applications

Abstract

In the last decades, pharmaceutical interested researches aimed to develop novel and innovative drug delivery techniques in the medical and pharmaceutical fields. Recently, phospholipid vesicles (Liposomes) are the most known versatile assemblies in the drug delivery systems. The discovery of liposomes arises from self-forming enclosed phospholipid bilayer upon coming in contact with the aqueous solution. Liposomes are uni or multilamellar vesicles consisting of phospholipids produced naturally or synthetically, which are readily non-toxic, biodegradable, and are readily produced on a large scale. Various phospholipids, for instance, soybean, egg yolk, synthetic, and hydrogenated phosphatidylcholine consider the most popular types used in different kinds of formulations. This review summarises liposomes composition, characterisation, methods of preparation, and their applications in different medical fields including cancer therapy, vaccine, ocular delivery, wound healing, and some dermatological applications.     

The effects of amrinone, cyclophosphamide and anti-platelet serum on platelet production in the Gunn rat

The effect of amrinone on platelet production was differentiated from that of a known bone-marrow cytotoxic agent (cyclophosphamide) and anti-platelet serum (APS). The rate of platelet production has been observed over a 4-day period in the Gunn rat using [75Se]selenomethionine cohort labelling of platelets following administration of either amrinone, 160 mg kg-1 day-1, cyclophosphamide, 30 mg kg-1 day-1 or APS, 0.75 ml. Platelet numbers were reduced by amrinone, cyclophosphamide and APS. The rate of platelet production was increased following APS and suppressed by cyclophosphamide, but the rate of platelet production when expressed as the selenomethionine incorporation in counts per minute (cpm) per 10(8) platelets appeared to be increased in amrinone-treated animals. When these values are expressed as radioactivity per unit platelet volume the difference between the control and the amrinone-treated group was reduced but the difference between the control, APS- and cyclophosphamide-treated groups remained unchanged. It is concluded that in the Gunn rat amrinone affects platelet production by producing fewer, larger platelets.     

Liposomes for drug delivery: developments and possibilities

The ability to target a drug specifically to its site of action has long been a goal in therapeuties. Liposomes (phospholipid vesicles) have been investigated as a means of achieving such selectivity and of prolonging the duration of drug activity. With reference to current and future clinical applications, this article outlines why liposomes are appropriate vehicles for drug delivery and describes the possible further development of liposome-based pharmaceutical formulations.     

黄芪多糖对烧伤小鼠细胞免疫功能的作用

应用小鼠烧伤模型，对黄芪多糖（ＡＰＳ）的免疫增强作用进行了体内外研究。结果表明：体内应用ＡＰＳ（２５０ｍｇ·ｋｇ－１，ｑｄ，连续５ｄ），可明显提高烧伤小鼠Ｔ淋巴细胞转化，ＩＬ－２的产生及ＩＬ－２Ｒ的表达；体外分别应用５０、１００、２５０ｍｇ·Ｌ－１的黄芪多糖，发现其可纠正烧伤小鼠Ｔ淋巴细胞转化，ＩＬ－２的产生及ＩＬ－２Ｒ表达的受抑状态，并促进巨噬细胞产生ＩＬ－１，抑制ＰＧＥ２合成，且呈剂量依赖关系；体外去除烧伤小鼠脾细胞中的巨噬细胞后，ＡＰＳ对Ｔ淋巴细胞转化，ＩＬ－２产生及ＩＬ－２Ｒ表达的调节作用消失。提示ＡＰＳ对烧伤小鼠的免疫调节作用依赖于巨噬细胞，通过调节其分泌ＩＬ－１，抑制ＰＧＥ２合成，而促进ＩＬ－２产生及ＩＬ－２Ｒ表达，进而增强Ｔ淋巴细胞增殖。     

In vitro evaluation of enrofloxacin-loaded MLV liposomes

Fluoroquinolones are broad-spectrum antimicrobial agents that seem to reach their intracellular target site (DNA gyrase) in Escherichia coli by means of an uptake process through the outer and inner membranes. Delivery of quinolones with liposomes has many advantages than the free form of the drug. Liposomes may represent an excellent device for improving the selective transport of antibiotics in these respects. In this study, enrofloxacin-loaded multilamellar vesicles (MLVs) were prepared and the effects of formulation variables on the liposome characteristics were investigated. Liposomes were prepared by using the dry lipid film method. A number of variables, such as phospholipid (DL-alpha -phosphatidylcholine dipalmitoyl), cholesterol, enrofloxacin (ENF), stearylamine, and dicetyl phosphate molar ratios and alpha -tocopherol amounts, were studied. The liposome size, encapsulation capacity, drug release, stability, and electrophoretic mobility of ENF-loaded liposomes were determined. Using this method, spherical MLVs with high drug content could be produced. Particle size of liposomes changed between 1.63 and 3.31 micro m and liposome size was affected by all formulation variables (p < 0.05) except molar ratio of ENF. MLVs can be used as a carrier system for the controlled release of ENF. The highest encapsulation of ENF amount can be obtained using positively charged SA in the formulation and changing the formulation parameters can vary drug release patterns.