Characterization, lung targeting profile and therapeutic efficiency of dipyridamole liposomes

The acute respiratory distress syndrome (ARDS) is a severe form of acute lung injury (ALI). Its pathogenesis is closely linked with reactive oxygen species (ROS). Antioxidation has been considered as an efficient treatment. Besides, liposomes are widely investigated as potential drug carriers due to their ability to protect and carry drug molecules to the target organ such as the lung. The present study was undertaken to investigate whether dipyridamole (DIP), delivered as a liposomal preparation, can ameliorate the lipopolysaccharides (LPS)-induced ALI due to the changes of its biodistribution. First, the liposomes entrapping DIP were prepared by film hydration for treating ARDS. Subsequently, the characterizations including entrapment efficiency, size, span and micrograph of DIP liposomes were measured. The concentration change of DIP in tissues and plasma of mice after intravenous administration of DIP injection and DIP liposomes was determined by RP-HPLC and calculated to lung targeting parameters. To prove the therapeutic efficiency, the effects of DIP liposomes on LPS-induced ALI were studied compared with DIP injection. The results showed DIP liposomes have the relative high entrapment efficiency and satisfying particle size. Compared with DIP injection, the liposomes increased the accumulation of DIP in the lung on a vast scale. Furthermore, DIP liposomes alleviated the ALI induced by LPS significantly. All of the results suggested that DIP liposomes have the potential efficacy in treating ALI/ARDS due to their obvious lung targeting.     

Targeted delivery of levofloxacin-liposomes for the treatment of pulmonary inflammation

The present study systematically studied the intravenous injectable formulation of liposomes loaded with levofloxacin, an amphipathic antibiotic. The aim of the present study was to design passive targeting liposomes, which might improve the antibacterial activity by accumulating in lung and reduce side effects such as neurotoxicity and hematotoxicity associated with direct injection of the drug. Levofloxacin-loaded liposomes were prepared by the ammonium sulfate gradients method. The formulated liposomes were found to be relatively uniform in size (7.424 ± 0.689 μm) with a positive zeta potential (+13.11 ± 1.08 mV). The entrapment efficiency of levofloxacin-loaded liposomes ranged from 82.19% to 86.23%. The administered liposomes were composed of soybean phosphatides, cholesterol, levofloxacin, and sulfate which existed in inner liposomes. In vitro drug release was monitored for up to 3 days, and the release behavior was in accordance with the Weibull equation. The levofloxacin-loaded liposomes exhibited a longer elimination half-life (t_1/2β) in vivo compared with the levofloxacin solution after intravenous injection to New Zealand rabbits. The encapsulation of levofloxacin in liposomes also changed its biodistribution in mice after intravenous injection in caudal vein. Liposomal levofloxacin performed significant lung targeting efficiency with area under the concentration–time curve, targeting efficacy (Te), and The intake rate (Re) of lung, all showing obvious increase. In addition, liposomal formulations presented accumulative activity in spleen and liver. Conversely, the biodistribution of liposomal formulation in non-RES sites, such as kidney, brain, heart, and plasma, decreased with descending peak concentration ration (Ce) compared to levofloxacin injection, which potentially resulted in the reduction of the side effects of free drug. These results indicated that the levofloxacin-loaded liposomes were promising passive targeting to lung for pulmonary infection treatment.     

支链淀粉修饰双嘧达莫脂质体的制备及其在小鼠体内的组织分布

目的研究支链淀粉修饰双嘧达莫(DIP)脂质体的制备方法并考察其在小鼠体内的组织分布。方法 采用薄膜-分散法制备普通DIP脂质体；合成两亲性的棕榈酰化支链淀粉并用其修饰DIP脂质体；比较修饰前后包封率、zeta电位、平均粒径和径距的变化；采用反相高效液相法测定小鼠组织中的DIP浓度。结果修饰后DIP脂质体的包封率降低，zeta电位增加，平均粒径和径距无明显变化；普通脂质体可以增强DIP在肺部、肝脏和脾脏的分布，而较之普通脂质体，支链淀粉修饰的脂质体可以进一步增加肺部DIP水平，同时减少DIP在肝脏和脾脏的分布，并延长在肺部的滞留时间。结论与普通脂质体和注射液比较，支链淀粉修饰的脂质体可以改变DIP在小鼠体内的组织分布，具有显著的肺靶向性。     

肺靶向吡非尼酮脂质体的制备及体外释药性质研究

目的：研究肺靶向吡非尼酮脂质体的制备方法并考察其体外释药性质。方法：采用薄膜分散法制备吡非尼酮脂质体;用D-甘露糖修饰脂质体并添加适量十八胺调节脂质体表面电荷;用紫外分光光度法测定包封率;用正交实验优化处方,用透析法考察药物体外释放性质。结果：制得的脂质体平均粒径为581.1nm,表面电荷为-20.61mV,包封率为81.1%,稳定性好。药物体外释药符合Weibull方程。结论：采用薄膜分散法,用D-甘露糖修饰并添加十八胺可制得具有较高包封率及稳定性的吡非尼酮脂质体,有助于提高吡非尼酮的肺靶向性。     

肺靶向羟基喜树碱脂质体的制备及其在小鼠体内的组织分布研究

目的： 研究羟基喜树碱脂质体的制备方法并考察其肺靶向及在小鼠体内的分布。方法： 采用薄膜分散－冻融法制备,添加D-甘露糖和十八胺修饰可得到肺靶向羟基喜树碱脂质体;用HPLC法测定给药后小鼠体内不同组织中的药物浓度。结果： 制得的脂质体平均粒径大于2 μm,表面电荷为+21.5 mV,包封率大于65%,稳定性好,符合要求。羟基喜树碱脂质体和注射液经小鼠尾静脉给药后,脂质体主要被肺摄取,在肺部停留的时间较普通注射剂显著延长,其相对摄取率r_e为60.72,脂质体组的肺靶向效率t_e为17.57。结论： 本实验制得羟基喜树碱脂质体具有较高包封率及稳定性,在小鼠肺部浓度高、滞留时间长,能达到肺靶向目的。     

抗氧化剂硫辛酸对实验性ALI/ARDS大鼠的保护作用研究

目的研究代谢性抗氧化剂硫辛酸(LA)对急性肺损伤/急性呼吸窘迫综合征(ALI/ARDS)模型大鼠的保护作用,为ALI/ARDS药物治疗提供新的途径。方法将ALI/ARDS大鼠分为正常对照组(生理盐水(NS)组)、ALI/ARDS模型组(脂多糖(LPS)组)、LA干预组(LA组)和谷胱甘肽干预组(GSH组),LPS注射30min后分别尾静脉注射LA和GSH。并于注射LPS和NS1、2、4、6h后动态观察血清α-干扰素(TNF-α)水平,6h处死大鼠,观察光镜和电镜下肺组织的病理改变,测定动脉血氧分压(PaO2)、血清脂过氧化物(LPO)水平、肺湿干比(W/D)、肺泡灌洗液(BALF)中蛋白浓度和TNF-α水平。结果LA组光镜和电镜下病理表现较LPS组均有好转;与LPS组比较,LA组和GSH组PaO2水平明显升高(P<0·01),LPO、W/D、BALF中蛋白浓度明显下降(P<0·01);LA和GSH能明显抑制BALF中TNF-α水平;血清中TNF-α水平进行性下降,第1、4、6h时有统计学意义(P<0·01)。结论LA对LPS诱发大鼠ALI/ARDS有保护作用。     

肺靶向阿奇霉素脂质体的制备及其在小鼠体内的分布

目的研究肺靶向阿奇霉素阳离子脂质体的制备方法并考察其在小鼠体内的分布。方法利用旋转薄膜-冻融法制备肺靶向阿奇霉素脂质体。用高效液相色谱法测定给药后小鼠体内各组织中的药物浓度。结果制得的脂质体平均粒径为6.582 μm，表面电荷为+19.5 mV，包封率大于75%，稳定性好。药物体外释药符合Higuchi方程。小鼠尾静脉给药后，阳离子脂质体主要被肺摄取，在肺部的滞留时间明显延长，AUC值约为阿奇霉素溶液的8.4倍。结论采用薄膜-冻融法，添加十八胺可制得具有较高包封率及稳定性的阿奇霉素阳离子脂质体，在小鼠肺部的分布优于注射液，能达到肺靶向目的。     

Preventive effect of tranilast on oleic acid-induced lung injury in guinea pigs

Acute respiratory distress syndrome or acute lung injury (ARDS)/(ALI) involve the severe lung injury with pulmonary vascular hyper-permeability and hypoxemia induced by inflammatory reactions. Since ARDS/ALI carries high mortality, the development of new drugs against ARDS/ALI is required. We examined the effect of tranilast, an anti-allergic drug, on vascular hyper-permeability in the lungs and airways, and on hypoxemia, in oleic acid (OA)-induced acute lung injury, an animal model of ARDS/ALI. The increase in pulmonary and airway vascular permeability and the decrease in partial oxygen pressure of arterial blood induced by an intravenous injection of OA were drastically ameliorated by the oral administration of tranilast in a dose-dependent manner. This is the first report to prove that tranilast prevents pulmonary and airway vascular permeability and hypoxemia induced by OA. These results suggest that tranilast may be a candidate drug for the treatment of ARDS/ALI.     

Protection afforded by a herbal medicine,Sho‐seiryu‐to (TJ‐19), against oleic acid‐induced acute lung injury in guinea‐pigs

Objectives The effect of a herbal medicine, Sho‐seiryu‐to (TJ‐19), on oleic acid‐induced lung injury, an animal model of acute respiratory distress syndrome or acute lung injury (ARDS/ALI), was examined. Methods Acute lung injury was induced by an intravenous injection of 15 μl/kg oleic acid to guinea‐pigs. TJ‐19 was administered by a single oral dose (3 g/kg) or by multiple oral doses (0.75 g/kg). Key findings The decrease in partial oxygen pressure of arterial blood (Pao₂) and the increase in airway vascular permeability induced by the oleic acid injection were attenuated by a single dose of TJ‐19. When TJ‐19 was administered orally twice a day for two weeks and then oleic acid was injected, a potent prophylactic effect of the drug was observed. TJ‐19 also prevented airway vascular hyperpermeability, lung cell injury, oxidative stress and thromboxane A₂ generation, associated with the oleic acid injection. Conclusions TJ‐19 significantly attenuated the oleic acid‐induced lung injury probably through the antioxidative effect and inhibitory effect of thromboxane A₂ generation, although the precise inhibitory mechanisms were not fully elucidated due to the diversity in constituents of the herbal medicine. We suggest that TJ‐19 is a promising drug candidate and a medicinal resource for preventing ARDS/ALI.     

Effectiveness of liposomal-N-acetylcysteine against LPS-induced lung injuries in rodents

Acute lung injury (ALI) and its most severe form, the acute respiratory distress syndrome (ARDS) are frequent complications in critically ill patients and are responsible for significant morbidity and mortality. So far, experimental evidence supports the role of oxidants and oxidative injury in the pathogenesis of ALI/ARDS. In this study, the antioxidant effects of conventional N-acetylcysteine (NAC) and liposomally entrapped N-acetylcysteine (L-NAC) were evaluated in experimental animals challenged with lipopolysaccharide (LPS). Rats were pretreated with empty liposomes, NAC, or L-NAC (25mg/kg body weight, iv); 4h later were challenged with LPS (E. coli, LPS 0111:B4) and sacrificed 20h later. Challenge of saline (SAL)-pretreated animals with LPS resulted in lung injury as evidenced by increases in wet lung weight (edema), increases in lipid peroxidation (marker of oxidative stress), decreases of lung angiotensin-converting enzyme (ACE) (injury marker for pulmonary endothelial cells) and increases in the pro-inflammatory eicosanoids, thromboxane B(2) and leukotriene B(4). The LPS challenge also increased pulmonary myeloperoxidase activity and chloramine concentrations indicative of neutrophil infiltration and activation of the inflammatory response. Pretreatment of animals with L-NAC resulted in significant increases in the levels of non-protein thiols and NAC levels in lung homogenates (p<0.05) and bronchoalveolar lavage fluids (p<0.001), respectively. L-NAC was significantly (p<0.05) more effective than NAC or empty liposomes in attenuating the LPS-induced lung injuries as indicated by the aforementioned injury markers. Our results suggested that the delivery of NAC as a liposomal formulation improved its prophylactic effectiveness against LPS-induced lung injuries.     

血管紧张素转换酶2在SARS病理途径中的作用

人类严重急性呼吸综合征(SARS)相关冠状病毒(SARS-CoV)感染导致的严重急性呼吸系统病变,其临床肺部病理损害特征与急性肺损伤和急性呼吸窘迫病变相似。SARS-CoV可以结合人血管紧张素转换酶(ACE)2,二者结合效率与病毒感染复制能力相关。ACE2与ACE1共同调控肾素-血管紧张素系统,二者的功能平衡维持肺的正常功能。SARS-CoV感染时,其棘突蛋白与ACE2结合,下调人体ACE2水平,肺内ACE2和ACE1功能失衡,血管紧张素Ⅱ过度激活AT1受体,导致肺部毛细血管通透性增加,随之出现肺水肿和急性肺损伤。ACE2是SARS病理途径中的关键因子,在SARS临床治疗和SARS药物研制中有重要意义。     

Preparation and the in-vivo evaluation of paclitaxel liposomes for lung targeting delivery in dogs

Objectives The aim of this study was to develop paclitaxel liposomes for a lung targeting delivery system. Methods The liposomes composed of Tween‐80/HSPC/cholesterol (0.03 : 3.84 : 3.84, mol/mol), containing paclitaxel and lipids (1 : 40, mol/mol), were prepared by a combination of solid dispersion and effervescent techniques, and then subjected to ultrasonication. The pharmacokinetics and biodistribution of liposomal and injectable formulation of paclitaxel in dogs were studied after intravenous administration. Key findings The mean diameter, polydispersity index, zeta‐potential and entrapment efficiency of the liposomes were 501.60 ± 15.43 nm, 0.28 ± 0.02, ?20.93 ± 0.06 mV and 95.17 ± 0.32%, respectively. The liposomal formulation kept stable for at least 3 months at 6 ± 2°C and didn't cause haemolysis. The liposome carrier decreased the area under the curve and terminal half‐life of paclitaxel compared with paclitaxel injection ranging from 0.352 ± 0.031 mg/l*h and 0.0671 ± 0.144 h to 0.748 ± 0.062 mg/l*h and 1.978 ± 0.518 h, respectively. The paclitaxel liposomes produced a drug concentration in the lung that was markedly higher than that in other organs or tissues and was about 15‐fold of that of paclitaxel injection at 2 h. Conclusions To sum up, these results demonstrated that the paclitaxel liposomes are an effective lung targeted carrier in the treatment of lung cancer.     

Pharmacotherapy of acute lung injury and acute respiratory distress syndrome

Acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) are characterized by rapid-onset respiratory failure following a variety of direct and indirect insults to the parenchyma or vasculature of the lungs. Mortality from ALI/ARDS is substantial, and current therapy primarily emphasizes mechanical ventilation and judicial fluid management plus standard treatment of the initiating insult and any known underlying disease. Current pharmacotherapy for ALI/ARDS is not optimal, and there is a significant need for more effective medicinal chemical agents for use in these severe and lethal lung injury syndromes. To facilitate future chemical-based drug discovery research on new agent development, this paper reviews present pharmacotherapy for ALI/ARDS in the context of biological and biochemical drug activities. The complex lung injury pathophysiology of ALI/ARDS offers an array of possible targets for drug therapy, including inflammation, cell and tissue injury, vascular dysfunction, surfactant dysfunction, and oxidant injury. Added targets for pharmacotherapy outside the lungs may also be present, since multiorgan or systemic pathology is common in ALI/ARDS. The biological and physiological complexity of ALI/ARDS requires the consideration of combined-agent treatments in addition to single-agent therapies. A number of pharmacologic agents have been studied individually in ALI/ARDS, with limited or minimal success in improving survival. However, many of these agents have complementary biological/biochemical activities with the potential for synergy or additivity in combination therapy as discussed in this article.     

Paclitaxel targeting to lungs by way of liposomes prepared by the effervescent dispersion technique

In order to develop a novel lung targeting drug delivery system (LTDDS) with large-sized liposomes containing paclitaxel (PTX), the liposomes composed of PTX, phosopholipon 90H and tween-80 were prepared by the effervescent dispersion technique with optimal formulation composition. The liposomes were found to be relatively uniform in particle size (8.166 ± 0.459 μm) with a negative zeta-potential (?12.45 ± 1.34 mv), and high entrapment efficiency (92.20 ± 2.56 %). They kept stable for at least 3 months and exhibited a slow release behavior without any hemolysis reaction. Via intravenous administration in rabbits, the PTX liposomes presented a longer mean residence time and elimination half-life, and a much larger area under the plasma drug concentration–time curve compared with its injection; meanwhile, the liposomes altered its biodistribution and exhibited a significant lung targeting characteristic. For example, the relative intake rate (Re) and the ratio of peak concentration (Ce) of lung were 14.87 and 26.44, respectively. Compared with heart, liver, spleen and kidney, the ratios of targeting efficacy (Te)_liposomes to (Te)_injection of lung were increased by a factor of 20.08, 11.10, 6.97 and 14.41, respectively. To sum up, the liposome could be a promising drug carrier for PTX as LTDDS for lung cancer treatment.     

米诺地尔醇脂质体的制备

目的制备米诺地尔醇脂质体并评价其质量。方法采用乙醇注入法制备米诺地尔醇脂质体,以包封率为评价指标进行正交试验筛选出最佳的处方和工艺。采用HPLC测定主药含量、透析袋法测定醇脂质体的包封率。并对其粒径、电位、包封率等理化性质进行研究。结果各因素最佳的水平组合：药脂重量比为1∶10、胆固醇与大豆磷脂的重量比为1∶2、无水乙醇为处方量的30%。所制醇脂质体为乳黄色,平均粒径为1.103μm,Zeta电位为-3.69 mV,平均包封率为66.7%。结论米诺地尔醇脂质体的制备工艺简便可行,质量稳定可控,为开发新剂型奠定了实验基础。     

Preparation of itraconazole-loaded liposomes coated by carboxymethyl chitosan and its pharmacokinetics and tissue distribution

Liposomes are potential carriers for targeting and controlled drug delivery by the intravenous route. Carboxymethyl chitosan (CMC) is a ramification of chitosan with intrinsic water-solubility. The aim of this study is to prepare itraconazole-loaded liposomes coated by carboxymethyl chitosan (CMC-ITZ-Lips), to evaluate its physico-chemical characteristics and the tissue targeting after being injected intravenously (i.v.). This study uses a film dispersion method to prepare itraconazole-loaded liposomes (ITZ-Lips) prior to coating them with CMC. The concentrations of ITZ in selected organs were determined using reversed-phase high-performance liquid chromatography (HPLC) following i.v. administration of ITZ-Sol, ITZ-Lips, and CMC-ITZ-Lips. CMC-ITZ-Lips had an average diameter of 349.3?±?18?nm with a zeta potential of -35.71?±?0.62 mV and the in vitro antifungal activity was not inhibited by the entrapment. The CMC-ITZ-Lips exhibited a longer elimination half life (t(1/2β)) in vivo compared with ITZ-Sol and ITZ-Lips after i.v. injection to mice. The biodistribution in mice was also changed after ITZ was encapsulated in CMC coated liposomes. CMC-ITZ-Lips performed significant lung targeting efficiency with AUC, Te and Re of lung all showed obvious elevation. In this study itraconazole was successfully encapsulated into carboxymethyl chitosan-modified liposomes for application of injection.     

Evolution of treatments for patients with acute lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are acute life-threatening forms of hypoxemic respiratory failure. ALI/ARDS patients require intensive care with prolonged mechanical ventilation. Despite advances in our understanding of the pathophysiology of ALI/ARDS, mortality rates remain > 30% and survivors suffer significant decrements in their quality of life. The evolving understanding of ALI/ARDS and the complex interactions involved in ALI/ARDS open the door for many potential targets for treatment. The condition is characterised by an acute inflammatory state that leads to increased capillary permeability and accumulation of proteinaceous pulmonary oedema. The changes that occur as a result of this inflammation clinically manifest themselves as hypoxemia, infiltrates on chest radiograph and reduced lung compliance. Many years have been dedicated to analysing the complexities involved in ALI/ARDS in order to improve current and future possibilities for treatment, with the aim of improving patient outcomes. Although some therapies have demonstrated benefits of improved oxygenation, such as surfactant and nitric oxide, these benefits have not translated into reductions in the duration of mechanical ventilation or mortality. Inflammatory mediator-targeted therapies were promising early on; however, larger trials have found therapies such as cytokine modulation, platelet-activating factor inhibition and neutrophil elastase inhibitors to be ineffective in the treatment of ALI/ARDS. Preclinical studies with β2-agonists and granulocyte macrophage colony-stimulating factor have shown promise for restoring alveolar capillary barrier integrity or reducing pulmonary oedema, and further studies are being conducted to test for true clinical benefit. Despite previous therapeutic failures, newer surfactant formulations have shown promise, particularly in patients with direct forms of lung injury, and are currently in Phase III trials. Anticoagulant therapy with activated protein C has been shown to improve survival in sepsis, the most common risk factor for the development of ALI/ARDS, and is now being studied in ALI/ARDS. Until new data emerge, the focus must remain on supportive care, including optimised mechanical ventilation, nutritional support, manipulation of fluid balance and prevention of intervening medical complications.     

重组人生长激素脂质体的制备及载药研究

目的采用乙醇注入法结合反复冻融技术制备重组人生长激素脂质体,并考察影响包封率的主要因素。方法采用乙醇注入法制备空白脂质体,并通过反复冻融载药,采用葡聚糖凝胶柱分离结合CBB G-250染色法测定游离药物含量,计算包封率;考察孵化时间、孵化温度、冻融次数对包封率的影响;对冻干制品的外观、复溶速度、粒径及分布进行综合评分,优选冻干支持剂。结果孵化时间为40 min、孵化温度为10℃、冻融次数为3次时,能够获得较高包封率的脂质体,包封率为63.59%。海藻糖在脂质体冷冻干燥过程中具有最好的保护作用。结论乙醇注入法结合反复冻融可用于大分子蛋白质类脂质体的制备。     

参麦对内毒素型急性肺损伤家兔血清TNF-α、IL-6变化的研究

目的探讨参麦注射液对内毒素型急性肺损伤（ALI）家兔血清TNF-α、IL-6的变化,评价参麦对ALI的保护作用。方法24只家兔随机分为3组：正常对照组、单纯急性肺损伤（ALI）组和参麦治疗组（内毒素型ALI＋参麦治疗）,采用内毒素（LPS）制备成急性肺损伤（ALI）家兔模型后即进行参麦治疗,观察不同时段的血清TNF-α、IL-6的变化及左肺叶组织湿质量/干质量（W/D）值。结果参麦注射液可明显缓解内毒素所致肺损伤,与对照组比较血清TNF-α、IL-6活性、血氧分压有明显改善,经参麦治疗后,W/D值明显下降,渗出减轻。结论TNF-α、IL-6在家兔内毒素型急性肺损伤（ALI）炎症过程中可能起重要作用,参麦注射液可能通过抑制TNF-α、IL-6过量分泌,减轻肺损伤,具有防治ALI作用。