聚乳酸、聚乳酸乙醇酸共聚物微球的制备及体外释放影响因素研究进展

目的:对近年来以PLA、PLGA为载体的微球剂的研究进展进行综述。方法:查阅近10年来有关PLA、PLGA微球研究的国内外文献,介绍此类微球的制备方法和影响其体外释放等性质的主要因素。结果:PLA、PLGA的性质、药物的性质及微球的制备工艺等对微球的体外释放等性质均有重要的影响。结论:对以PLA、PLGA为载体制备的药物微球,有待于更进一步的研究和开发     

长春西汀聚乳酸-聚乙醇酸缓释微球的研制

目的:制备长春西汀聚乳酸-聚乙醇酸(PLGA)缓释微球,并研究其药剂学性质。方法:采用改良O/W乳化-溶剂挥发法制备微球,以PLGA浓度、理论载药量、有机相与分散介质的比例和分散介质中明胶的浓度为4因素,每个因素选定3个水平,按L9(34)的正交设计方案,以载药量、包封率和粒径分布为指标,优化处方。用扫描电镜观察微球的形态,用光学显微镜观察并计算微球的粒径分布,用差示扫描量热(DSC)法研究药物在载体中的分散状态,用紫外分光光度法检测微球中长春西汀含量并计算载药量和包封率,用动态透析释药法进行微球的体外释放研究。结果:最佳处方为PLGA浓度16%,理论载药量20%,有机相与分散介质的比例1:10,分散介质中明胶的浓度1%;制备的长春西汀PLGA缓释微球的形态圆整、光滑,粒径分布均匀,平均粒径为(10.0±0.18)μm(n=500),DSC法分析药物确已被包裹于微球中,载药量为(18.46±0.26)%,包封率为(91.30±0.98)%(n=3),24h累积释药率约为18%。结论:长春西汀PLGA缓释微球制备工艺稳定,质量符合药剂学要求,缓释性好。     

聚乳酸、聚乳酸乙醇酸共聚物微球的制备及影响其质量因素的研究进展

本文综述了近年来以聚乳酸、聚乳酸乙醇酸共聚物为载体的微示的研究进展,并介绍此类微球的制备方法及影响其质量的主要因素。研究表明,载体和药物的性质及微球的制备工艺等对微球的质量和体外释放等均有重要的影响。     

聚乳酸、聚乳酸乙醇酸共聚物微球的制备及体外释放影响因素研究进展

目的：对近年来以PLA，PLGA为载体的微球剂的研究进展进行综述。方法：查阅近10年来有关PLA，PLGA微球研究的国内外文献，介绍此类微球的制备方法和影响其体外释放等性质的主要因素。结果：PLA，PLGA的性质，药和折性质及微球的制备工艺等对微球的体外释放等性质均有重要的影响。结论：对以PLA，PLGA为载体制备的药物微球，有待于更进一步的研究和开发。     

甲睾酮聚乳酸缓释微球的制备

目的：制备甲睾酮聚乳酸缓释微球。方法：用乳化溶剂挥发法制备甲睾酮聚乳酸缓释微球。先设计单因素试验筛选制备微球的处方中的聚乳酸分子量、聚乳酸浓度、投药比（甲睾酮：聚乳酸）;再采用正交试验优化制备微球的温度、转速、聚乳酸浓度、投药比。考察微球表面形态、粒径、载药量、包封率、168h体外累积释药率,并对微球的体外释药模型进行零级、一级、Higuchi、双相动力学方程拟合。结果：优选结果为聚乳酸分子量11万、温度30℃、转速500r·min-1、聚乳酸浓度0.1g·mL-1、投药比1：5。采用最佳工艺条件制备的微球形态圆整,平均粒径为（2.5±0.2）μm,载药量为6.18%～6.62%,包封率为89.9%～91.3%,168h体外累积释药率为（41.8±0.1）%,微球的体外释药符合双相动力学方程（r=0.9945）。结论：甲睾酮聚乳酸缓释微球制备工艺稳定,具有良好的缓释能力。     

糖皮质激素缓释微球的制备与性质

目的:制备糖皮质激素微球,探讨工艺条件对成球的影响,并测定微球粒径及体外药物溶出度、药物释放时间等性质.方法:以胶原、壳聚糖、明胶等3种天然生物高分子作材料,采用复乳-交联法制备糖皮质激素微球,用显微镜和扫描电镜观察微球形态和粒径分布.模拟探讨糖皮质激素微球的药物释放行为,用反相高效液相色谱法(HPLC)测定微球释放出的药物浓度.结果:按本工艺制作的微球,有90.8%粒径在20～100μm范围内,平均粒径66.6μm,大小适中,体外模拟实验表明,经过7d,药物溶出率约为51.7%～67.8%,与释放介质的pH值相关,具有较好的缓释性能.结论:该缓释体系有望作为新型的糖皮质激素药物新剂型.     

聚乳酸／乳酸／-乙醇酸共聚物微球制剂研究的新进展

简要介绍了PLA／PLGA及其制剂的原理，并叙述近年来国内PLA／PLGA在新型微球基材、蛋白质和多肽类药物微球、疫苗佐剂类微球和化学合成药物微球的进展情况。     

药用缓释材料聚乳酸-乙醇酸共聚物的研制

目的：合成药用聚乳酸-乙醇酸高分子缓释材料，用于某些生物药物缓、控释剂型的制备；同时探讨聚合反应条件的影响因素以及优化工艺。方法：在一定的温度和压力下，采用配位-插入聚合法通过交酯开环合成聚乳酸-乙醇酸共聚物缓释材料。结果：本研制合成的聚乳酸-乙醇酸共聚物（PLGA75／25和PLGA50／50）经采用多种鉴定手段表征化学结构正确，力学性能良好，玻璃转化温度为33．7℃，分子量为27000～70000，分子量分布为1．4～1．6，产品最终产率可达70％以上。结论：通过制备工艺条件的控制和优化，在一定范围内，不仅可以得到分子量大小不等和单体比例不同的聚乳酸-乙醇酸缓释材料，而且每批次之间所得分子量重现性良好，合成工艺稳定、可靠。     

聚乳酸聚乙醇酸微球体外突释的影响因素的研究

目的 考察几种影响干扰素α-2b聚乳酸聚乙醇酸(PLGA)微球体外释放突释的主要因素.方法 在复乳法的基础上结合海藻酸钠与钙离子螯合形成缓释凝胶的原理制备微球,研究海藻酸钠种类和浓度、PLGA黏度和浓度对微球突释的影响.结果 制备的微球形态圆整,结构致密,平均粒径范围为25～55 μm.微球的突释随着PLGA黏度或浓度...     

聚乳酸-乙醇酸微球的生物降解性和生物相容性研究

目的 考察基因重组人干扰素α-聚乳酸乙醇酸微球的生物降解性和生物相容性.方法 以缓冲液为介质,通过光学显微镜观察聚乳酸乙醇酸微球的体外降解;以Wistar大鼠为研究对象,观察给药部位的病理切片,评价微球的体内生物降解和生物相容性.结果 聚乳酸乙醇酸微球在体外,6周降解百分率超过80%,在体内6周可降解完全;给药部位病理切片观察,仅见轻微炎症反应,未见病理变化.结论 聚乳酸乙醇酸微球具有良好的生物降解性和生物相容性.     

河豚毒素缓释微球含量测定方法的建立

目的 建立测定河豚毒素(TTX)缓释微球中的含量检测方法。方法 采用HPLC法,色谱柱为Agilent Zorbax SB C₁₈柱(4.6 mm×150 mm,5μm);流动相为5%乙腈-95%8 mmol/L庚烷磺酸钠溶液(0.005%TFA,pH4.0);流速1.0 ml/min;紫外检测波长200 nm;柱温30℃。结果 该方法专属性好,TTX在1～20μg/ml浓度范围内线性良好,该方法日内精密度、日间精密度、稳定性、重复性均符合要求,加样回收率范围为98.0%～102.0%。结论 本研究建立了适用于缓释微球中河豚毒素含量测定的HPLC方法,该方法准确可靠,专属性强,可以实现定量检测。     

乳酸羟乙醇酸共聚物微球中蛋白包封率的测定

目的:寻求一种合适的方法测定蛋白在乳酸羟乙醇酸共聚物(PLGA)微球中的包封率。方法:采用复乳 溶剂挥发法制备 BSA的PLGA微球,应用考马斯亮蓝法测定总蛋白浓度,根据文献报道的7种不同方法进行包封率测定。结果:不同的测定方法对 PLGA微球中真实的药物包封率的反映程度不同,相互间差异很大。结论:以水解法测定BSA在PLGA微球中包封率的方法提取 最完全。水解法中,又以乙腈作溶剂、再用氢氧化钠水解两步提取法最为简便、快速、准确。     

Alendronate PLGA microspheres with high loading efficiency for dental applications

Purpose: Alendronate sodium, used systemically as a bone protective agent, proved to also be effective locally in various dental bone applications. Development of alendronate-loaded microspheres with high loading efficiency for such applications would be greatly challenged by the hydrophilicity and low MW of the drug. The aim of this study was to incorporate alendronate sodium, into poly (lactide-co-glycolide) (PLGA) microspheres (MS) with high loading efficiency.

Methods: Three multiple emulsion methods: water-in-oil-in-water (W/O/W), water-in-oil-in-oil (W/O₁/O₂) and solid-in-oil-in-oil (S/O₁/O₂) were tested. In addition to entrapment efficiency, MS were characterized for surface morphology, particle size, in vitro drug release and in vitro degradation of the polymer matrix. Alendronate microspheres with maximum drug loading and good overall in vitro performance were obtained using the W/O₁/O₂ emulsion technique.

Results: Drug release from the microspheres exhibited a triphasic release pattern over a period of 13 days, the last fast release phase being associated with more rapid degradation of the PLGA matrix.

Conclusions: Biocompatible, biodegradable PLGA microspheres incorporating alendronate sodium with high loading efficiency obtained in this study may offer promise as a delivery system for bisphosphonates in dental and probably other clinical applications.     

A novel accelerated in vitro release method to evaluate the release of thymopentin from PLGA microspheres

Abstract

A novel accelerated method of good correlations with “real-time” release to evaluate in vitro thymopentin release from poly (d, l-lactide-co-glycolide) (PLGA) microsphere was developed. Thymopentin-loaded microspheres were made from three types of PLGA, and peptide release was studied in various conditions. Incomplete release of peptide (<60%) from microspheres was found in accelerated testing with two typical release media. This problem was circumvented by adding organic solvents to the release media and varying the temperature in the media heating process. Release media containing three kinds of organic solvents at 50?°C were tested, respectively, and hydro-alcoholic solution was selected for further study. After the surfactant concentration (0.06%, W/V) and ethanol concentration (20%, V/V) were fixed, a gradient heating program, consisting of three stages and each stage with a different temperature, was introduced to enhance the correlations between the short- and long-term release. After adjusting the heating time of each stage, a good correlation (R²?=?9896, formulation 8?K; R²?=?0.9898, formulation 13?K; R²?=?0.9886, formulation 28?K) between accelerated and “real-time” release was obtained. By optimizing the conditions as ethanol concentration and temperature gradients, this accelerated method may be appropriate for similar peptide formulations that not well correlate with “real-time” release.     

阿霉素微球的制备工艺的优选

目的:研究阿霉素PLGA(乳酸-羟基醋酸共聚物)微球制备的最佳工艺。方法:采用“复乳-液中干燥”法制备阿霉素PLGA微球。通过正交试验结合多指标综合评价法优选最佳制备工艺。结果:通过对正交实验Z值结果进行分析,最佳制备工艺为:A3B1C1。结论:正交试验结合多指标综合评价法用于载药微球的制备工艺优化实用有效。     

醋酸戈舍瑞林缓释微球的制备及体外释药研究

目的制备醋酸戈舍瑞林缓释微球,考察其一般性质和体外释药特性。方法采用复乳-液中干燥法制备醋酸戈舍瑞林微球,测定微球的外观形态、粒度分布和体外释药曲线。结果微球形态规则,粒径约为85.6μm,微球体外释药规律符合Higuchi方程：Q=16.202t1/2＋1.550 3,r=0.991 0。结论制备的醋酸戈舍瑞林微球具有长时间的缓释作用。     

Encapsulation and release characteristics of DCTN/PLGA microspheres

In the present study, poly (D,L-lactic-co-glycolic)-acid microspheres containing trans-Dehydrocrotonin (DCTN) were prepared by the double emulsion method. The hypoglycemic activity of DCTN-loaded microspheres was monitored in normal glycemic mice after administration of a daily dose of DCTN (50 mg kg^?1 body weight) for 7 days. Spherical microspheres with two populations of particles with 3.20 ± 0.10 and 7.60 ± 0.70 µm mean diameter size µm were observed. The encapsulation efficiency of DCTN was 85.5 ± 3.9%. The in vitro kinetic profile of DCTN from PLGA-microspheres was initially fast (burst effect of 19.4% at 2 h). Such a burst step was maintained until achieving 35.7±2.0% at 7h, followed by a gradual release of DCTN attaining a maximum drug release at 55.7 ± 2.6% within 30 h. DCTN was able to reduce glucose levels (14.3%) of normal glycemic animals and this effect was improved by its encapsulation into microspheres (26.8%). The optimum glucose levels in the blood of animals treated with DCTN suspension and DCTN-loaded microspheres were 119.21 ± 19.75 mg dL^?1 at day 5 and 103.08 ± 18.88 mg dL^?1 at day 7, respectively. DCTN-loaded microspheres are thus offered as a potential delivery system for the treatment of metabolic diseases characterized by hyperglycemia.     

Specific and non-specific phagocytosis of ligand-grafted PLGA microspheres by macrophages

We evaluated the influence of ligand grafting on the rate and intensity of uptake of poly(d,l-lactide-co-glycolide) microparticles by alveolar macrophages. Microspheres with a mean diameter of 2.5 μm were obtained by spray drying. Three ligands (WGA, an RGD containing peptide and mannose-PEG₃-NH₂) and a cationic molecule (PLL) were covalently grafted on the particle surface using the carbodiimide method. Their grafting efficiency was quantified, and WGA grafting was characterized by confocal laser scanning microscopy (CLSM) and by atomic force microscopy (AFM). The uptake by macrophages of surface-modified microspheres was quantified by CLSM. This work showed that the uptake of negatively charged ligand-grafted microspheres (−26 to −51 mV) was increased up to two to four times according to the ligand compared to ungrafted microspheres (−81 mV) and displayed saturation as opposed to the cationic PLL-grafted microspheres. Moreover, a specific receptor-mediated phagocytosis mechanism was suggested based on free ligand, cytochalasin D and +4 °C incubation that decreased the microparticle uptake. Furthermore, this work clearly showed that the relative contribution of specific and non-specific processes to the overall uptake varied greatly according to the ligands, and was dependent on the particle-to-cell ratio. In conclusion, this work showed that ligand grafting can enhance the uptake of microparticles, with a variable relative contribution of specific and non-specific uptake mechanism.     

Effects of alginate coated on PLGA microspheres for delivery tetracycline hydrochloride to periodontal pockets

The effects of alginate coated on tetracycline (Tc) loaded poly (D, L-lactic-co-glycolic acid) (PLGA) microspheres fabricated by double emulsion solvent evaporation technique for local delivery to periodontal pocket were investigated. Alginate coated PLGA microspheres showed smoother surface but enlarged their particle sizes compared with those of uncoated ones. In addition, alginate coated microspheres enhanced Tc encapsulation efficiency (E.E.) from 11.5?±?0.5% of uncoated ones to 17.9?±?0.5%. Moreover, all of the coated PLGA microspheres even fabricated at different conditions could prolong Tc release from 9–12 days with 50% or higher in cumulative release of Tc compared with those of uncoated ones. The swelling ratios of PLGA microspheres for alginate coated or uncoated ones, one of the possible mechanisms for enhancing Tc release for the coated ones, were measured. The results showed that 20% or higher in swelling ratio for the coated microspheres at the earlier stage of hydration (e.g.?≤?24?h) could be an important factor to result in high Tc release compared to the uncoated ones. In conclusion, alginate coated Tc loaded PLGA microspheres could enhance Tc delivery to periodontal pocket by enhancing drug encapsulated efficiency, released quantities and sustained release period compared with uncoated ones.     

An overview of preparation and evaluation sustained-release injectable microspheres

Recently, sustained-release injectable microspheres as a novel parenteral administration system have been interested on for many years, due to the excellent advantages when compared to traditional dosage forms: less administration frequency, lower adverse side effects and no need for a surgical procedure. Therefore, major progresses in the development of another successful marketed sustained-release injectable formation have been made, but most investigations are merely limited in laboratory levels; in addition, few reports focus on giving some positive guidance to launch these novel microspheres into market. This review addressed some commonly used polymers, preparation methods and sterilization processes relating to biodegradable microspheres. Moreover, the processes for measuring the sustained-release behaviour of this novel system are summarized in this report, including the methods to determine the in vitro and in vivo release behaviours and the strategies to analyse the in vitro and in vivo correlations.