丙交酯-乙交酯共聚物中残留单体的去除

将丙交酯-乙交酯共聚物(PLGA)溶于二氯甲烷中,用稀盐酸为萃取剂(即稀酸萃取法)或乙醇为沉淀剂(乙醇沉淀法)去除PLGA中残留的乙交酯和丙交酯单体.考察了两种方法的工艺参数对单体残留量的影响.结果表明,稀酸萃取法比乙醇沉淀法的去除效果好,但所用盐酸会破坏PLGA;沉淀法能有效避免PLGA的降解,且工艺简单.上述两法的去除效果均优于真空加热法.     

A Heterogeneously Structured Composite Based on Poly(lactic-co-glycolic acid) Microspheres and Poly(vinyl alcohol) Hydrogel Nanoparticles for Long-Term Protein Drug Delivery

Purpose. To prepare a heterogeneously structured composite based on poly (lactic-co-glycolic acid) (PLGA) microspheres and poly(vinyl alcohol) (PVA) hydrogel nanoparticles for long-term protein drug delivery. Methods. A heterogeneously structured composite in the form of PLGA microspheres containing PVA nanoparticles was prepared and named as PLGA-PVA composite microspheres. A model protein drug, bovine serum albumin (BSA), was encapsulated in the PVA nanoparticles first. The BSA-containing PVA nanoparticles was then loaded in the PLGA microspheres by using a phase separation method. The protein-containing PLGA-PVA composite microspheres were characterized with regard to morphology, size and size distribution, BSA loading efficiency, in vitroBSA release, and BSA stability. Results. The protein-containing PLGA-PVA composite microspheres possessed spherical shape and nonporous surface. The PLGA-PVA composite microspheres had normal or Gaussian size distribution. The particle size ranged from 71.5 m to 282.7 m. The average diameter of the composite microspheres was 180 m. The PLGA-PVA composite microspheres could release the protein (BSA) for two months. The protein stability study showed that BSA was protected during the composite microsphere preparation and stabilized inside the PLGA-PVA composite microspheres. Conclusions. The protein-containing PLGA-PVA composite may be suitable for long-term protein drug delivery.     

GM-1PLGA肌注微球的制备及其体外释药评价

目的 研究以聚乳酸羟基乙酸共聚物为囊材,制备长效缓释的单唾液酸四己糖神经节苷脂微球制剂.方法运用复乳溶剂挥发法,考虑多个条件对制备工艺的影响,并采用正交设计对处方进行优化.测定微球的载药量、包封率和释放曲线.结果制备得到的GM-1微球粒径大小均匀,球形致密圆整,微球粒径为(8.2±6.0)μm,载药量和包封率分别为18...     

The Stabilization and Encapsulation of Human Growth Hormone into Biodegradable Microspheres

Purpose. To produce and evaluate sustained-acting formulations of recombinant human growth hormone (rhGH) made by a novel microencapsulation process. Methods. The protein was stabilized by forming an insoluble complex with zinc and encapsulated into microspheres of poly (D,L-lactide co-glycolide) (PLGA) which differed in polymer molecular weight (8–3 1kD), polymer end group, and zinc content. The encapsulation procedure was cryogenic, non-aqueous, and did not utilize surfactants or emulsification. The rhGH extracted from each of these microsphere formulations was analyzed by size-exclusion, ion-exchange and reversed-phase chromatography, SDS-polyacrylamide gel electrophoresis, peptide mapping, and cell proliferation of a cell line expressing the hGH receptor. In addition, the in vivorelease profile was determined after subcutaneous administration of the microspheres to rats and juvenile rhesus monkeys. Results. Protein and bioactivity analyses of the rhGH extracted from three different microsphere formulations showed that the encapsulated protein was unaltered relative to the protein before encapsulation. In vivo, microsphere administration to rats or monkeys induced elevated levels of serum rhGH for up to one month, more than 20-fold longer than was induced by the same amount of protein injected subcutaneously as a solution. The rate of protein release differed between the three microsphere formulations and was determined by the molecular weight and hydrophobicity of the PLGA. The serum rhGH profile, after three sequential monthly doses of the one formulation examined, was reproducible and showed no dose accumulation. Conclusions. Using a novel process, rhGH can be stabilized and encapsulated in a solid state into PLGA microspheres and released with unaltered properties at different rates.     

紫杉醇PLGA微球制备及体外性质评估

目的：以乳酸-羟基乙酸共聚物（PLGA）为材料,制备用于肿瘤内注射的紫杉醇PLGA长效缓释微球.方法：采用改良溶剂蒸发法制备,对微球的体外性质以及不同剂量（10,15,25 kGy）60Coγ射线对微球性质的影响进行考察.结果：制得的微球形态圆整,载药量、包封率、平均粒径和跨距分别为1.53%,97.29%,42.72μm和0.95.药物体外释放30 d累计释放达到56.19%,体外降解30 d后微球失去完整结构,表面粗糙.3个剂量60Coγ射线的灭菌效果均良好,且对微球的体外性质均无明显影响.微球中二氯甲烷的残留量低于药典规定的限度.结论：紫舷杉醇PLGA微球满足缓释长效的要求,对恶性肿瘤的间质化疗具有一定前景.     

水溶性添加剂对聚乳酸-聚乙烯醇酸共聚物基质释药动力学的影响

目的选择不同亲水性及空间构型的添加剂，研究其对聚乳酸-聚乙烯醇酸共聚物(poly lactic-co-glycolic acid, PLGA)药物释放动力学的影响，为心血管药物局部用药控释制剂的研究提供理论依据。方法用抗细胞增生药物2-氨基色酮(U-86)作为代表性药物，用溶剂浇铸和压膜结合的方法制备药物/PLGA/添加剂双层膜，在37 ℃磷酸缓冲液中测定体外药物释放并用扫描电镜观察表面形态。结果水溶性添加剂明显地提高了U-86的释放率，并转变为近似的单阶段模式。药物释放速率与基质的失重速率非常吻合。水溶性添加剂的基质在水中形成高度多孔的结构。结论添加剂的水溶性、分子量大小及空间构型等对于聚合物基质的孔隙结构具有决定性作用，而这些孔隙结构的特征又影响着药物释放机制以及释放动力学模式。     

The pharmacokinetics of recombinant human interferon-alpha-2b poly(lactic-co-glycolic acid) microspheres in rats

Interferon-alpha2b (IFN α-2b) microspheres were prepared at various concentrations (5%, 10%, 15%, 20% and 25%) and viscosities (0.39, 0.6, 0.89 and 1.13?dL/g) of poly(lactic-co-glycolic acid) (PLGA) using double emulsion solvent evaporation. The optimal formulation of IFN α-2b microspheres was determined to be 0.89?dL/g PLGA, as assessed by the in vitro release test. The pharmacokinetics of IFN α-2b microspheres was investigated. Nine groups of rats were injected intramuscularly with three doses (0.5, 1 and 2?MIU) of commercial lyophilized IFNα-2b injection or IFN α-2b microspheres. At a dose of 0.5?MIU, the IFN α-2b microsphere released significantly longer than that of the IFN α-2b injection. At a dose of 2?MIU, each pharmacokinetics parameter of microspheres prepared with the IFNa-2b stock solution was manifestly greater than those of the injection. Our study indicated that the IFN α-2b microspheres prepared in 15% of 0.89?dL/g PLGA provided a sustained drug effect for up to 21 days in rats.     

Preparation and testing of cefquinome-loaded poly lactic-co-glycolic acid microspheres for lung targeting

The aim of this study was to prepare cefquinome-loaded poly lactic-co-glycolic acid (PLGA) microspheres and to evaluate their in vitro and in vivo characteristics. Microspheres were prepared using a spry drier and were characterized in terms of morphology, size, drug-loading coefficient, encapsulation ratio and in vitro release. The prepared microspheres were spherical with smooth surfaces and uniform size (12.4?±?1.2?μm). The encapsulation efficiency and drug loading of cefquinome was 91.6?±?2.6 and 18.3?±?1.3%, respectively. In vitro release of cefquinome from the microspheres was sustained for 36?h. In vivo studies identified the lung as the target tissue and the region of maximum cefquinome release. A partial lung inflammation was observed but disappeared spontaneously as the microspheres were removed through in vivo decay. The sustained cefquinome release from the microspheres revealed its applicability as a drug delivery system that minimized exposure to healthy tissues while increasing the accumulation of therapeutic drug at the target site. These results indicated that the spray-drying method of loading cefquinome into PLGA microspheres is a straightforward method for lung targeting in animals.     

A Novel in Vitro Delivery System for Assessing the Biological Integrity of Protein upon Release from PLGA Microspheres

Purpose. The development of a novel in vitro system is required to assess the stability and release kinetics of a protein microsphere formulation used for drug delivery to the brain. Methods. Microspheres containing lysozyme as model protein were prepared using a (w/o/w) emulsion-solvent evaporation process. Both the active and total (active + inactive) encapsulation efficiencies and release profiles were determined. The biologic activity of lysozyme was measured using bacterial cell lysis; total protein content was measured using a ¹²⁵I-radiolabel. A novel in vitro apparatus was developed to determine kinetics over a sustained time period (>30 days). Results. The microencapsulation technique allowed an entrapment of active lysozyme at 80 ± 4% and a sustained (>42 days) in vitro release. The kinetics study showed that the novel in vitro system was able to detect the release of low amounts (ng) of protein. To improve the stability of the protein within microspheres and allow the release of biologically active lysozyme, a basic additive ( Mg(OH)₂ ) was successfully encapsulated. Conclusions. This novel in vitro system was appropriate to study protein microsphere release kinetics. In addition, the model is cost-effective and mimes brain physiological conditions more closely than previous models.     

Novel Long-Acting Crystal Formulation of Human Growth Hormone

PURPOSE: The aim of the study is to solve a significant challenge of extending the half-life of therapeutic proteins using crystalline biopharmaceuticals and without redesigning the molecules. METHODS: Crystals of recombinant human growth hormone were coated with a monomolecular layer of positively charged poly(arginine). The pharmacokinetics and pharmacodynamics of this poly(arginine)-coated human growth hormone crystalline formulation were determined in hypophysectomized rats and monkeys. RESULTS: Here we have demonstrated for the first time that crystals of human growth hormone coated with positively charged poly(arginine) allowed for in vivo pharmacokinetic release profiles of over several days in animal models. The efficacy of this crystalline formulation injected subcutaneously once a week was found to be equivalent to seven daily soluble injections in the standard weight gain assay using the hypophysectomized rat model and in measurement of serum insulin-like growth factor in monkeys. The nonviscous nature of the suspension facilitated easy administration through a fine, 30-gauge needle and should provide for improved patient convenience and compliance. CONCLUSIONS: The approach described here offers an exciting possibility of being broadly applicable to other therapeutic proteins.     

聚乳酸乙醇酸在微球控释制剂中的研究进展

聚乳酸乙醇酸(PLGA)是生物可降解的聚合物,已取得了美国FDA的批准,用于组织工程支架和药物载体。由于其具有良好的生物相容性和生物可降解性,近20年来成为小分子药物、蛋白质和其他大分子(DNA、RNA或多肽类)化合物的缓释控释制剂研究的热点。对于PLGA微球制剂的研究主要集中在疫苗类、激素类、抗生素类、抗肿瘤类、神经营养物质类等药物控释制剂。主要介绍近5年来这些药物微球的研究情况,为进一步开发利用PLGA作为药物载体提供参考。     

高分子材料对卡铂-乳酸/羟基乙酸共聚物微球体外性质的影响

目的:制备卡铂-乳酸／羟基乙酸共聚物(poly(lactic-co-glycolic acid),PLGA)微球,比较不同PLGA所得微球的体外释药特点。方法:采用乳化-溶剂挥发法制备卡铂-PLGA微球,显微镜下测定微球的粒径和粒径分布。采用电感耦合等离子体质谱(ICP-MS)测定微球含药量,计算包封率,考察微球体外释药行为。结果:PLGA来源和规格不同,对微球的形态、粒径、载药量和包封率没有明显影响,所得微球球形较好,平均粒径为38-54μm,含药量为6．4-7．2μg·mg-1,包封率16．3％-22．7％。药物体外释放行为随PLGA不同而有很大差异,PLGA 50／50微球突释快,突释率高。PLGA(50／50,η=0．18)和PLGA(50／50,η=0．53)的微球2 h药物突释率分别为55．06％和83．10％;PLGA(75／25,η=0．19)和PLGA(75／25,η=0.30)的微球12 h药物突释率分别为38．43％和44．04％。缓慢释放期PLGA(50／50,η=0．53)微球释药符合零级释放模型,其他3种材料的微球符合Higuchi释放方程,PLGA (50／50,η=0．18)和PLGA(75／25,η=0．19)微球体外较好地控制药物释放,缓释期药物释放速度常数分别为1．18和2.40 h-1/2。结论:PLGA来源和组成不同,制备的微球体外释药行为差异较大。PLGA(75／25,η=0．19)微球体外较好地控制卡铂的释放。     

Immunotoxicity of poly (lactic-co-glycolic acid) nanoparticles: influence of surface properties on dendritic cell activation

Abstract

Modified nanoparticles (NPs) can interact with the immune system by causing its activation to fight tumors or for vaccination. During this activation, dendritic cells (DCs) are effective in generating robust immune response. However, the effect of nanomaterials on dendritic cell (DC) maturation, and the associated adjuvant effect, should be assessed as a novel biocompatibility criteria for biomaterials since immune consequences may constitute potential complications in nanomedicine. Among emerging biomaterials, poly(lactic-co-glycolic acid) NPs (PLGA NPs) are widely explored for various applications in which the degree of desired adjuvant effect may vary. As contradictory results are reported regarding their effects on DCs, we aimed at clarifying this point with particular emphasis on the relative impact of particle surface properties. To that end, NP uptake and effects on the viability, phenotype, and secretory activity of DC primary cultures. Intracellular signaling pathways were explored and evaluated. Immature human and murine DCs were exposed to cationic, neutral, or anionic PLGA NPs. Particle uptake was assessed by both confocal microscopy and flow cytometry. Cell viability was then evaluated prior to the study of maturation by examination of both surface marker expression and cytokine release. Our results demonstrate that PLGA NPs are rapidly engulfed by DCs and do not exert cytotoxic effects. However, upon exposure to PLGA NPs, DCs showed phenotypes and cytokine secretion profiles consistent with maturation which resulted, at least in part, from the transient intracellular activation of mitogen-activated protein kinases (MAPKs). Interestingly, NP-specific stimulation patterns were observed since NP surface properties had a sensible influence on the various parameters measured.     

Pharmacokinetic and pharmacodynamic profiles of recombinant human erythropoietin-loaded poly(lactic-co-glycolic acid) microspheres in rats

Aim:

To characterize the pharmacokinetic and pharmacodynamic profiles of the recombinant human erythropoietin (rhEPO)-loaded poly(lactic-co-glycolic acid) (PLGA) microspheres in rats.

Methods:

The rhEPO-loaded microspheres were prepared using a solid-in-oil-in-water emulsion method. Pharmacokinetics and pharmacodynamics of the rhEPO-loaded microspheres were evaluated in male Sprague-Dawley rats. The serum rhEPO level was determined with ELISA. The level of anti-rhEPO antibody in the serum was measured to assess the immunogenicity of rhEPO released from the microspheres.

Results:

rhEPO was almost completely released from the PLGA microspheres in vitro, following zero-order release kinetics over approximately 30 d. After intramuscular injection (10 000 or 30 000 IU rhEPO/kg) in the rats, the serum rhEPO concentration reached maximum levels on d 1, then decreased gradually and was maintained at nearly steady levels for approximately 4 weeks. Furthermore, the release of rhEPO from the PLGA microspheres was found to be controlled mainly by a dissolution/diffusion mechanism. A good linear correlation (R²=0.98) was obtained between the in vitro and in vivo release data. A single intramuscular injection of the rhEPO-loaded PLGA microspheres (10 000 or 30 000 IU rhEPO/kg) in the rats resulted in elevated hemoglobin and red blood cell concentrations for more than 28 d. Moreover, the immunogenicity of rhEPO released from the PLGA microspheres was comparable with that of the unencapsulated rhEPO.

Conclusion:

The results prove the feasibility of using the PLGA-based microspheres to deliver rhEPO for approximately 1 month.     

Release of Human Serum Albumin from Poly(lactide-co-glycolide) Microspheres

Human serum albumin (HSA) was encapsulated in a 50:50 copolymer of DL-lactide/glycolide in the form of microspheres. These microspheres were used as a model formulation to study the feasibility of controlling the release of large proteins over a 20- to 30-day period. We show that HSA can be successfully incorporated into microspheres and released intact from these microspheres into various buffer systems at 37°C. A continuous release of the protein could be achieved in physiological buffers at 37°C over a 20- to 30-day period from microspheres with high protein loadings (11.6%). These results demonstrate the potential of poly(DL-lactide-co-glycolide) microspheres for continuous delivery of large proteins.     

重组人生长激素缓释微球.Ⅰ.制备与体外释放研究

采用复乳-溶媒蒸发法制备重组人生长激素（rhGH）可生物降解缓释微球，考察蛋白稳定剂泊洛沙姆407（F127）对rhGH体外释放的影响。利用均匀设计优化微球的处方和制备工艺，制得的rhGH-PLGA微球球形圆整，表面光滑致密，粒径均匀且具有较高的包封率和载药量。微球的体外释药行为呈先快后慢的两相释放模式，d30时含有F127的微球累积释药量约79％，较不含稳定剂的微球高22％。表明F127可通过抑制有机溶剂诱导的蛋白聚集而对rhGH起到稳定作用。     

重组人生长激素治疗儿童生长激素缺乏症的临床观察

目的：探讨重组人生长激素（rhGH）对生长激素缺乏症（GHD）患儿的治疗效果及对甲状腺功能、血清胰岛素生长因子-1（IGF-1）、25羟维生素D（25（OH）D）水平的影响。方法：选取我院2013年1月至2017年12月我院门诊治疗的70例GHD患儿作为试验组,另外选取70名同龄健康儿童作为对照组,试验组采用rhGH治疗,分析试验组在治疗6个月、治疗12个月后的身高、身高标准差积分、生长速率、骨龄/实际年龄,检测试验组治疗前及治疗12个月后的血清游离三碘甲状腺原氨酸（FT3）、游离甲状腺激素（FT4）、促甲状腺激素（TSH）、IGF-1、25（OH）D水平,并与对照组进行比较。结果：在治疗6个月、12个月后,试验组患儿的身高、身高标准差积分、生长速率、骨龄/实际年龄测定值较治疗前均显著的增加,差异有统计学意义（P<0.05）;在治疗12个月后,试验组患儿的血清FT3、IGF-1、25（OH）D水平升高,差异具有统计学意义（P<0.05）,对照组的血清FT3高于试验组治疗前水平（P<0.05）,对照组的血清IGF-1、25（OH）D高于试验组治疗前及治疗后的水平（P<0.05）。结论：rhGH对GHD患儿的治疗效果显著,能明显改变患儿FT3、血清IGF-1、25（OH）D水平。     

重组人生长激素治疗特发性身材矮小患儿的疗效评价

目的:重组人生长激素(rhGH)为基因工程大肠杆菌或哺乳动物细胞产生的人生长激素,其结构和氨基酸排序与人垂体激素雷同,本文评价其治疗特发性身体矮小患者的疗效与安全性.方法:查阅国内外近期相关文献,并结合笔者临床经验进行综述.结果与结论:尽管疗效研究组为重组人生长激素可改善特发性身材矮小患儿的最终身高,但临床上尚有争议,尤其是诊断内源性生长激素缺乏仍是尚待突破的课题.     

超氧化物歧化酶乳酸-羟乙酸共聚物微球的制备及其性质

利用复乳溶剂挥发法制备了超氧化物歧化酶（SOD）的乳酸－羟乙酸共聚物（PLGA）微球，考察了各工艺因素对微球粒径、包封率等的影响，通过扫描电子显微镜（SEM）、差示扫描量热分析（DSC）初步研究了其性质，结果表明，通过调整内水相的体积及浓度，分散相体积及PH值，可得到较高包封率，粒径在20－30μm，形态圆整，表面多孔的SOD微球，DSC表明SOD被有效地包入了PLGA微球中。     

Visual Evidence of Acidic Environment Within Degrading Poly(lactic-co-glycolic acid) (PLGA) Microspheres

Purpose. In the past decade, biodegradable polymers have becomethe materials of choice for a variety of biomaterials applications. Inparticular, poly(lactic-co-glycolic acid) (PLGA) microspheres havebeen extensively studied for controlled-release drug delivery. However,degradation of the polymer generates acidic monomers, andacidification of the inner polymer environment is a central issue in thedevelopment of these devices for drug delivery. Methods. To quantitatively determine the intrapolymer acidity, weentrapped pH-sensitive fluorescent dyes (conjugated to 10,000 Dadextrans) within the microspheres and imaged them with confocalfluorescence microscopy. The technique allows visualization of thespatial and temporal distribution of pH within the degradingmicrospheres (1). Results. Our experiments show the formation of a very acidicenvironment within the particles with the minimum pH as low as 1.5. Conclusions. The images show a pH gradient, with the most acidicenvironment at the center of the spheres and higher pH near the edges,which is characteristic of diffusion-controlled release of the acidicdegradation products.