聚乳酸分子量对利福平聚乳酸微球性质的影响

目的 :考察聚乳酸分子量对利福平聚乳酸微球性质的影响。方法 :采用分散一溶媒扩散法制备利福平聚乳酸微球 ,测定微球的粒径分布和包封率 ,进行体外释药和稳定性试验。结果 :在本制备方法中 ,聚乳酸分子量对微球粒径分布的影响作用不明显 ;药物包封率随聚乳酸分子量增大而增加 ;聚乳酸分子量减小 ,微球体外释药速度加快。稳定性试验表明 ,微球在 4℃和室温 (2 0～ 2 5℃ )条件下性质稳定 :3 7℃条件下因聚乳酸软化 ,微球发生粘连聚集。结论 :应根据实验目的选择适宜分子量的聚乳酸 ,以获得所需性质的微球。     

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。     

辛伐他汀聚乳酸微球的制备及药剂学性质

目的:制备辛伐他汀聚乳酸微球,并考察其药剂学性质.方法:采用乳化挥发法制备辛伐他汀聚乳酸微球,用光学显微镜考察微球的粒径,用扫描电镜观察微球的形状和表面形态,用差示扫描量热法(DSC)和红外光谱法研究药物在载体中的分散状态及相互作用.结果:辛伐他汀聚乳酸微球的算术平均粒径为(42.1±2.3)μm(n=500),载药量为(22.4±0.3)%(n=3),药物包封率为(80.7±0.6)%(n=3).37℃时2种相对分子质量的聚乳酸(10 000和20 000)制备的微球体外累积释药量分别为92.68%和84.07%,释药动力学符合Higuchi方程.结论:辛伐他汀聚乳酸微球具有很好的缓控释能力.     

氟维司群PLA-block-mPEG微球在大鼠体内的药动学研究

分别以嵌段共聚物(聚乳酸-单甲氧基聚乙二醇,分子量比为40 000:2 000)和非嵌段共聚物(聚乳酸-聚羟乙酸,分子量均为40 000,摩尔比分别为75:25、50:50)作为载体材料,采用乳化-液中干燥法制备包载氟维司群的微球.大鼠单剂量(50 mg/kg)皮下注射3种氟维司群微球,采用LC-MS/MS法测定血药浓度,计算药动学参数.结果表明,使用嵌段共聚物制备的微球,药-时曲线较平稳,释放效果较好.     

聚(ε-己内酯) -聚乙二醇-聚(ε-己内酯)两亲三嵌段共聚物蛋白大分子药物微球的研究

目的:研究以聚(ε-己内酯) -聚乙二醇-聚(ε-己内酯) (PCE)制备蛋白大分子药物微球的方法及其与成品理化性质和释放动力学的关系。方法:采用复乳溶剂挥发法制备牛血清白蛋白(BSA) PCE微球,以扫描电镜观察微球的表面形态,以Mi-croBCA法测定微球载药量和包封率,以累积释放量考察微球体外释药特性。结果:微球外形圆整、表面光滑。不同分子量PCE微球载药量和包封率相近,但体外释药特性显著不同,释放机制为扩散-降解,其中PCE4000因扩散作用释出的蛋白量明显低于其它分子量所制微球。微球体外释药规律符合扩散-溶蚀(Q=k1t1/2+k2t+k3t2+k4t3)(r=0.997)方程。结论:以PCE制备蛋白大分子药物微球具有良好的缓释效果,突释小,释放完全。     

红霉素聚乳酸微球制备工艺的研究

目的 :通过正交设计筛选出制备红霉素聚乳酸微球的最佳工艺。方法 :用正交实验设计优化红霉素聚乳酸微球制备工艺 ,用扫描电子显微镜观察微球表面形态 ,差示扫描热分析确证含药微球的形成 ,及所制备的红霉素聚乳酸微球的平均粒径、粒度分布 载药量 包封率 工艺重现性进行了研究。结果 :红霉素聚乳酸微球的形态圆整 ,且药物确已被包裹在微球中 ,而非机械混合 ,微球的平均粒径为 10 .98± 0 .15mm ,粒径在 5～ 2 0mm占总数的 94 %以上 ,载药量为 2 4 .16 %± 0 .5 1,包封率为 6 3.5 4 %± 0 .5 8,最佳工艺条件重现性良好。结论 :本研究获得了制备红霉素聚乳酸微球较满意的工艺     

尼莫地平聚乳酸缓释微球的制备及其药剂学性质

目的制备尼莫地平聚乳酸缓释微球,并对其药剂学性质进行研究.方法采用溶剂蒸发萃取法制备微球,正交实验设计考察影响制备工艺的因素,用扫描电镜观察微球表面形态,红外光谱分析验证舍药微球的形成,对制备的尼莫地平微球的粒径、栽药量、包封率等性质及体外释放特性进行了研究.结果尼莫地平聚乳酸微球的最佳制备工艺稳定,微球形态圆整,粒径分布适宜,药物确已被包裹于微球中.优化工艺制得的微球平均粒径为(61.7±0.46)μm,载药量为(53.2±0.8)%,包封率为(86.2±0.6)%,体外释放符合Higuchi方程,Q=17.708t1/2-0.975 8(r=0.995 4),t1/2=8.29 d.结论本实验获得了较理想的尼莫地平聚乳酸微球,其体外释药特性符合长效制剂特征.     

甲睾酮聚乳酸微球的制备及其释药性能研究

目的制备甲睾酮聚乳酸微球,研究其体外释药过程。方法采用乳化-溶剂挥发法制备甲睾酮聚乳酸微球;以0.25%SDS-5%乙醇(pH3.4)为释放介质,采用高效液相色谱法测定甲睾酮聚乳酸微球的体外释药量。结果甲睾酮聚乳酸微球开始释药较快,存在一定突释效应,随后以缓慢的方式释药,可用双相动力学方程100-R=35.77e0.1321t+63.91e7.372E-4t描述。结论制成的甲睾酮聚乳酸微球具有明显的缓释作用。     

微球中聚乳酸羟基乙酸共聚物浓度与微球结构、释药、降解的关系研究

目的:研究微球中聚乳酸羟基乙酸共聚物(PLGA)浓度与微球结构、释药、降解的关系。方法:以牛血清白蛋白(BSA)为药物,采用复乳法制备PLGA浓度分别为10%、15%、20%的BSA-PLGA微球,以包封率、载药量、粒径为指标考察PLGA浓度对3种微球性质的影响;采用扫描电子显微镜观察3种微球和降解40 d内的外观和内部形态;使用荧光蛋白-异硫氰酸荧光素牛血清白蛋白代替BSA作为模型药物制备PLGA微球,并采用激光共聚焦显微镜观察荧光蛋白在微球骨架内的分布情况;采用BCA法考察3种微球的体外释药情况;采用压汞仪考察降解28 d内20%PLGA所制微球的孔径、孔隙率、截面孔隙率的变化;采用凝胶渗透色谱法检测10%、20%PLGA所制微球降解28 d内分子质量及其降解模型拟合。结果:与10%、15%PLGA所制微球比较,20%PLGA所制微球的包封率[(81.96±1.84)%]和粒径[(139.50±0.21)μm]最大,载药量[(7.28±0.45)%]最低,截面孔隙率[(32.35±1.98)%]和孔径[(12.43±0.14)μm]最小,释药突释率最低,40 d内的释放速率相对较慢,降解后截面孔隙率最大,降解均遵循假一级模式(r2=0.065 3)。结论:在考察范围内,随着PLGA浓度的增加,微球的结构更致密,释药更平稳,降解更易形成中空结构。     

W/O法制备盐酸土霉素/聚乳酸微球及其释药性能

目的制备一种可作药用的长效缓释微球。方法以盐酸土霉素为囊心物质用W／O溶剂挥发法制备了盐酸土霉素／聚乳酸微球，讨论了不同制备条件对聚乳酸栽药微球的影响，并且分析了药物含量、聚乳酸分子量、微球粒径等条件对栽药聚乳酸微球释放性能的影响。结果所制得的微球较为规则，包封率较高，释药时间能长达半个月以上。结论聚乳酸能够作为一般的水溶性药物的长效释放基材。     

米托蒽醌聚乳酸缓释毫微粒冻干针剂的体外释药特性研究

选择含1％维生素C的生理盐水作释药介质，用动态透析系统和分光光度法考察了不同分子量聚乳酸毫微粒冻干针剂的体外释药特性。高分子量聚乳酸毫微粒的释药速度明显慢于低分子量的聚乳酸毫微粒。通过选择适宜分子量的聚乳酸制备毫微粒可控制其释药速度。     

Degradation of DL-PLA-methadone microspheres during in vitro release

The in vitro degradation of polylactic acid of different weight average molecular weight (M_w) in microspheres containing variable amounts of methadone base (between 17 and 47%) was studied using the degradation index (DI), polidispersivity (pd) and molecular weights distribution. Both pd and DI are independent of initial methadone content and increase with M_w polymer, showing values of DI around 6.6 for the high M_w and 2.9 for the lower M_w. The distribution functions in the number of the molecular weights during the degradation assays indicate the presence of different break mechanisms for high and low molecular weight chains. A semiempiric model is proposed to explain the evolution of M_n during degradation in function of the number of bonds available for their breaking and hydrolysis rate constant. The first parameter ranges between 2.35 and 6.65 in function of M_w; the hydrolysis rate constant is independent of M_w and equal to 0.020 h⁻¹ (SD = 0.011 h⁻¹).     

Pharmacokinetics and in vitro and in vivo correlation of huperzine A loaded poly(lactic-co-glycolic acid) microspheres in dogs

The purpose of this study was to investigate the pharmacokinetics and in vitro/in vivo correlation (IVIVC) of huperzine A loaded poly(lactic-co-glycolic acid) (PLGA) microspheres in dogs. Several huperzine A loaded PLGA microspheres were prepared by an O/W method and three of them (single dose) were injected intramuscularly (i.m.) or subcutaneously (s.c.) to five beagle dogs, respectively. With the increase of the molecular weight of PLGA and the particle size of microspheres, the in vitro and in vivo release periods of huperzine A were prolonged. After s.c. injection, the release of huperzine A from microspheres was faster than that after i.m. injection. The IVIVC models of huperzine A loaded PLGA microspheres were established successfully and after i.m. administration the linear relationship between the in vitro and the in vivo releases was better than that after s.c. administration. It was also found when the particle size of the microspheres was smaller; the values of correlation coefficient were higher.     

Chitosan/cellulose acetate microspheres preparation and ranitidine release in vitro

New microspheres containing hydrophilic core and hydrophobic coating as a controlled-release system with no toxic reagents were proposed. Water in oil in water (W/O/W) emulsion and solvent evaporation methods were used to make chitosan/ cellulose acetate (CCA) microspheres sized 200 - 400 microm. Ranitidine hydrochloride, as a model drug, was investigated for its release properties in vitro. The loading efficiency and release rate of ranitidine were affected by chitosan concentration and molecular weight. Higher loadings were obtained at lower concentrations in the interval of 1% to 2%. With chitosan at a 2% concentration microspheres could be obtained with more spherical appearance, smaller size, and higher ranitidine loading efficiency microspheres than at other concentrations. Among the different molecular weight chitosan (47, 145, 308, 499, and 1130 KD) microspheres, the high molecular weight chitosan (1130 KD) microspheres had relatively high loading efficiency (10%). Molecular weight and concentration of chitosan as well as the size of microspheres affected the release of ranitidine. Microspheres smaller than 280 microm released the drug faster than did the bigger by about 10%. The optimal condition for the preparation of the microspheres was chitosan concentration 2%, molecular weight 1130 KD. The ranitidine release from the microspheres was 30% during 48 h in phosphate-buffer saline medium.     

Polymer and microsphere blending to alter the release of a peptide from PLGA microspheres.

The objective of this study was to evaluate the effect of polymer and microsphere blending in achieving both a sufficient initial release and a desired continuous release of a peptide from poly(D, L-lactide-co-glycolide) microspheres. Leuprolide acetate loaded hydrophilic 50:50 PLGA microspheres were prepared by a solvent-extraction/evaporation process and were characterized for their drug load, bulk density, size distribution, surface area, surface morphology, in vitro drug release, and in vivo efficacy. Combining PLGA polymers that varied in their molecular weights in various ratios yielded microspheres with varied drug release profiles commensurate with the hydration tendencies of the polymers. Increasing the component of lower molecular weight 50:50 hydrophilic PLGA polymer, 8.6 kDa increased the initial drug release. A similar microsphere formulation prepared instead with blending microspheres from individual polymers showed a similar increase. In an animal model, microspheres obtained from polymer or microsphere blends attained a faster onset of testosterone suppression as compared to microspheres from higher molecular weight 50:50 hydrophilic PLGA polymer, 28.3 kDa, alone. These studies illustrated the feasibility of blending polymers or microspheres of varied characteristics in achieving modified drug release. In particular the increased initial release of the peptide could help avoid the therapeutic lag phase usually observed with microencapsulated macromolecules.     

Degradation of multi-phase microspheres fabricated via solvent removal

Multi-phase polymer microspheres for drug encapsulation have been fabricated via solvent removal using poly(-lactic) acid (PLLA) and poly(fumaric-co-sebacic) anhydride (20:80) (P(FA:SA) (20:80)). The process by which these spheres degrade was investigated. Characterization was conducted to determine the extent of degradation of the two polymer phases over 16 weeks using scanning-electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), gel-permeation chromatography (GPC), differential-scanning calorimetry (DSC) and nuclear magnetic resonance (NMR). These experiments showed that the P(FA:SA) (20:80) phase of the multi-phase microspheres degraded faster than the PLLA phase, leaving only some of the poly(sebacic) oligomers after 16 weeks in both the in vitro and in vivo studies. These portions could remain because they were entrapped in the PLLA phase, preventing more rapid degradation. The PLLA phase showed minimal changes over the 16 week period; there was no significant change in crystallinity and only a small decrease in molecular weight in both the in vitro and in vivo studies. The in vitro study showed a rapid mass loss initially (first 3 days), followed by a fairly constant mass through 16 weeks, while the in vivo study showed a mass gain due to tissue influx.     

骨载异烟肼缓释微球的制备及其在动物模型中的释放研究

目的：观察探讨骨载异烟肼聚乳酸微球的设计和制备方法及其在动物模型中的释放效果。方法：选择24只雄性新西兰大白兔作为实验动物模型,采用复乳法制备缓释微球,对微球进行形态学观察、粒径分布观察、体内释药和体外释药观察。结果：平均微球粒径（10.59±0.3）μm,平均包封率（44.9±0.9）%,平均载药率（13.0±0.6）%。在24h、72h、1w、3w微球组滑膜药物浓度明显高于口服组和原药组,P＜0.05。与口服组和原药组对比,微球组0～24h药物波动差值明显更低,P＜0.05。结论：本研究制备的骨载异烟肼缓释微球具有良好的缓释性,能够在抗结核治疗中置入骨结核病灶对术后病灶发挥持久的疗效。