氟脲嘧啶白蛋白微球的体外释放

本文报告了氟脲嘧啶白蛋白微球的体外释放特性。结果表明微球固化温度影响其释放速率。１００℃制备的微球释放最快，１８０℃制备微球释放最慢，二者相差几乎一倍。１５０℃制备的微球其释放速度介于二者之间。     

芹菜素壳聚糖微球的制备及体外释药研究

目的以芹菜素为模型药物、脱乙酰壳聚糖为药物载体,制备芹菜素壳聚糖微球,并测定微球中芹菜素的体外释放度。方法采用复乳-乳化化学交联法制备微球,正交试验优化微球制备的工艺,高效液相色谱法检测芹菜素含量。结果最佳工艺制备4批微球,形态良好,微球圆整,平均载药量为8.54%,平均包封率为69.69%,平均粒径为84.33μm。微球在pH 6.8和pH 7.4的磷酸盐缓冲液中释放36 h。结论所选制备工艺稳定,适用于芹菜素壳聚糖微球的制备,体外药物释放结果显示,微球具有良好的缓释效果。     

双氯芬酸钠海藻酸钙凝胶微球的制备及其性质分析

目的制备双氯芬酸钠海藻酸钙凝胶微球，并对凝胶微球的性质进行分析。方法采用滴制法制备双氯芬酸钠海藻酸钙凝胶微球，紫外分光光度法测定药物的含量，对凝胶微球的粒度、圆整度、休止角和堆密度进行测定，并用扫描电镜观察凝胶微球的形态。结果制备的双氯芬酸钠海藻酸钙凝胶微球包封率较高，粉体学性质良好，球形均匀圆整。结论该方法适用于双氯芬酸钠海藻酸钙凝胶微球的制备。     

盐酸尼卡地平鼻粘膜用明胶微球的工艺研究

目的研究盐酸尼卡地平鼻粘膜用明胶微球的制备工艺。方法以天然可生物降解的明胶为载体材料 ,液体石蜡为油相 ,Span80为乳化剂 ,采用正交设计优化空白明胶微球制备工艺 ,用乳化法和吸附法制备了盐酸尼卡地平明胶微球。采用溶媒提取法利用HPLC测定微球中药物含量。结果所得明胶微球形态良好 ,粒径分布窄 ,所选择的HPLC法用于测定明胶微球中药物含量回收率及重现性均较好 ,乳化法制备明胶微球的包封率为 31 3% ,吸附法为 5 1 %。结论所优化制备工艺可用于盐酸尼卡地平鼻粘膜给药明胶微球的制备。     

硫酸长春碱乳酸-羟基醋酸共聚物微球的处方和制备工艺研究

目的：制备硫酸长春碱生物可降解注射微球，考察处方和制备工艺对微球包封率及释放度的影响。方法：以乳酸-羟基醋酸共聚物（PLGA）为载体材料，分别采用O／O型和W／O／W乳化溶剂挥发法制备微球。结果：采用O／O型乳化溶剂挥发法制备的微球表面光滑无孔洞，内部结构致密；W／O／W型微球表面有较多皱褶，内部结构多孔。采用O／O型乳化溶剂挥发法制备的微球包封率在70％左右，明显高于W／O／W型乳化溶剂挥发法制备的微球，释药速度明显低于第2种方法制备的微球。采用O／O型乳化溶剂挥发法，以PLGA（50：50．10000）制备的微球在体外可持续释药21d以上。结论：硫酸长春碱PLGA微球的制备工艺可行，缓释特征明显，无突释效应。     

蛋白微球机械剪切制备方法的研究

目的  建立制备蛋白微球的机械剪切法。方法  在不同工作条件下制备蛋白微球,通过检测微球大小、稳定性及其他质量指标来确定最佳工作条件。结果  当将起始制备温度设定为65 ℃、转定子转速调至15 000 rpm时,机械剪切法可制备最稳定、质量最佳的蛋白微球,且可获得最高蛋白微球产量。结论  机械剪切法可用于蛋白微球的规模化生产。     

双氯芬酸钠明胶微球的制备及体内外释药的研究

目的将双氯芬酸钠制备成明胶微球,考察其缓释效果。方法采用单凝聚法制备双氯芬酸钠明胶微球,并对微球的体内外释药进行考察。结果制备的微球粒径范围为48～100μm,平均粒径为70.70±11.29μm,载药量为35%。体内外释药实验结果表明双氯芬酸钠明胶微球有缓释作用。结论本法制备的双氯芬酸钠明胶微球能够起到明显缓释作用。     

姜黄素多孔淀粉微球的制备

目的 制备姜黄素多孔淀粉微球.方法 用酶解法在玉米淀粉粒上水解出小孔,利用多孔淀粉的吸附作用制备姜黄素淀粉微球.结果 微球形态圆整,孔隙发育良好,载药量达4.1mg·g-1.结论 本法制备微球简单,方便.     

利培酮长效注射微球的制备及体外释放的研究

目的：制备利培酮长效注射微球并考察其体外释放行为。方法：使用乳酸-羟基乙酸共聚物（PLGA）为材料,采用乳化-溶剂挥发法制备利培酮微球,观察微球的形态及粒径,测定微球的载药量和包封率,考察微球的体外释放情况。结果：利培酮微球表面圆整,粒径集中在40～80μm之间。微球的包封率较高,达到80％以上,以低分子量PLGA（50：50）制备的微球,体外突释很高达到40％以上;以高分子量PLGA（75：25）制备的微球,在高载药量时突释较小,可持续释放达3周以上。结论：以高分子量PLGA制备的高载药量的利培酮微球,体外突释较小可缓释达3周以上。     

骨炎一号聚乳酸微球的研制

目的 筛选制备骨炎一号聚乳酸微球的最佳工艺。方法 复乳-溶剂挥发法(W／O／W-liquid drying process)制备骨炎一号聚乳酸微球。通过正交实验设计优化骨炙一号聚乳酸微球制备工艺，用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，及对所制备微球的平均粒径、载药量、包封率、工艺重现性进行了研究。结果骨炎一号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8．59μm，粒径在1～12μm左右的占总数的90%以上，载药量为48．39%，包封率为19．32％。结论得到了骨炎一号聚乳酸微球较满意的制备工艺。     

Preparation and in vitro evaluation of Eudragit microspheres containing acetazolamide

The aim of this study was to prepare and evaluate Eudragit (RS and RL) microspheres containing acetazolamide. Microspheres were prepared by solvent evaporation method using acetone/liquid paraffin system. The influence of formulation factors (stirring speed, polymer:drug ratio, type of polymer, ratio of the combination of polymers) on particle size, encapsulation efficiency and in vitro release characteristics of the microspheres were investigated. The yields of preparation and the encapsulation efficiencies were high for all formulations the microspheres were obtained. Mean particle size changed by changing the polymer:drug ratio or the stirring speed of the system. Although acetazolamide release rates from Eudragit RS microspheres were very slow and incomplete for all formulations, they were fast from Eudragit RL microspheres. When Eudragit RS was added to Eudragit RL microsphere formulations, release rates slowed down and achieved the release profile suitable for peroral administration.     

Preparation and characterization of drug-loaded polymethacrylate microspheres by an emulsion solvent evaporation method

Microspheres containing the anti-hypertension drug, felodipine, were prepared by the emulsion solvent evaporation method (o/o) using acrylate methacrylate copolymers, Eudragit RL PO and Eudragit RS PO, as wall materials. In order to increase the encapsulation efficiency, a mixed solvent system comprising 1:1 proportions of acetonitrile and dichloromethane was used as a dispersed phase. The morphology of the microspheres was evaluated using a scanning electron microscope, which showed a spherical shape with smooth surface. The mean sphere diameter was between 9.5-13.2 microm and the microencapsulation efficiencies ranged from 51.4-80.4%. The release profiles and encapsulation efficiencies depended strongly on the structure of the polymers used as wall materials. The release rate of the Eudragit RS PO microspheres was much lower than that of Eudragit RL PO microspheres. Whereas Eudragit RL PO microspheres followed the Higuchi rule, Eudragit RS PO microspheres exhibited a triphasic release profile. It is concluded that drug release rate can be controlled by choice of polymer type.     

Design and in vitro evaluation of gentamicin-Eudragit microspheres intended for intra-ocular administration

The conditions of preparation of gentamicin sulfate microspheres with high drug loading and a particle size less than 5 micro m, using a double-emulsion-solvent evaporation technique, intended for intra-ocular administration are described. The microspheres were prepared from poly methacrylate (Eudragit RS and RL) polymers cross-linked with polyvinyl alcohol. The parameters that improved the incorporation efficiency of gentamicin in the microspheres and controlled the particle size and surface morphology were investigated. Modifying the secondary aqueous phase by partially saturating it with various concentrations of either KCl or gentamicin increased the incorporation efficiency of the drug and affected the mean diameters of the microspheres. However, these characteristics were not altered when the initial drug loading was increased in the formulations. The modified gentamicin microspheres exhibited a smooth surface with an incorporation efficiency rate of 12.59% and a mean diameter of 4.06 micro m. The antimicrobial efficiency of gentamicin released from the modified particles against selected Gram-positive and -negative organisms including Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa confirmed that the entrapped gentamicin seemed to remain unaltered by the encapsulation process.     

Preparation and in vitro dissolution profile of zidovudine loaded microspheres made of Eudragit RS 100, RL 100 and their combinations

The objective of present investigation was to evaluate the entrapment efficiency of the anti-HIV drug, zidovudine, using two Eudragit polymers of different permeability characteristics and to study the effect of this entrapment on the drug release properties. In order to increase the entrapment efficiency optimum concentration of polymer solutions were prepared in acetone using magnesium stearate as droplet stabilizer. The morphology of the microspheres was evaluated using a scanning electron microscope, which showed a spherical shape with smooth surface. The mean sphere diameter was between 1000-3000 microm and the entrapment efficiencies ranged from 56.4-87.1%. Polymers were used separately and in combination to prepare different microspheres. The prepared microspheres were studied for drug release behavior in phosphate buffer at pH 7.4, because the Eudragit polymers are independent of the pH of the dissolution medium. The release profiles and entrapment efficiencies depended strongly on the structure of the polymers used as wall materials. The release rate of zidovudine from Eudragit RS 100 microspheres was much lower than that from Eudragit RL 100 microspheres. Evaluation of release data reveals that release of zidovudine from Eudragit RL 100 microspheres followed the Higuchi rule, whereas Eudragit RS 100 microspheres exhibited an initial burst release, a lag period for entry of surrounding dissolution medium into polymer matrix and finally, diffusion of drug through the wall material.     

Effects of the permeability characteristics of different polymethacrylates on the pharmaceutical characteristics of verapamil hyhdrochloride-loaded microspheres

Microspheres containing verapamil hydrochloride (VRP) were prepared with various polymethacrylates, with different permeability characteristics (Eudragit RS 100, Eudragit RL 100, Eudragit L 100 and Eudragit L 100-55) and also with mixtures of these polymers in a 1:1 ratio using the solvent evaporation method. The aim was to investigate the effects of the permeability of the polymers on drug release rates and the characteristics of the microspheres. To achieve these aims, yield, incorporation efficiency, particle size and the distribution of microspheres were determined, and the influence of the inner phase viscosities prepared with different polymer and polymer mixtures on particle size and the distribution of microspheres were evaluated. Surface morphologies of microspheres were observed by scanning electron microscope. Drug release rates from microspheres were determined by the half-change method using a flow-through cell. The results indicate that microspheres with different surface morphologies and statistically different yields and incorporation efficiencies could be prepared and their particle size and distribution xariances resulted from the viscosity of the inner phase. Dissolution profiles showed that the drug release rate could be modified depending on the permeability characteristics of polymethacrylates.     

Effects of the permeability characteristics of different polymethacrylates on the pharmaceutical characteristics of verapamil hyhdrochloride-loaded microspheres

Microspheres containing verapamil hydrochloride (VRP) were prepared with various polymethacrylates, with different permeability characteristics (Eudragit RS 100, Eudragit RL 100, Eudragit L 100 and Eudragit L 100-55) and also with mixtures of these polymers in a 1:1 ratio using the solvent evaporation method. The aim was to investigate the effects of the permeability of the polymers on drug release rates and the characteristics of the microspheres. To achieve these aims, yield, incorporation efficiency, particle size and the distribution of microspheres were determined, and the influence of the inner phase viscosities prepared with different polymer and polymer mixtures on particle size and the distribution of microspheres were evaluated. Surface morphologies of microspheres were observed by scanning electron microscope. Drug release rates from microspheres were determined by the half-change method using a flow-through cell. The results indicate that microspheres with different surface morphologies and statistically different yields and incorporation efficiencies could be prepared and their particle size and distribution variances resulted from the viscosity of the inner phase. Dissolution profiles showed that the drug release rate could be modified depending on the permeability characteristics of polymethacrylates.     

Effect of formulation variables on in vitro drug release and micromeritic properties of modified release ibuprofen microspheres

Modified release microspheres of the non-steroidal anti-inflammatory drug, ibuprofen, were formulated and prepared using the emulsion solvent diffusion technique. The contribution of various dispersed phase and continuous phase formulation factors on in vitro drug release and micromeritic characteristics of microspheres was examined. The results demonstrated that the use of Eudragit RS 100 and Eudragit RL 100 as embedding polymers modified the drug release properties as a function of polymer type and concentration. Eudragit RS 100 retarded ibuprofen release from the microspheres to a greater extent than Eudragit RL 100. The drug/polymer concentration of the dispersed phase influenced the particle size and drug release properties of the formed microspheres. It was found that the presence of emulsifier was essential for microsphere formation. Increasing the concentration of emulsifier, sucrose fatty acid ester F-70, decreased the particle size which contributed to increased drug release properties. Scanning electron microscopy revealed profound distortion in both the shape and surface morphology of the microspheres with the use of magnesium stearate as added emulsifier. The application of an additional Eudragit RS 100 coat onto formed microspheres using fluid bed technology was successful and modulated the drug release properties of the coated microspheres.     

Effect of formulation variables on in vitro drug release and micromeritic properties of modified release ibuprofen microspheres.

Modified release microspheres of the non-steroidal anti-inflammatory drug, ibuprofen, were formulated and prepared using the emulsion solvent diffusion technique. The contribution of various dispersed phase and continuous phase formulation factors on in vitro drug release and micromeritic characteristics of microspheres was examined. The results demonstrated that the use of Eudragit RS 100 and Eudragit RL 100 as embedding polymers modified the drug release properties as a function of polymer type and concentration. Eudragit RS 100 retarded ibuprofen release from the microspheres to a greater extent than Eudragit RL 100. The drug/polymer concentration of the dispersed phase influenced the particle size and drug release properties of the formed microspheres. It was found that the presence of emulsifier was essential for microsphere formation. Increasing the concentration of emulsifier, sucrose fatty acid ester F-70, decreased the particle size which contributed to increased drug release properties. Scanning electron microscopy revealed profound distortion in both the shape and surface morphology of the microspheres with the use of magnesium stearate as added emulsifier. The application of an additional Eudragit RS 100 coat onto formed microspheres using fluid bed technology was successful and modulated the drug release properties of the coated microspheres.     

Design and in vitro evaluation of gentamicin–Eudragit microspheres intended for intra-ocular administration

The conditions of preparation of gentamicin sulfate microspheres with high drug loading and a particle size less than 5?µm, using a double-emulsion-solvent evaporation technique, intended for intra-ocular administration are described. The microspheres were prepared from poly methacrylate (Eudragit RS and RL) polymers cross-linked with polyvinyl alcohol. The parameters that improved the incorporation efficiency of gentamicin in the microspheres and controlled the particle size and surface morphology were investigated. Modifying the secondary aqueous phase by partially saturating it with various concentrations of either KCl or gentamicin increased the incorporation efficiency of the drug and affected the mean diameters of the microspheres. However, these characteristics were not altered when the initial drug loading was increased in the formulations. The modified gentamicin microspheres exhibited a smooth surface with an incorporation efficiency rate of 12.59% and a mean diameter of 4.06?µm. The antimicrobial efficiency of gentamicin released from the modified particles against selected Gram-positive and -negative organisms including Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa confirmed that the entrapped gentamicin seemed to remain unaltered by the encapsulation process.     

Design and evaluation of sustained release microspheres of potassium chloride prepared by Eudragit.

The aim of the present work was to prepare and evaluate the sustained release of potassium chloride formulations. Eudragit RS and/or RL loaded with potassium chloride microspheres were prepared by a solvent evaporation method. The effect of sustained release of Eudragit microspheres was evaluated by an in vitro dissolution test and in vivo oral absorption study, and the results were compared to a commercial product (Slow-K). The results showed that Eudragit microspheres loaded with potassium chloride can be easily prepared and satisfactory results obtained considering the size distribution and shapes of microspheres by incorporating aluminum stearate. The encapsulation efficiency and loading capacity were about 84-90% and 27%, respectively. Moreover, the Eudragit RS (30-45 mesh) and Eudragit RS/RL (20-30 mesh) microspheres showed a similar sustained release effect of commercial product via in vitro dissolution and in vivo oral absorption study.