巯基壳聚糖载胰岛素亚微球的制备及影响包封率的因素

目的制备巯基壳聚糖载胰岛素亚微球,并对影响包封率的因素进行考察。方法以三聚磷酸钠(TPP)为离子交联剂制备巯基壳聚糖载胰岛素亚微球。结果所制得的亚微球平均粒径为473.5nm,包封率为51.8%。结论亚微球的制备条件温和,快速简便。     

正交试验优选羧甲基壳聚糖-醋甲唑胺纳米微球的制备方案

目的：制备羧甲基壳聚糖载药纳米微球,醋甲唑胺为模型药物,测量药物的包封率和纳米微球形态.方法：采用乳化交联法,在微乳液的基础上制备载药纳米微球,对可能影响药物包封率的处方因素进行优化设计,筛选出最优配方.结果：羧甲基壳聚糖溶液的浓度对包封率有显著性影响,三聚磷酸钠溶液浓度和醋甲唑胺药量对包封率未见影响.优化方案的载药纳米微球包封率为49.36％,其电镜下为较规整的球型纳米微球,平均粒径386.0 nm.结论：采用乳化交联法,可形成较高包封率的羧甲基壳聚糖-醋甲唑胺纳米微球.     

磁性壳聚糖微球制备及生物相容性的研究

目的:制备5-氟尿嘧啶磁性壳聚糖微球并评价空载磁性壳聚糖微球的生物相容性。方法:采用乳化交联法制备5-氟尿嘧啶磁性壳聚糖微球并优化制备工艺,采用扫描电镜和振动样品磁强计(VSM)对微球进行表征;四噻唑蓝法观察细胞增殖情况,评估磁性壳聚糖微球的体外细胞毒性;溶血实验和血常规检查评估磁性壳聚糖微球的血液相容性;植埋实验评估磁性壳聚糖微球的组织相容性。结果:经过优化后的5-氟尿嘧啶磁性壳聚糖微球包封率和载药量分别为70.2%和12.3%,Z-均粒径为1 479.6 nm,饱和磁化度为4.79 emu.g-1,微球形态良好、均匀圆整;自制空载磁性壳聚糖微球体外细胞相容性符合要求,显示出良好的血液相容性和体内组织相容性。结论:优化了5-氟尿嘧啶磁性壳聚糖微球的制备工艺,制备的空载磁性壳聚糖微球具有很好的生物相容性。     

喷雾干燥法制备斑蝥素壳聚糖生物黏附微球的处方工艺研究

摘 要 目的：优选斑蝥素壳聚糖生物黏附微球的最佳处方工艺。方法: 采用喷雾干燥法制备微球,运用单因素试验考察不同壳聚糖分子量对微球胃黏膜黏附率的影响,不同药载比、壳聚糖醋酸溶液浓度和蠕动泵速度对斑蝥素包封率的影响。采用效应面法,以斑蝥素的包封率为考察指标,进一步优化药载比、壳聚糖醋酸溶液浓度和蠕动泵流速3个因素。结果: 斑蝥素壳聚糖生物黏附微球的最佳处方工艺为：斑蝥素和壳聚糖的重量比为19.83%,壳聚糖醋酸溶液浓度为0.77%,蠕动泵流速为9.225 ml·min-1。以最佳处方工艺制得的斑蝥素壳聚糖生物黏附微球包封率为90.14%。结论: 采用喷雾干燥法制备微球,具有工艺稳定、可重复等优点,制备的斑蝥素壳聚糖生物黏附微球具备较好的包封率和生物黏附性能。     

依托泊苷肺靶向壳聚糖微球的研制

目的:制备难溶性药物依托泊苷肺靶向壳聚糖微球,并对处方工艺进行筛选.方法:以壳聚糖为分散介质,采用乳化交联法制备依托泊苷肺靶向壳聚糖微球.结果:平均粒径为13.28μm,载药量为25.30%,药物包封率为43.51%.结论:制备的微球具有良好的缓释作用和靶向性.     

尼莫地平壳聚糖微球的制备及其体外释药特性的研究

目的 以壳聚糖为载体材料制备尼莫地平微球,并考察其体外释药特性。方法 以壳聚糖为载体,液体石蜡为油相,戊二醛为交联剂,span80为乳化剂,采用正交设计优化壳聚糖微球的制备工艺,用乳化交联法制备尼莫地平壳聚糖微球。模拟人体肠液的环境进行体外释药研究。结果 通过单因素考察和正交实验,筛选出尼莫地平壳聚糖微球的优化制备工艺和处方,所得微球形态圆整,大小均匀,表面光滑,平均粒径为9.56 μm,载药量为17.82%,包封率为52%。体外释药结果表明,一级动力学方程能较好的对其进行拟合。结论 尼莫地平壳聚糖微球的制备工艺稳定可行,所得壳聚糖微球有良好的缓释效果。     

尼莫地平壳聚糖微球的制备及其体外释药特性的研究

目的以壳聚糖为载体材料制备尼莫地平微球,并考察其体外释药特性。方法以壳聚糖为载体,液体石蜡为油相,戊二醛为交联剂,span80为乳化剂,采用正交设计优化壳聚糖微球的制备工艺,用乳化交联法制备尼莫地平壳聚糖微球。模拟人体肠液的环境进行体外释药研究。结果通过单因素考察和正交实验,筛选出尼莫地平壳聚糖微球的优化制备工艺和处方,所得微球形态圆整,大小均匀,表面光滑,平均粒径为9.56μm,载药量为17.82%,包封率为52%。体外释药结果表明,一级动力学方程能较好的对其进行拟合。结论尼莫地平壳聚糖微球的制备工艺稳定可行,所得壳聚糖微球有良好的缓释效果。     

磁性壳聚糖微球的释药和靶向研究

目的：利用改变pH值法制备磁性壳聚糖微球,并对微球的载药量、缓释特性和磁靶向特性进行测试.方法：采用紫外光谱吸收法测定载药量,渗透袋扩散技术测试微球的释药速度,体外模拟法测定微球的磁靶向性.结果：载药量为37%,包封率62%.微球10h内药物释放约为75%,连续释放78h.外加磁场应在2000～3000Gs左右,施加时间在2h为宜.结论：使用改变pH值法制备的壳聚糖微球,具有较高的载药量和包封率,微球缓释效果明显,并实验测出了适合微球靶向控制的磁场施加方式.     

喷雾干燥法制备三七皂苷缓释微球

目的 制备三七皂苷缓释微球.方法 以壳聚糖、丙烯酸树脂为载体材料,采用喷雾干燥法制备三七皂苷缓释微球.以载药量和包封率为指标,采用均匀设计法优化处方.结果 所制三七皂苷缓释微球的外观圆整,平均粒径为11.80μm,包封率70.4%,载药量9.1%,在磷酸缓冲液中三七皂苷12 h释放缓慢、平稳,释放均遵循Weibull方程.结论 所制三七皂苷缓释微球符合预期,具有很好的缓释效果.     

载胰岛素壳聚糖-果胶微球的制备及性能研究

目的以壳聚糖与果胶为载体,三聚磷酸钠、氯化钙为固化剂,制备载胰岛素的壳聚糖-果胶微球,并对微球的基本性质、载药性能及成型机制进行考察。方法采用离子移变胶凝法制备载胰岛素的壳聚糖-果胶微球,采用高效液相色谱法测定包封率,以微球形态、粒径、包封率作为考察指标,进行处方工艺的单因素筛选。用差示扫描量热法与傅里叶变换红外光谱法对微球的成型机制进行初步探讨。初步考察了载胰岛素壳聚糖-果胶微球的体外释药行为。结果胰岛素在0.8～60μg.mL-1内呈现良好的线性,相关系数r=0.999 8。所制备的微球形态圆整,平均粒径为（38.06±3.89）μm,包封率为（44.06±1.63）%。由DSC图谱推断,形成微球时,壳聚糖与果胶之间发生了相互作用。微球的FTIR图谱中未出现新的特征峰,推断在形成微球时,壳聚糖、果胶、胰岛素之间未发生化学反应。初步考察了载胰岛素壳聚糖-果胶微球体外释药呈现明显的缓释作用。结论本法制备工艺简单,重复性好,所制备的胰岛素微球外观圆整,粒径大小分布较均匀,具有明显缓释作用,但包封率不够理想,尚需进一步提高。     

Controlled release chitosan microspheres of mirtazapine: In vitro and in vivo evaluation

The purpose of the study was to formulate and evaluate controlled release chitosan microspheres of mirtazapine (MTZ) to improve the bioavailability by altering the pharmacokinetic profiles of the drug. Chitosan microspheres were prepared to prolong the release of the drug into the systemic circulation. Microspheres were prepared by a single water in oil (w/o) emulsion technique varying the chitosan/drug ratio, stirring speed and concentration of the crosslinking agent (glutaraldehyde). Drug-polymer compatibility studies were carried out using fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The microspheres were evaluated for encapsulation efficiency, particle size, surface morphology, swelling index, in vitro release, as well as erosion and in vivo studies in rats. The FT-IR and DSC studies revealed no interaction between drug and polymer. The encapsulation efficiency of different formulation varied from 53 ± 1.2% to 78 ± 1.5%. The mean particle size of the optimized formulation F-14 was 106.4 ± 0.5 μm. Surface morphology revealed that chitosan microspheres were discrete and spherical in shape with a porous surface. The release of MTZ from chitosan microspheres was rapid up to 4 h, and then it was continuously and slowly released up to 48 h. Optimized formulation (F-14) was found to be stable under accelerated storage conditions based on International Conference on Harmonisation guidelines. Pharmacokinetic studies revealed that the optimized formulation showed significant increases in systemic exposure (AUC = 177.70 ± 7.39 μg·h/mL), half-life (4.72 ± 0.46 h) and reduced clearance (0.009 ± 0.0001 L/h) compared to pure drug administration. Hence, the present study demonstrates that controlled release formulation of MTZ microspheres using chitosan can improve pharmacokinetic profiles of MTZ.     

Formulation and in vitro characterization of spray dried microspheres of amoxicillin

The purpose of the present study was to design muco-adhesive chitosan microspheres containing amoxicillin. Chitosan microspheres with a small particle size and good sphericity were prepared by a spray-drying method followed by chemical treatment with a chemical crosslinking agent (glutaraldehyde). Parameters affecting the crosslinking extent of the crosslinking time and the concentration of the crosslinker agent. Crosslinked spray-dried chitosan microspheres were analyzed for their morphological aspects, particle size, drug entrapment efficiency, swelling percent and in vitro drug release. Batch M4 with a drug polymer ratio of 1:2, dissolved in minimum concentration of acetic acid solution treated with glutaraldehyde, was found to be optimal giving controlled drug release for 10 h. It was found that both the increase of glutaraldehyde concentration and crosslinking duration decreased the swelling capacity of chitosan microspheres. This could be directly correlated to drug release from the microspheres.     

Novel interpenetrating network chitosan-poly(ethylene oxide-g-acrylamide) hydrogel microspheres for the controlled release of capecitabine

This paper describes the synthesis of capecitabine-loaded semi-interpenetrating network hydrogel microspheres of chitosan-poly(ethylene oxide-g-acrylamide) by emulsion crosslinking using glutaraldehyde. Poly(ethylene oxide) was grafted with polyacrylamide by free radical polymerization using ceric ammonium nitrate as a redox initiator. Capecitabine, an anticancer drug, was successfully loaded into microspheres by changing experimental variables such as grafting ratio of the graft copolymer, ratio of the graft copolymer to chitosan, amount of crosslinking agent and percentage of drug loading in order to optimize process variables on drug encapsulation efficiency, release rates, size and morphology of the microspheres. A 2(4) full factorial design was employed to evaluate the combined effect of selected independent variables on percentage of drug release at 5h (response). Regression models were used for the response and data were compared statistically using the analysis of variance (ANOVA). Grafting, interpenetrating network formation and chemical stability of the capecitabine after encapsulation into microspheres was confirmed by Fourier infrared spectra (FTIR). Differential scanning calorimetry (DSC) and X-ray diffractometry (XRD) studies were made on drug-loaded microspheres to investigate the crystalline nature of drug after encapsulation. Results indicated amorphous dispersion of capecitabine in the polymer matrix. Scanning electron microscope (SEM) confirmed spherical shapes and smooth surface morphology of the microspheres. Mean particle size of the microspheres as measured by the laser light scattering technique ranged between 82 and 168microm. Capecitabine was successfully encapsulated into semi-IPN microspheres and percentage of encapsulation efficiency varied from 79 to 87. In vitro release studies were performed in simulated gastric fluid (pH 1.2) for the initial 2h, followed by simulated intestinal fluid (pH 7.4) until complete dissolution. The release of capecitabine was continued up to 10h. Release data were fitted to an empirical relationship to estimate the transport parameters. Dynamic swelling studies were performed in the simulated intestinal fluid and diffusion coefficients were calculated by considering the spherical geometry of the matrices.     

Development and in vitro evaluations of gelatin A microspheres of ketorolac tromethamine for intranasal administration

Gelatin A microspheres (MS) of ketorolac tromethamine (KT) for intranasal systemic delivery were developed with the aim to avoid gastro-intestinal complications, to improve patient compliance, to use as an alternative therapy to conventional dosage forms, to achieve controlled blood level profiles, and to obtain improved therapeutic efficacy in the treatment of postoperative pain and migraine. Gelatin A microspheres were prepared using the emulsification-crosslinking technique. The drug was dispersed in polymer gelatin and formulated into a w/o emulsion with liquid paraffin, using glutaraldehyde as a crosslinking agent. The formulation variables were drug loading and the concentrations of polymer (gelatin), co-polymer (chitosan) and the crosslinking agent. All the prepared microspheres were evaluated for physical characteristics, such as particle size, incorporation efficiency, swelling ability, in vitro bioadhesion on rabbit small intestine and in vitro drug release characteristics in pH 6.6 phosphate buffer. All the microspheres showed good bioadhesive properties. Gelatin A and chitosan concentrations, percentage of the crosslinking agent and also the drug loading affected significantly the rate and extent of drug release. The data indicated that the KT release followed Higuchi's matrix model.     

Encapsulation of vitamin C in tripolyphosphate cross-linked chitosan microspheres by spray drying

This paper describes vitamin C-encapsulated chitosan microspheres cross-linked with tripolyphosphate (TPP) using a new process prepared by spray drying intended for oral delivery of vitamin C. Thus, prepared microspheres were evaluated by loading efficiency, particles size analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), zeta potential and in vitro release studies. The microspheres so prepared had a good sphericity and shape but varied with the volume of cross-linking agent solution added. They were positively charged. The mean particle size ranged from 6.1-9.0 microm. The size, shape, encapsulation efficiency, zeta potential and release rate were influenced by the volume of cross-linking agent. With the increasing amount of cross-linking agent, both the particle size and release rate were increased. Encapsulation efficiency decreased from 45.05-58.30% with the increasing amount of TPP solution from 10-30 ml. FTIR spectroscopy study showed that the vitamin C was found to be stable after encapsulation. XRD studies revealed that vitamin C is dispersed at the molecular level in the TPP-chitosan matrix. Well-defined change in the surface morphology was observed with the varying volume of TPP. The sphericity of chitosan microspheres was lost at higher volume of cross-linking agent. The release of vitamin C from these microspheres was sustained and affected by the volume of cross-linking agent added. The release of vitamin C from TPP-chitosan microspheres followed Fick's law of diffusion.     

阿苯达唑-壳聚糖微球的制备及其质量指标的考察

目的:考察阿苯达唑-壳聚糖微球(ABZ-CS-MS)的载药量、包封率、表面形态及结果特性,以及微球在不同介质中的体外释放特性。方法:采用乳化-交联固化法,以液体石蜡为油相,Span-80为乳化剂,戊二醛为交联剂,壳聚糖(chitosan,CS)为载体,制备阿苯达唑-壳聚糖微球(ABZ-CS-MS);应用光学显微镜测量ABZ-CS-MS的的粒径大小及其分布;用扫描电镜(SEM)观察ABZ-CS-MS的表面形态;用红外光谱(fourier transform infraredspectrometer,FT-IR)、X-线粉末衍射法(X-ray power diffraction,X-RD)和差示扫描热量法(differential scanning calo-rimetry,DSC)检测ABZ-CS-MS的特性;用体外动态透析法测定ABZ-CS-MS在不同介质条件下的释药性能。结果:所制备的ABZ-CS-MS形态圆整,粒径分布较为均匀,平均粒径为(153±7)μm,载药量为(20.92±0.15)%,包封率为(25.37±0.22)%;ABZ-CS-MS分别在不同介质(0.1mol/L HCl液、PBS(pH=3.5)、PBS(pH=7.4)和0.9%氯化钠溶液)中的释放均遵循Weibull方程,其中在PBS(pH=3.5)中释放效果最佳。结论:该法制备的ABZ-CS-MS的质量与性能良好,具有较好的载药量,包封率高,形态圆整,缓释作用明显。     

Encapsulation of vitamin C in tripolyphosphate cross-linked chitosan microspheres by spray drying

This paper describes vitamin C-encapsulated chitosan microspheres cross-linked with tripolyphosphate (TPP) using a new process prepared by spray drying intended for oral delivery of vitamin C. Thus, prepared microspheres were evaluated by loading efficiency, particles size analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), zeta potential and in vitro release studies. The microspheres so prepared had a good sphericity and shape but varied with the volume of cross-linking agent solution added. They were positively charged. The mean particle size ranged from 6.1–9.0?µm. The size, shape, encapsulation efficiency, zeta potential and release rate were influenced by the volume of cross-linking agent. With the increasing amount of cross-linking agent, both the particle size and release rate were increased. Encapsulation efficiency decreased from 45.05–58.30% with the increasing amount of TPP solution from 10–30?ml. FTIR spectroscopy study showed that the vitamin C was found to be stable after encapsulation. XRD studies revealed that vitamin C is dispersed at the molecular level in the TPP-chitosan matrix. Well-defined change in the surface morphology was observed with the varying volume of TPP. The sphericity of chitosan microspheres was lost at higher volume of cross-linking agent. The release of vitamin C from these microspheres was sustained and affected by the volume of cross-linking agent added. The release of vitamin C from TPP-chitosan microspheres followed Fick's law of diffusion.     

Crosslinked chitosan microspheres for encapsulation of diclofenac sodium: effect of crosslinking agent

Microspheres of chitosan crosslinked with three different crosslinking agents viz, glutaraldehyde, sulphuric acid and heat treatment have been prepared to encapsulate diclofenac sodium (DS). Chitosan microspheres are produced in a w/o emulsion followed by crosslinking in the water phase by one of the crosslinking methods. Encapsulation of DS has been carried out by soaking the already swollen crosslinked microspheres in a saturated solution of DS. Microspheres are further characterized by FTIR, x-RD and SEM. The in-vitro release studies are performed in 7.4 pH buffer solution. Microspheres produced are spherical and have smooth surfaces, with sizes ranging between 40-230 microm, as evidenced by SEM. The crosslinking of chitosan takes place at the free amino group in all the cases, as evidenced by FTIR. This leads to the formation of imine groups or ionic bonds. Polymer crystallinity increases after crosslinking, as determined by x-RD. The method adopted for drug loading into the microspheres is satisfactory, and up to 28-30% w/w loading is observed for the sulphuric acid-crosslinked microspheres, whereas 23-29 and 15-23% of loadings are obtained for the glutaraldehyde (GA)- and heat-crosslinked microspheres, respectively. Among all the systems studied, the 32% GA crosslinked microspheres have shown the sloxvest release i.e. 41% at 420 min, and a fastest release of 81% at 500 min is shown by heat crosslinking for 3 h. Drug release from the matrices deviates slightly from the Fickian process.     

海藻酸-壳聚糖-聚乳酸羟乙醇酸复合微球的制备及其对蛋白释放的调节

目的制备蛋白的海藻酸-壳聚糖-聚乳酸羟乙醇酸(PLGA)复合微球，以增加蛋白药物的包封率、减少突释和不完全释放。方法以牛血清白蛋白为模型药物采用修饰的乳化、醇洗法制备小粒径海藻酸微囊，再以壳聚糖孵育制得海藻酸-壳聚糖双层微囊，并进一步用PLGA包裹制得复合微球。采用微量BCA试剂盒测定蛋白浓度，考察其包封率及释放行为，改变各种制备因素调节微球的释放特性。结果复合微球粒径约30 μm，形态圆整。与单纯PLGA微球相比，包封率由60%-70%上升至80%以上。复合微球在磷酸盐缓冲液的1 h突释量由40%-50%下降至25%以下，在生理盐水中则进一步下降至5%以下。结论海藻酸-壳聚糖-PLGA复合微球提高了蛋白药物的包封率，减少了药物的突释，并可通过调节PLGA比例调节药物的释放。     

糖类交联明胶微球的制备及其释药特性研究

目的:以生物相容性的糖作交联剂制备明胶药物载体并研究其释药特性。方法:用葡萄糖、葡聚糖、氧化葡萄糖、氧化葡聚糖作交联剂制备明胶盘和微球,测定其溶胀动力学,分别以阿司匹林和牛血清白蛋白为药物模型,紫外分光光度法测定药物包裹率、载药率,并检测明胶微球在模拟体内条件下药物的释放速率。结果:葡萄糖、氧化葡萄糖、葡聚糖、氧化葡聚糖作交联剂制备的凝胶溶胀率分别为204%、246%、166%、233%;4种阿司匹林和牛血清白蛋白明胶微球平均载药率分别为8.73%和4.05%,平均包封率分别为62.55%和31.40%;2h药物释放百分率依次为30%、14%、76%、73%和97.2%、86.6%、60.8%、50.1%。结论:上述4种糖均可以取代化学交联剂制备明胶微球;天然糖交联微球缓释效果优于氧化糖。