依托泊苷鼻用壳聚糖微球的制备及体外释放度考察

目的研制依托泊苷鼻黏膜给药壳聚糖微球,对微球的制备方法及体外释放度进行考察.方法以壳聚糖为栽体,甲醛为交联剂,采用乳化交联固化法制备微球,对微球的粒径、形态及体外释药进行研究.结果微球的外观圆整,平均粒径为(46.9±0.7)μm,78.4 %的微球粒径在30～70μm范围内,体外释药符合Higuchi模型.结论依托泊苷壳聚糖微球制备工艺简单、稳定,包封率高,药物释放符合鼻腔给药要求.     

鞣花酸壳聚糖-海藻酸钠微球的制备工艺

目的:优化鞣花酸壳聚糖-海藻酸钠微球的最佳制备工艺。方法:采用一步法,以壳聚糖-海藻酸钠作为载体材料制备鞣花酸微球,并以微球载药量和包封率为考察指标,通过单因素筛选及正交设计优化出鞣花酸壳聚糖-海藻酸钠微球的制备工艺。用溶出仪在900 ml释放介质(pH 6.86)和120 r·min^-1转速条件下测定释放度。结果:优化工艺为海藻酸钠与药物比为3:1,氯化钙质量分数为2%,海藻酸钠质量分数为2%,壳聚糖质量分数为0.1%,温度为60℃,pH为5,所得鞣花酸平均粒径为(980±100)μm,平均载药量为27.22%,平均包封率为97.73%,48 h释放度为74.22%。结论:本制备工艺稳定,操作简便,重现性好,可用于鞣花酸壳聚糖-海藻酸钠微球的制备。     

尼莫地平壳聚糖缓释微球制备工艺及性能研究

目的研究以壳聚糖和阿拉伯胶为基质,制备尼莫地平缓释微球的工艺。方法以微球的药物包封率为制备工艺优化指标,得出成球的最佳制备工艺条件。结果最佳工艺条件为:搅拌速度400 r/min,pH 4.5,壳聚糖与阿拉伯胶重量浓度比为1∶1,戊二醛用量为1%。结论以最佳制备工艺条件制备载药微球,重现性好,工艺稳定,同时体外释放实验表明,该微球具有较好的缓释作用。     

多柔比星壳聚糖微球的制备及其特性研究

目的 以壳聚糖为载体材料,多柔比星为模型药物, 制备脑内局部给药缓释微球。方法 以液体石蜡为油相,L-抗坏血酸棕榈酸酯为交联剂,司盘-80为乳化剂,采用乳化化学交联技术制备多柔比星脑用微球。用动态透析法检测微球的体外释放特性。结果 多柔比星/壳聚糖的质量比为1：9的载药微球形态良好,粒径分布较为均匀,平均粒径为（9.41±2.43） μm,载药量为（8.49±0.37）%,包封率为（70.56±4.23）%。体外释放具有良好的缓释效果。结论 所优化的制备工艺稳定,适用于多柔比星壳聚糖脑用微球的制备.     

汉防已甲素壳聚糖微球的制备和质量研究

目的 对汉防己甲素壳聚糖微球的制备工艺和制得的微球的质量进行研究.方法 以壳聚糖为载体,采用乳化交联法制备汉防己甲素壳聚糖微球.在单因素考察的基础上,利用正交试验设计优化汉防己甲素壳聚糖微球制备工艺,并对制得微球的粒径,形态,工艺重复性,稳定性,体外突释情况等进行研究.结果 制得的微球的形态圆整,微球的平均粒径为(9.73±1.34)μm,粒径在9～12 μm的占总数的85%以上,载药量为(32.21±3.21)%,包封率为(40.33±5.32)%,最佳工艺条件重复性良好.结论 筛选的最佳处方工艺可制备性质优良的微球.     

替莫唑胺壳聚糖缓释微球的制备及体外释药特性

目的:制备替莫唑胺壳聚糖缓释微球,并对其体外释药模式进行研究.方法:以替莫唑胺为模型药物,采用乳化交联法制备壳聚糖微球,两步优化法优化处方和制备工艺.通过测定微球的粒径及其分布、载药量、包封率和体外释放速度对微球进行质量评价.结果:优化工艺制得的微球平均粒径为(3.9±1.6)μm,载药量为(7.1±0.5)%(n=3),包封率为(25.0±0.8)%(n=3),体外释药特性研究具有良好的缓释特性,在0～8 h符合Higuchi方程,Q=11.717 26.951t1/2(r=0.980),8～24 h符合一级释放曲线,lnQ=4.37 0.007 5t(r=0.983).结论:通过优化处方和制备工艺,采用乳化交联法可制备出以壳聚糖为载体、替莫唑胺为模型药物的缓释微球,其体外释药具有明显的缓释作用.     

格列吡嗪壳聚糖-三聚磷酸钠pH敏感性微球的制备及性能研究

目的:以壳聚糖为载体,制备格列吡嗪壳聚糖-三聚磷酸钠pH敏感性微球,并对其性能进行研究。方法:采用正交试验设计法L9(34)优化处方组成及微球制备工艺,通过扫描电镜法、红外光谱法对微球的表面形态及内部结构进行表征,并对其体外释放性能进行研究。结果:最佳工艺条件下制得的微球形状圆整、表面光滑,平均包封率、载药量、粒径分别为75.17%,11.04%和50μm。此微球在模拟胃液中3 h,累积释放率达50%,转移到肠液中19 h后,累积释放率达80%。结论:该微球具有明显的pH敏感性和控释性能。     

去甲斑蝥素壳聚糖微球的制备及其体外释放特性

目的:制备去甲斑蝥素壳聚糖微球,并考察其体外释放特性.方法:以液体石蜡为油相,Span-80为乳化剂,甲醛作为交联剂,采用乳化-交联法制备去甲斑蝥素壳聚糖微球.均匀设计优化制备工艺,扫描电镜观察微球表面形态,动态透析法检测微球的体外释放特性.结果:制备的微球形态圆整,粒径分布较为均匀,平均粒径(25±10)μm,载药量(15.08±2.85)%,包封率(57.80±1.35)%.微球在0.1 mol·L-1HCl、磷酸盐缓冲液(pH值5.3)和生理氯化钠溶液中的释放均遵循Higuchi方程.结论:所优化的制备工艺简单易行,载药量高,缓释作用显著.     

盐酸川芎嗪羧甲基壳聚糖丝素蛋白微球的制备和体外释放特性

摘要：目的:制备一种包载盐酸川芎嗪的羧甲基壳聚糖丝素蛋白微球,以期延长药物的释放时间。方法:采用乳化-化学交联法制备盐酸川芎嗪羧甲基壳聚糖丝素蛋白微球;采用高效液相色谱法测定盐酸川芎嗪的含量;采用Box-Behnken设计-效应面法优化载药微球的制备工艺;考察盐酸川芎嗪注射液和载药微球的体外释放特性。结果:优化的制备工艺条件为:丝素蛋白质量浓度3.0 mg·ml-1、盐酸川芎嗪质量浓度2.0 mg·ml-1、搅拌速度600 r·min-1;制得的载药微球的粒径为（34.4±2.3）μm、包封率为（67.6±1.3）%（n=4）,与软件模型预测值接近,偏差绝对值均小于5%。盐酸川芎嗪注射液中的药物在60 min内已完全释放;而载药微球在30 min内药物快速释放,60 min后药物释放速率较缓慢,180 min时完全释放。载药微球在6种释放介质中的体外释放过程均符合Higuchi方程,体现出良好的缓释特性。结论:优化后的盐酸川芎嗪羧甲基壳聚糖丝素蛋白微球制备工艺简便易行,微球形态圆整,包封率载药量较高,体外释放具有缓释特性。     

盐酸多西环素羧甲基壳聚糖微球的体外释放研究

目的:探讨各因素对盐酸多西环素羧甲基壳聚糖微球体外释放度的影响。方法:采用乳化-交联固化法制备盐酸多西环素羧甲基壳聚糖微球(doxycycline hydrochloride-carboxymethyl chitosan-microspheres,DXY-CMCTS-MS),采用动态透析法测定体外释药性能,用紫外分光法测定盐酸多西环素浓度,绘制其释放曲线。结果:释放介质pH越大,交联剂量越大,固化时间越长,药物/载体比例越小,药物的释放则越慢。结论:该制剂制备工艺切实可行,所得DXY-CMCTS-MS具有明显的缓释效果。     

5-fluorouracil loaded chitosan microspheres for chemoembolization

In this study, chitosan microspheres were prepared by a suspension cross-linking technique. A petroleum ether/mineral oil mixture was used as the suspension medium which includes an emulsifier, e.g. Tween-80. Glutaraldehyde was used as the cross-linker. 5-Fluorouracil was incorporated in the matrix for the possible use of the microspheres in chemoembolization. The size and size distribution of the chitosan microspheres varied in the size range of 100-200 microns, by changing the emulsifier concentration, stirring rate, chitosan/solvent ratio and drug/chitosan solution ratio. In summary, the size and size distribution of the microspheres decreased when the emulsifier concentration and stirring rate were increased. Smaller microspheres with narrower size distributions were obtained when the chitosan/solvent ratio and drug/chitosan ratio were lower. It was possible to load the chitosan microspheres with 5-FU to a concentration of 10.4 mg 5-FU/g chitosan. Around 60% of the loaded drug was released within the first 24 h, then the release rate became much slower.     

5-Fluorouracil loaded chitosan microspheres for chemoembolization

In this study, chitosan microspheres were prepared by a suspension crosslinking technique. A petroleum ether/mineral oil mixture was used as the suspension medium which includes an emulsifier, e.g. Tween-80. Glutaraldehyde was used as the cross-linker. 5-Fluorouracil was incorporated in the matrix for the possible use of the microspheres in chemoembolization. The size andsize distributionof thechitosanmicrospheres variedinthesizerangeof 100-200mum, by changing the emulsifier concentration, stirring rate, chitosan/ solvent ratio and drug/chitosan solution ratio. In summary, the size and size distribution of the microspheres decreased when the emulsifier concentration and stirring rate were increased. Smaller microspheres with narrower size distributions were obtained when the chitosan/solvent ratio and drug/chitosan ratiowerelower. Itwas possibletoload thechitosanmicrospheres with 5-FU to a concentration of 10.4mg 5-FU/g chitosan. Around 60%of the loaded drug was released within the first 24h, then the release rate became much slower.     

Chitosan and chondroitin microspheres for oral-administration controlled release of metoclopramide.

This study investigated the usefulness of chitosan and chondroitin sulphate microspheres for controlled release of metoclopramide hydrochloride in oral administration. Microspheres were prepared by spray drying of aqueous polymer dispersions containing the drug and different amounts of formaldehyde as cross-linker. Drug release kinetics were investigated in vitro in media of different pH. Chondroitin sulphate microspheres scarcely retarded drug release, regardless of cross-linker concentration and medium pH, and were thus not further characterized. Chitosan microspheres prepared with more than 15% formaldehyde (w/w with respect to polymer) showed good control release (more than 8 h), and release rates were little affected by medium pH. Release from chitosan microspheres prepared with 20% formaldehyde was independent of pH, suggesting that this may be the most appropriate formulation. The size distribution of the chitosan microparticles was clearly bimodal, with the smaller-diameter subpopulation corresponding to microsphere fragments and other particles. Electron microscopy showed the chitosan microspheres to be almost-spherical, though with shallow invaginations. The kinetics of drug release from chitosan microspheres were best fitted by models originally developed for systems in which release rate is largely governed by rate of diffusion through the matrix.     

Synthesis and characterization of cross-linked chitosan microspheres for drug delivery applications

The present study deals with the synthesis and characterization of cross-linked chitosan microspheres containing an hydrophilic drug, hydroquinone. The microspheres were prepared by the suspension cross-linking method using glutaraldehyde as the cross-linking agent of the polymer matrix. Perfectly spherical cross-linked hydrogel microspheres loaded with hydroquinone were obtained in the size range of 20–100 μm. The effect of the degree of polymer cross-linking, chitosan molecular weight, chitosan concentration and amount of the encapsulated drug on the hydroquinone release kinetics was extensively investigated. It was found that slower drug release rates were obtained from microspheres prepared by using a higher initial concentration of chitosan, a higher molecular weight of chitosan or/and a lower drug concentration. Most importantly, it was shown that the release rate of hydroquinone was mainly controlled by the polymer cross-linking density and, thus, by the degree of swelling of the hydrogel matrix.     

Synthesis and characterization of cross-linked chitosan microspheres for drug delivery applications

The present study deals with the synthesis and characterization of cross-linked chitosan microspheres containing an hydrophilic drug, hydroquinone. The microspheres were prepared by the suspension cross-linking method using glutaraldehyde as the cross-linking agent of the polymer matrix. Perfectly spherical cross-linked hydrogel microspheres loaded with hydroquinone were obtained in the size range of 20-100 microm. The effect of the degree of polymer cross-linking, chitosan molecular weight, chitosan concentration and amount of the encapsulated drug on the hydroquinone release kinetics was extensively investigated. It was found that slower drug release rates were obtained from microspheres prepared by using a higher initial concentration of chitosan, a higher molecular weight of chitosan or/and a lower drug concentration. Most importantly, it was shown that the release rate of hydroquinone was mainly controlled by the polymer cross-linking density and, thus, by the degree of swelling of the hydrogel matrix.     

Chitosan-coated alginate microspheres for embolization and/or chemoembolization: in vivo studies

In this study, chitosan-coated alginate microspheres were prepared by the ionic complexation of alginate and chitosan biopolymers to use in embolization and/or chemoembolization studies. Biopolymeric microspheres were prepared by the ionic gelation technique of alginate with a suitable divalent cation (i.e. CaCl2) in a suspension medium composed of mineral oil and petroleum ether including emulsifier (i.e. Tween-80) and then obtained microspheres were coated with chitosan in an aqueous chitosan solution while the medium was magnetically stirred. The obtained microspheres are in the size range of 100-400 microm and they can be prepared as required by changing the preparation conditions (i.e. stirring rate, concentration of biopolymers, molecular weight and concentration of chitosan, etc.). In the in vivo studies, New Zealand rabbits were used as the test animals. Both complete and partial embolization of the kidney were achieved by using the microspheres. The renal angiograms obtained before/after embolization and the histopathological observations showed the feasibility of the chitosan-coated alginate microspheres as an alternative embolization and/or chemoembolization agent.     

Preparation and characterization of Mitomycin-C loaded chitosan-coated alginate microspheres for chemoembolization

Mitomycin-C loaded and chitosan-coated alginate microspheres were prepared for use in chemoembolization studies. In this respect, first alginate microspheres were prepared by using a spraying method using an extrusion device with a small orifice and following suspension cross-linking in an oil phase. Chitosan-coating onto the alginate microspheres was achieved by polyionic complex formation between alginate and chitosan. CaCl(2) was used as a cross-linker for alginate microspheres. The obtained chitosan-coated alginate microspheres were spherical shaped and approximately 100-400 microm average size. The microspheres were evaluated based on their swellability and the swelling ratio was changed between 50-280%. CaCl(2) concentration, stirring rate, chitosan molecular weight, chitosan concentration and time for coating with chitosan were selected as the effective parameters on microsphere size and swelling ratio. Equilibrium swellings were achieved in approximately 30 min. On the other hand, chitosan molecular weight, chitosan concentration and time for coating with chitosan were found as the most effective parameters on both drug loading ratio and release studies. Maximum drug loading ratio of 65% was achieved with high molecular weight (HMW) chitosan, highest chitosan concentration (i.e. 1.0% v/v) and shortest time for coating with chitosan (i.e. 1 h) values.     

Chitosan-coated alginate microspheres for embolization and/or chemoembolization: In vivo studies

In this study, chitosan-coated alginate microspheres were prepared by the ionic complexation of alginate and chitosan biopolymers to use in embolization and/or chemoembolization studies. Biopolymeric microspheres were prepared by the ionic gelation technique of alginate with a suitable divalent cation (i.e. CaCl₂) in a suspension medium composed of mineral oil and petroleum ether including emulsifier (i.e. Tween-80) and then obtained microspheres were coated with chitosan in an aqueous chitosan solution while the medium was magnetically stirred. The obtained microspheres are in the size range of 100–400?µm and they can be prepared as required by changing the preparation conditions (i.e. stirring rate, concentration of biopolymers, molecular weight and concentration of chitosan, etc.). In the in vivo studies, New Zealand rabbits were used as the test animals. Both complete and partial embolization of the kidney were achieved by using the microspheres. The renal angiograms obtained before/after embolization and the histopathological observations showed the feasibility of the chitosan-coated alginate microspheres as an alternative embolization and/or chemoembolization agent.     

Microencapsulation of lipophilic drugs in chitosan-coated alginate microspheres.

Chitosan-coated alginate microspheres containing a lipophilic marker dissolved in an edible oil, were prepared by emulsification/internal gelation and the potential use as an oral controlled release system investigated. Microsphere formation involved dispersing a lipophilic marker dissolved in soybean oil into an alginate solution containing insoluble calcium carbonate microcrystals. The dispersion was then emulsified in silicone oil to form an O/W/O multiple phase emulsion. Addition of an oil soluble acid released calcium from carbonate complex for gelation of the alginate. Chitosan was then applied as a membrane coat to increase the mechanical strength and stabilize the microspheres in simulated intestinal media. Parameters studied included encapsulation yield, alginate concentration, chitosan molecular weight and membrane formation time. Mean diameters ranging from 500 to 800 micron and encapsulation yields ranging from 60 to 80% were obtained. Minimal marker release was observed under simulated gastric conditions, and rapid release was triggered by transfer into simulated intestinal fluid. Higher overall levels of release were obtained with uncoated microspheres, possibly due to binding of marker to the chitosan membrane coat. However the slower rate of release from coated microspheres was felt better suited as a delivery vehicle for oil soluble drugs.     

Preparation and characterization of Mitomycin-C loaded chitosan-coated alginate microspheres for chemoembolization

Mitomycin-C loaded and chitosan-coated alginate microspheres were prepared for use in chemoembolization studies. In this respect, first alginate microspheres were prepared by using a spraying method using an extrusion device with a small orifice and following suspension cross-linking in an oil phase. Chitosan-coating onto the alginate microspheres was achieved by polyionic complex formation between alginate and chitosan. CaCl₂ was used as a cross-linker for alginate microspheres. The obtained chitosan-coated alginate microspheres were spherical shaped and ～100–400?µm average size. The microspheres were evaluated based on their swellability and the swelling ratio was changed between 50–280%. CaCl₂ concentration, stirring rate, chitosan molecular weight, chitosan concentration and time for coating with chitosan were selected as the effective parameters on microsphere size and swelling ratio. Equilibrium swellings were achieved in ～30?min. On the other hand, chitosan molecular weight, chitosan concentration and time for coating with chitosan were found as the most effective parameters on both drug loading ratio and release studies. Maximum drug loading ratio of 65% was achieved with high molecular weight (HMW) chitosan, highest chitosan concentration (i.e. 1.0% v/v) and shortest time for coating with chitosan (i.e. 1?h) values.