紫杉醇壳聚糖肺靶向微球的制备

目的研制具有肺靶向性的紫杉醇壳聚糖微球,并对处方工艺进行优化。方法以壳聚糖为载体,采用乳化一化学交联法制备紫杉醇壳聚糖微球。单因素试验考察了油／水体积比、紫杉醇浓度、乳化时间、乳化剂量等因素,采用正交设计优化微球制备工艺,以HPLC法测定微球载药量、包封率。结果制得的微球显微观察形态圆整、表面光滑,无黏连;平均粒径为（8．23±0．25）μm,粒径在7～12μm平均占微球总数的84．2％,载药量为16．20％±1．15％,包封率为81．29％±1．62％。结论筛选的最佳处方工艺制备的微球粒径大小适宜,可满足肺靶向微球的要求并免除过敏试剂的加入。     

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.     

金钱草壳聚糖微球制备工艺研究

目的：对金钱草壳聚糖微球的制备工艺和包封率、粒径等特性进行初步研究。方法：以生物降解材料壳聚糖为载体,采用乳化一交联法制备金钱草壳聚糖微球,并采用正交试验优化制备工艺。结果：所制备的金钱草壳聚糖微球外观圆整,平均粒径为48．34μm,载药量为15．11％,包封率为59．55％。结论：所制备的金钱草壳聚糖微球重现性良好,载药量较高,制备工艺可行。     

星点设计法优化汉防己甲素壳聚糖微球的处方

目的:星点设计法优化汉防己甲素壳聚糖微球的处方,提高该制剂的肺靶向性。方法:采用乳化交联法制备壳聚糖微球,自变量为汉防己甲素和壳聚糖的重量比、水相和油相的体积比、壳聚糖浓度,以微球收率、载药量、包封率、平均粒径和跨距为因变量对各自变量的各水平进行多元线性回归和二项式拟合,选择较佳工艺条件并对优化区间进行预测分析。结果:收率、载药量、包封率、平均粒径和跨距用二项式模型拟合较好,最佳优化制备处方的汉防己甲素和壳聚糖的重量百分比为61·97%,水相和油相的体积比为13·51%,壳聚糖浓度为2·37%。结论:星点设计可用于优化制剂处方,所制汉防己甲素壳聚糖微球粒径大小适宜,可满足肺靶向的要求。     

奥沙普秦壳聚糖-海藻酸钠缓释微球的制备

目的：目的：选择奥沙普秦作为模型药制备壳聚糖-海藻酸钠缓释微球。方法：采用滴制法制备奥沙普秦壳聚糖-海藻酸钠缓释微球，通过正交试验设计优化了处方和工艺，考察其理化特征及体外释药行为。结果：优化处方制得的微球包封率及载药量分别为98．36％和16．26％，平均粒径为（346．6±164．1）μm；1h药物释放达到36％，随后药物的释药行为是一个缓释过程。结论：制得了载药量较大，包封率较高的奥沙普秦壳聚糖-海藻酸钠缓释微球。     

牛血清白蛋白阳离子微球的制备及体外评价

目的制备牛血清白蛋白（BSA）口服阳离子微球,考察天然阳离子物质壳聚糖（CHS）的加入对蛋白微球的粒径、电动电势、包封率、载药量及体外释放情况的影响。方法以乳酸／羟基乙酸共聚物（PLGA）和壳聚糖（CHS）为载体材料,采用W／O／W复乳-溶剂挥发法制备牛血清白蛋白乳酸／羟基乙酸共聚物-壳聚糖（PLGA／CHS）阳离子微球。通过正交设计优化制备工艺,确定最佳处方。建立准确而简便的蛋白含量测定方法,并对微球进行体外评价。结果最佳处方为：BSA浓度为150g·L^-1、PLGA浓度为8％、外水相体积为80mL、壳聚糖浓度为0．2％。制得的微球形态圆整,平均粒径为（6．9±5．5）μm,为表面荷正电的阳离子微球[ζ电势=00．0±0．6）mV],包封率为（75．4±4．6）％,载药量为（9．3±0．2）％。体外释放结果表明,在模拟胃液和模拟肠液中,壳聚糖的加入均能减少突释,延缓药物的释放。结论与PLGA微球相比,制得的PLGA／CHS阳离子微球表面带正电,具有较高的包封率和载药量,可以延缓药物释放,同时减少突释现象。     

载环孢素A海藻酸钙-壳聚糖微球的制备及体外释放特性

目的:针对角膜移植术后免疫抑制治疗需求,制备眼部局部给药的小粒径载环孢素A缓释微球,并进行体外释放考察。方法:以海藻酸钠、壳聚糖为载体材料,采用静电液滴工艺,通过向制备体系添加表面活性剂,制备小粒径载环孢素A微球,设计正交试验优化处方工艺,扫描电镜观察微球表面形态,动态透析法考察微球的体外释放特性。结果:所制微球形态良好,粒径分布窄,平均粒径为(12.4±0.8)μm,包封率为(82.8±1.8)%,载药量为(50.1±1.2)%,体外释放行为用Higuchi方程拟合效果最好。结论:采用静电液滴工艺,通过减小制备体系的表面张力,制备了球形度优良、粒径小、包封率和载药量较高的载环孢素A的壳聚糖-海藻酸盐缓释微球,所得制剂的体外释药规律服从扩散机制。     

多西紫杉醇白蛋白纳米粒的制备及体外评价

目的：制备多西紫杉醇白蛋白纳米粒，考察白蛋白和多西紫杉醇的处方量及乙醇加入量等因素对其形态、粒径、Zeta电位、收率、包封率、载药量和体外释药特性的影响，并对处方工艺进行优化。方法：采用去溶剂化-化学交联法制备多西紫杉醇白蛋白纳米粒，透射电镜观察纳米粒形态，马尔文激光粒度仪测定其粒径分布及Zeta电位，考马斯亮兰-酶标仪法测定纳米粒收率，HPLC法测定纳米粒包封率和载药量；以累积释药百分率为指标，通过方程拟合释药曲线，考察制剂的体外释药特性。处方优化采用星点设计-效应面优化法，应用SAS统计软件对数据进行处理。结果：优化处方制得的纳米粒为类球形，平均粒径65．3nm，Zeta电位-31．4mV，纳米粒收率95．0％，包封率74．3％，载药量4．65％，制剂24小时体外累积释药百分率为74．4％。结论：难溶性抗癌药物多西紫杉醇可以采用去溶剂化-化学交联法制备成白蛋白纳米粒，其粒径小，稳定性高，可显著提高多西紫杉醇在水相中的浓度。其优化处方中药物的释放显著慢于原料药磷酸盐缓冲溶液的释放，具有缓释效果。     

紫杉醇肺靶向微球的制备及体内外评价

目的用生物可降解材料聚乳酸-聚羟基乙酸共聚物(PLGA)制备肺靶向紫杉醇缓释微球。方法在单因素考察的基础上进行正交试验设计,筛选出肺靶向紫杉醇PLGA微球的最佳制备工艺条件;利用桨板法研究了微球的体外释药规律;用小鼠为实验对象,研究了紫杉醇聚乳酸微球的体内组织药物分布。结果制得的微球形态圆整,粒径在5~15μm范围内的占总体积的87.18%,微球平均粒径为9.65μm;包封率为83.8%;载药量为19.7%;体外释药符合Higuchi方程Q=-2.193 7 22.009t0.5,r=0.990 4;体内实验表明紫杉醇微球混悬剂较普通注射剂更趋于聚集在肺组织。结论微球制备工艺稳定,具有明显的缓释作用和肺靶向性。     

盐酸度洛西汀壳聚糖微球的制备与表征

目的制备盐酸度洛西汀壳聚糖微球,并对处方工艺进行筛选。方法采用正交实验设计,以壳聚糖为分散介质,乳化交联法制备盐酸度洛西汀壳聚糖微球。结果平均粒径为16.25μm,载药量为31.22%,药物包封率为75.48%。结论该方法制得的微球外观均匀圆整,分散性良好,粒径分布均匀     

Enhancing drug incorporation into tetracycline-loaded chitosan microspheres for periodontal therapy

PURPOSE: To identify optimal formulation parameters for enhancing the incorporation of tetracycline hydrochloride into chitosan microspheres for periodontal therapy. METHODS: Tetracycline-loaded chitosan microspheres were prepared by ionotropic gelation. Various formulation parameters (salt form of drug, aqueous phase pH, anion structure, inorganic salts and electrolytes, preparation method) were investigated for their influence on drug incorporation efficiency. Microspheres were assessed in terms of drug entrapment and content, microsphere recovery, particle size and morphology. RESULTS: Although drug incorporation efficiency was increased marginally, the use of a dihydrate form of the drug was not considered feasible due to the lowered microsphere recovery and higher costs. A decrease in the aqueous pH from 9 to 6 enhanced drug incorporation efficiency without an adverse effect on microsphere morphology. The use of inorganic salts/electrolytes and other approaches of microsphere preparation did not significantly enhance drug incorporation efficiency and these approaches also adversely affected microsphere morphology. The ionotropic preparation method in terms of the drug loading technique significantly affected drug incorporation efficiencies. CONCLUSIONS: This study has shown that formulation variables can be exploited in order to enhance the incorporation of a water soluble drug into chitosan microspheres using the ionotropic gelation technique. Based on a comparison of all results obtained with the different approaches, the modification of the aqueous phase to pH 6 was identified as the most feasible approach.     

应用人工神经网络—遗传算法优化多西紫杉醇微球制备工艺参数

目的优化多西紫杉醇壳聚糖微球的制备工艺参数。方法应用人工神经网络对微球制备工艺参数与考察指标之间的关系进行模型拟合,并结合遗传算法优化微球的制备工艺参数。结果模型参数优化结果为:壳聚糖浓度3.730 8%、乳化剂用量0.500 4 g、油水体积比1.843 3、药载比25.027 7、交联剂用量2.246 5 mL、搅拌乳化时间63.419 1 min、搅拌速率611.922 8 r.min1。考察指标预测结果是:微球的载药量43.653 8%、粒径8.168 5μm、跨距0.594 0。验证实验数据与网络模型优化结果基本吻合。结论应用人工神经网络建模结合遗传法寻优,可以实现多西紫杉醇壳聚糖微球制备工艺参数的优化。     

Enhancing drug incorporation into tetracycline-loaded chitosan microspheres for periodontal therapy

Purpose: To identify optimal formulation parameters for enhancing the incorporation of tetracycline hydrochloride into chitosan microspheres for periodontal therapy.

Methods: Tetracycline-loaded chitosan microspheres were prepared by ionotropic gelation. Various formulation parameters (salt form of drug, aqueous phase pH, anion structure, inorganic salts and electrolytes, preparation method) were investigated for their influence on drug incorporation efficiency. Microspheres were assessed in terms of drug entrapment and content, microsphere recovery, particle size and morphology.

Results: Although drug incorporation efficiency was increased marginally, the use of a dihydrate form of the drug was not considered feasible due to the lowered microsphere recovery and higher costs. A decrease in the aqueous pH from 9 to 6 enhanced drug incorporation efficiency without an adverse effect on microsphere morphology. The use of inorganic salts/electrolytes and other approaches of microsphere preparation did not significantly enhance drug incorporation efficiency and these approaches also adversely affected microsphere morphology. The ionotropic preparation method in terms of the drug loading technique significantly affected drug incorporation efficiencies.

Conclusions: This study has shown that formulation variables can be exploited in order to enhance the incorporation of a water soluble drug into chitosan microspheres using the ionotropic gelation technique. Based on a comparison of all results obtained with the different approaches, the modification of the aqueous phase to pH 6 was identified as the most feasible approach.     

Optimization of Chitosan Succinate and Chitosan Phthalate Microspheres for Oral Delivery of Insulin using Response Surface Methodology

In the present study, a Box-Behnken experimental design was employed to statistically optimize the formulation parameters of chitosan phthalate and chitosan succinate microspheres preparation. These microspheres can be useful for oral insulin delivery system. The effects of three parameters namely polymer concentration, stirring speed and cross linking agent were studied. The fitted mathematical model allowed us to plot response surfaces curves and to determine optimal preparation conditions. Results clearly indicated that the crosslinking agent was the main factor influencing the insulin loading and releasing. The in vitro results indicated that chitosan succinate microspheres need high amount of crosslinking agent to control initial burst release compared to chitosan phthalate microspheres. The reason may be attributed that chitosan succinate is more hydrophilic than chitosan phthalate. The relative pharmacological efficacy for chitosan phthalate and chitosan succinate microspheres (18.66 ± 3.84%, 16.24 ± 4%) was almost three-fold higher than the efficacy of the oral insulin administration (4.68 ± 1.52%). These findings suggest that these microspheres are promising carrier for oral insulin delivery system.     

Optimization of chitosan succinate and chitosan phthalate microspheres for oral delivery of insulin using response surface methodology

In the present study, a Box-Behnken experimental design was employed to statistically optimize the formulation parameters of chitosan phthalate and chitosan succinate microspheres preparation. These microspheres can be useful for oral insulin delivery system. The effects of three parameters namely polymer concentration, stirring speed and cross linking agent were studied. The fitted mathematical model allowed us to plot response surfaces curves and to determine optimal preparation conditions. Results clearly indicated that the crosslinking agent was the main factor influencing the insulin loading and releasing. The in vitro results indicated that chitosan succinate microspheres need high amount of crosslinking agent to control initial burst release compared to chitosan phthalate microspheres. The reason may be attributed that chitosan succinate is more hydrophilic than chitosan phthalate. The relative pharmacological efficacy for chitosan phthalate and chitosan succinate microspheres (18.66 +/- 3.84%, 16.24 +/- 4%) was almost three-fold higher than the efficacy of the oral insulin administration (4.68 +/- 1.52%). These findings suggest that these microspheres are promising carrier for oral insulin delivery system.     

Preparation, characterization and pharmacokinetics of N-palmitoyl chitosan anchored docetaxel liposomes

The objective of this work was to investigate the preparation, characterization and pharmacokinetics of N-palmitoyl chitosan anchored docetaxel liposomes. To decrease toxic effects and improve antitumour efficacy of the drug, docetaxel has been incorporated in liposomes; the formulation, stability and pharmacokinetics of plain docetaxel liposomes (PDLs), PEGylated docetaxel liposomes (PEGDLs) and N-palmitoyl chitosan anchored docetaxel liposomes (NDLs) were compared. NDL was more stable than PDL and PEGDL in-vitro, especially in the presence of serum at 37 degrees C. The concentration of docetaxel in the plasma of rats after intravenous administration of docetaxel injection, PDL, PEGDL and NDL was studied by RP-HPLC. The pharmacokinetic behaviour of docetaxel injection, PDL, PEGDL and NDL were significantly different. These findings suggest that anchored liposomes could increase the stability of docetaxel in-vivo, as compared with plain liposomes, but the improvement was not more significant than PEGylated liposomes. N-Palmitoyl chitosan as a new polymeric membrane to anchor liposome was useful to stabilize liposomes containing anti-tumour drug.     

Nasal delivery of insulin using chitosan microspheres

Nasal delivery of insulin is an alternative route for administration of this drug. The objective of this study was preparation of chitosan microspheres for insulin nasal delivery. After preparation of insulin chitosan microspheres by emulsification-cross linking process, the effect of chitosan quantity (200-400mg), cross-linker type (ascorbic acid or ascorbyl palmitate) and amount (70-140 mg) were studied on the morphology, particle size, loading efficiency, flow and release of insulin from the microspheres by a factorial design. Optimized formulation was administered nasally in four groups of diabetic rats and their serum insulin levels were analysed by the insulin enzyme immunoassay kit and the serum glucose by the glucose oxidase kits. Insulin loading in microspheres was between 4.7-6.4% w/w, preparation efficiency more than 65% and mean particle size was 20-45 microm. In most cases, drug released followed a Higuchi model. Ascorbic acid caused an increase in stability, particle size and T50%, while decreased the loading efficiency and production efficiency. Increasing the chitosan content, increased particle size, flow and insulin release rate form the microspheres. The increase of cross-linking percentage decreased the flow and size of the microspheres while increase of cross-linking percentage promoted the stability and decreased DE8% of insulin. Microspheres containing 400mg of chitosan and 70mg ascorbyl palmitate caused a 67% reduction of blood glucose compared to i.v. route and absolute bioavaliability of insulin was 44%. The results showed that chitosan microspheres of insulin are absorbable from nasal route.     

Fucosphere--new microsphere carriers for peptide and protein delivery: preparation and in vitro characterization

PURPOSE: Fucoidan is a complex polysaccharide containing sugars and high amounts of sulphate derived from marine brown algaes. In this study, a new microsphere-delivery system based on cross-linking of fucoidan with chitosan, named Fucosphere, was evaluated as a drug carrier. Bovine serum albumin (BSA) was used as a model protein. The effect of fucoidan (1.5, 1.75, 2.0 and 2.5%), chitosan (0.25, 0.50 and 0.75%) and protein (0.25, 0.50 and 0.75%) concentrations, the origin of chitosan and the preparation methods of the particles on the microsphere characteristics were evaluated. METHODS: The microspheres were prepared by a simple method based on the cross-linking of the opposite charged biopolymers. The shape and surface morphologies of the particles were evaluated by scanning electron microscopy (SEM) and the size, charge and encapsulation capacity of the microspheres were determined. The released amount of BSA from the microspheres into phosphate buffered saline (PBS pH 7.4) was determined spectrophotometrically by the Bradford method. SDS-PAGE was performed to check the structural integrity of BSA after the preparation. RESULTS: Smooth and spherical microspheres between the size ranges of 0.61-1.28 microm were obtained. BSA was efficiently encapsulated into the microspheres (51.8-89.5%). All formulation parameters affected the encapsulation capacity of Fucosphere (p < 0.05). The highest encapsulation was obtained with microspheres containing 2.5% of fucoidan (89.5%). CONCLUSIONS: The extent of drug release from the microspheres was dependent on the concentrations of polymers and BSA, chitosan origin and type of preparation method. When the addition methods of protein compared, BSA encapsulated into Fucosphere released slower than the adsorbed protein (E) (p < 0.05). The electrophoretic mobility values of Fucospheres changed between +6.9 and +32.3 mV. In general, BSA release from Fucosphere showed a three-phasic release curve. In conclusion, this new fucoidan microsphere system may be a potential delivery of macromolecular drug such as peptide and protein.     

Plasmid-DNA loaded chitosan microspheres for in vitro IL-2 expression.

Interleukin-2 (IL-2) expression plasmid (pCXWN-hIL-2) loaded chitosan microspheres were evaluated for using in gene-based immunotherapy. Chitosan microspheres containing pCXWN-hIL-2 were prepared by using a precipitation technique. In addition, the effects of different factors such as the concentration (0.35-0.70%) and the molecular weight of chitosan (low and medium molecular weights), the plasmid amount (5-10 microg/ml) and the presence of glutaraldehyde during the encapsulation process, on microsphere characteristics were investigated. The size of microspheres changed between 1.45 and 2.00 microm. All the formulation factors affected the size of microspheres. The structure of plasmid remained unchanged during the encapsulation process and the release studies. Plasmid encapsulation efficiency of chitosan microspheres was high (82-92%). The zeta potential values of microspheres was approximately +5.2 to +12.4 mV. In vitro release properties of microspheres changed with formulation variables. In vitro release of DNA changed with the concentration and molecular weight of chitosan and initial plasmid amount. Addition of glutaraldehyde is not necessary for a formulation. MAT-LyLu, the rat prostate adenocarcinoma cell line, was used for the determination of the in vitro transfectional activity of IL-2 encoding plasmid DNA loaded chitosan microspheres and the level of IL-2 expressed into the cells was assayed using a ELISA kit. High level of IL-2 expression was obtained with plasmid-loaded chitosan microspheres. Microspheres showed similar IL-2 production as lipofectin. The molecular weight of chitosan used and the amount of plasmid influenced the in vitro IL-2 production in the cells. Encapsulation of IL-2 encoding gene into chitosan microspheres might be a useful strategy to increase the expression and to control the delivery of cytokine gene to cells.