异烟肼缓释固体分散体的制备及其体外评价

目的制备异烟肼缓释固体分散体,考察其分散状态和体外溶出速率。方法以水不溶性聚合物乙基纤维素为载体,用溶剂法制备异烟肼缓释固体分散体。采用X射线衍射法、差示扫描量热法和红外光谱法鉴别药物在固体分散体中的存在状态,并对其体外释放情况进行研究。结果 X射线衍射法表明异烟肼在固体分散体中有一部分是以分子状态分散,而另一部分可能以微晶体状态分散;差示扫描量热法表明所制备的缓释固体分散体中不存在药物结晶;红外光谱法结果表明异烟肼与乙基纤维素未发生化学反应;溶出度试验结果表明其具有良好的缓释效果。结论采用溶剂法制备的异烟肼缓释固体分散体可以使药物达到高度分散状态,制备的异烟肼缓释固体分散体具有较好的缓释效果。     

乙基纤维素固体分散体中5F释放度影响因素研究

目的制备不同乙基纤维素与5F固体分散体,并研究不同因素对5F溶出度的影响。方法溶剂法制备乙基纤维素固体分散体颗粒,测定其溶出度,考察各主要因素对5F释放的影响。结果乙基纤维素的黏度、含量、固体分散体的粒度、溶出介质的pH对药物释放均有影响。结论乙基纤维素可用来制备5F缓释固体分散体。     

灯盏花素缓释固体分散体的制备及溶出度的研究

目的 制备灯盏花素缓释固体分散体.方法 以水不溶性聚合物乙基纤维素(EC)为载体,用固体分散技术(溶剂法)制备难溶性药物灯盏花素缓释固体分散体,并进行差热分析和体外释放度研究.结果 药物体外释药行为均符合Higuchi方程;缓释效果与EC用量和固体分散体的粒径有主要关系,药物释放速率随EC用量和黏度的增加而减小;固体分散体粒径越小,药物体外释放速率越快.结论 采用EC作载体,对灯盏花素可起到很好的缓释效果.     

基于固体分散技术的山楂叶总黄酮缓释胶囊的研制及释药机制研究

目的 研制山楂叶总黄酮缓释胶囊,并考察其释药机制。方法 采用喷雾干燥法制备山楂叶总黄酮缓释固体分散体,以乙基纤维素等为载体,以2,6,12 h的释放度为指标,筛选最佳缓释固体分散体处方;采用X-射线衍射、扫描电镜和红外光谱法考察固体分散体中药物分散状态;拟合川北方程,以粉体流动性参数为指标,筛选缓释胶囊的处方辅料,制备山楂叶总黄酮缓释固体分散体胶囊,考察缓释胶囊释药机制,拟合释放动力学方程。结果 山楂叶总黄酮缓释固体分散体最佳处方组成为山楂叶总黄酮：乙基纤维素：卡波姆940P=4：1：0.5;X-射线衍射和扫描电镜结果表明,药物以无定形或分子形式分散于固体分散体中;红外光谱法结果表明,乙基纤维素峰强度增强;缓释胶囊最佳处方组成为固体分散体：微粉硅胶=1：0.3%,所制备缓释胶囊释放度2,6,12 h分别为27.56%,69.50%和96.78%。结论 该缓释胶囊在12 h内呈现良好缓释特征,释放行为符合一级动力学方程,释放机制为扩散和溶蚀相结合机制,且为降解控释型。     

正交试验优选氯化血红素缓释固体分散体处方

目的：探讨氯化血红素缓释固体分散体处方组成。方法：以乙基纤维素为载体，聚乙二醇为致孔剂，采用溶剂法制备氯化血红素缓释固体分散体，用体外释放度为考察指标，运用正交试验对氯化血红素缓释固体分散体最佳处方组成优选。结果：按优选出的最佳处方组成，制备氯化血红素缓释固体分散体，2h的累积体外释放度为30．3％．符合药典规定，6h的累积体外释放度为62．5％，12h的累积体外释放度大于州）％，优化后处方药物释药过程符合Higuchi方程。结论：本处方组成制成固体分散体后，氯化血红素的缓释效果显著，提示本处方可行。     

氟比洛芬乙基纤维素水分散体包衣小丸的制备及体外释药特性

目的：制备氟比洛芬包衣小丸，评价其体外释药特性。方法：离心造粒法制备空白丸芯及载药小丸；以乙基纤维素水分散体为包衣材料，羟阿基甲基纤维素为致孔剂，流化床制备氟比洛芬包衣小丸；释放度实验考察小丸的体外释药特性。结果：包衣小丸缓释胶囊的释放曲线与进口缓释胶囊ForbensR相似，羟丙基甲基纤维素的用量和介质pH值对释药影响显著，而热处理时间和胶囊壳对释药无显著性影响。结论：氟比洛芬包衣小丸具有较理想的体外缓释效果。     

曲美他嗪固体分散体的制备及缓释性能研究

目的:制备曲美他嗪固体分散体,使之具有缓释效果。方法:采用溶剂法制备固体分散体,以固体分散体的体外释放度为评价指标,单因素实验考察载体、制备方法、药物载体比例、致孔剂对曲美他嗪固体分散体缓释性能的影响,通过正交设计对处方及工艺进行优化,并对不同处方的固体分散体体外释药进行动力学拟合。应用DSC,XRD,FTIR考察固体分散体中曲美他嗪的存在状态及其与载体间的相互作用。结果:所得优化处方体外释药可持续24 h,药物体外释药行为符合一级动力学方程,药物释放以Fick扩散为主。曲美他嗪以微晶或无定形态存在于固体分散体中。结论:通过以上优化处方和工艺制备的曲美他嗪固体分散体具有良好的缓释效果及工艺重复性。     

西沙必利-HPMC固体分散体对其体外药物释放的促进作用

目的以羟丙基甲基纤维素(HPMC-E5 LV)为载体材料制备HPMC-西沙必利固体分散体,通过提高模型药物的溶解度来改善药物的体外释放.方法分别用乙醇和人工胃液将药物和载体材料溶解,使药物均匀分散在载体中, 减压干燥除去溶剂得到HPMC-西沙必利固体分散物; 用X射线粉末衍射法分别测定了纯载体材料、纯西沙必利、载体材料和西沙必利物理混合物以及载体材料和西沙必利固体分散体4:1的晶体衍射峰, 以确定是否有晶体存在; 分别考察纯西沙必利和HPMC-西沙必利固体分散体在水、人工胃液和人工肠液中的溶解度; 分别以纯西沙必利和载体材料和西沙必利固体分散体制备了西沙必利缓释片并考察了其在水和人工胃液中的药物释放.结果当载体与药物的比例达到4:1时,X 射线衍射实验表明药物的晶体峰已经消失, 形成无定型固体分散体; 与西沙必利原料药相比, 固体分散体中药物在人工胃液、水和人工肠液中的溶解度分别提高了239.4%、132.6% 和117.9%; 体外药物释放结果表明, 当以水和人工胃液为介质时,药物从固体分散体制备的缓释片中的释放速度要快于用纯原料药制备的缓释片中的释放速度, 体外释药规律可以用 Higuchi's 动力学方程描述.结论以HPMC为载体材料与西沙必利制成固体分散体, 可以通过改善药物的溶解度来加快缓释制剂中药物的溶出速度.     

硝苯地平缓释固体分散体颗粒的制备

目的：制备难溶性药物硝苯地平缓释固体分散体以便提高生物利用度。方法：采用固体分散技术（溶剂法）制备固体分散体,并进行体外释放度研究。结果：药物体外释药行为符合Higuchi方程;缓释结果与PVA用量和固体分散体的粒径有主要关系。     

电纺制备酮洛芬纳米纤维状固体分散体

以水难溶性药物酮洛芬为模型、聚乙烯吡咯烷酮为成纤基材,使用高压静电纺丝技术制各固体分散体.场扫描电镜观察到纳米纤维状固体分散体具有连续三维立体网状结构特征,X-射线衍射和差示扫描量热分析结果表明,药物以无定形或分子状态高度分散于聚合物基材中,傅里叶红外光谱分析结果证明,酮洛芬与聚乙烯吡咯烷酮之间能通过氢键相互作用.体外溶出结果表明,所制备的纳米纤维状固体分散体中酮洛芬能在30s内释放完全.     

Biodegradation and drug release of chitosan gel beads in subcutaneous air pouches of mice

Chitosan (CS) gel beads were prepared in 10% amino acid solution (pH 9) and implanted into air pouches (AP) prepared subcutaneously on the dorsal surface of mice. No inflammatory response was observed, and degradation of the beads in the AP increased as their degree of deacetylation decreased. Degradation could be altered by changing the nature of the CS or by increasing the CS concentration. The release of prednisolone (PS) in vivo from CS gel beads was similar to the release in vitro. When a suspension of PS was injected into the AP, the PS had almost completely disappeared 24 h after injection. Retention of PS in the AP was not increased by using a viscous CS solution. Alginate (Alg) gel beads, which were not degraded, released PS slowly into the AP over 3d. The in vitro release profile of PS using 1% CS (deacetylation: 70% (7B) and 80% (8B)) and 1.5% CS (deacetylation: 90% (9B)) gel beads was similar to that with Alg gel beads. However, the in vivo release of PS was affected by the degradability of the gel beads. CS7B and 8B (1%) gel beads had released PS into the AP earlier than 3 d according to their rate of degradation. CS9B (1.5%) gel beads were not degraded after 3 d and went on to release PS into the AP for 3 d similar to the release profile of Alg gel beads. CS9B (2%) gel beads were also not degraded after 3 d and the release of PS from these beads into the AP was sustained; 76% and 27% of administered PS remained in the gel beads after 1 and 3 d, respectively. Therefore, degradation and drug release of CS gel beads can be controlled by changing the structure of the gel matrix, which appears to make these beads a promising biodegradable vehicle for sustained drug delivery.     

龟板水提物缓释微球的制备及其特性

目的：制备高包封率的龟板水提物缓释微球。方法：分别采用海藻酸钙凝胶珠、海藻酸钙-壳聚糖微胶囊和海藻酸钙-羧甲基纤维素钠微胶囊体系制备龟板水提物缓释微球,并考察其外观形态、包封率和体外释药等特性。结果：制得的龟板-海藻酸钙凝胶珠、龟板-海藻酸钙—壳聚糖微球和龟板-海藻酸钙-羧甲基纤维素钠微球外观圆整,表面光滑,且粒径均匀;包封率分别是46．7％、49．9％和82．3％;海藻酸钙凝胶珠有明显的突释现象,海藻酸钠—壳聚糖微球的突释现象和缓释效果有所改善,而海藻酸钙-羧甲基纤维素钠微球无突释现象,其缓释可达14小时以上。结论：龟板-海藻酸钙-羧甲基纤维素钠微球包封率高,同时具有优良的缓释性能。     

In vitro evaluation of chitosan coated- and uncoated-calcium alginate beads containing methyl salicylate-lactose physical mixture

Context: Methyl salicylate–lactose physical mixture (1:1 and 1:1.5 ratios) was incorporated into calcium alginate beads by a coacervation method involving an ionotropic gelation/polyelectrolyte complexation approach.

Objectives: This study aims to determine the influence of chitosan coating over the beads on drug entrapment efficiency (DEE) and release characteristics in artificial saliva compared to that of the uncoated beads.

Results and discussion: Changes in formulation parameters (gelation time, concentrations of Ca²⁺ and alginate) resulted in decrease in DEE of chitosan-uncoated beads (p?<?0.05). This is due to the combined effects of drug leach-out from the physical mixture by Ca²⁺ ions, alginate gel matrix cross-linking and free drug diffusion from chitosan-uncoated beads. However, an increment in the DEE was seen for chitosan-coated beads. A rapid drug release profile was noted for uncoated beads, but for chitosan-coated beads a sustained release profile was depicted depending upon the coating conditions. Chitosan-coated beads had reduced swelling and erosion properties and thus behaved as a physical barrier to drug release. Shifting from anomalous transport type to Fickian transport confirmed the formation of physical barrier onto chitosan-coated beads.

Conclusion: Calcium alginate beads could be used as a controlled-release system for methyl salicylate–lactose physical mixture.     

Preparation of dual crosslinked alginate-chitosan blend gel beads and in vitro controlled release in oral site-specific drug delivery system

Alginate-chitosan (ALG-CS) blend gel beads were prepared based on Ca2+ or dual crosslinking with various proportions of alginate and chitosan. The homogeneous solution of alginate and chitosan was dripped into the solution of calcium chloride; the resultant Ca2+ single crosslinked beads were dipped in the solution of sodium sulfate sequentially to prepare dual crosslinked beads. The dual crosslinkage effectively promoted the stability of beads under gastrointestinal tract conditions. The sustained release profiles of single and dual crosslinked gel beads loaded bovine serum albumin (BSA), a model protein drug, were investigated in simulated gastric fluid (SGF), simulated intestinal fluid (SIF) and simulated colonic fluid (SCF). In SGF, compared to Ca2+ single crosslinked beads, from which BSA released fast and the cumulative drug release percentages were about 80% of all formations in 4 h, the BSA total release from dual crosslinked gel beads was no more than 3% in 8 h. In SIF and SCF, Ca2+ single crosslinked beads were disrupted soon associating with the fast drug release. As to the dual crosslinked beads, the BSA total release from the ALG-CS mass ratio 9:1 (81.24%) was higher than that of 7:3 and 5:5 (less than 60%) in 8 h in SIF; the BSA release from all beads was much faster in SCF than in SIF. The dual crosslinked beads incubated in gastrointestinal tract conditions, the BSA cumulative release of ALG-CS mass ratios 9:1, 7:3 and 5:5 were respectively 2.35, 1.96, 1.76% (in SGF 4 h), 82.86, 78.83, 52.91% (in SIF 3 h) and 97.84, 96.81, 87.26% (in SCF 3 h), which suggested that the dual crosslinked beads have potential small intestine or colon site-specific drug delivery property.     

Development and evaluation of polyethyleneimine-treated calcium alginate beads for sustained release of diltiazem

The objective of this investigation is to develop a multi-unit sustained release dosage form of a water soluble drug from a completely aqueous environment avoiding the use of any organic solvent. The drug was complexed with resin and calcium alginate or polyethyleneimine-treated calcium alginate beads loaded with the resinate were prepared by a ionic/polyelectrolyte complexation method. The effect of different formulation variables on the characteristics of the beads was investigated. Although the drug release from spherical and smooth-surfaced calcium alginate beads in both acidic and alkaline dissolution media were slower than those obtained from plain resinate, none of the variables were found to prolong the drug release considerably due to rapid swelling and disintegration of calcium alginate beads in alkaline medium. On the other hand, drug release from polyethyleneimine-treated calcium alginate beads in acidic medium did not increase appreciably following a burst release. However, in alkaline medium, the drug release was found to increase gradually and extend over a different period of time depending on the intensity of polyethyleneimine treatment. Scanning electron micrographs revealed the formation of a dense membrane around the resinate-loaded calcium alginate matrix. The membrane appeared to be responsible for reduced swelling and protracted disintegration of the beads resulting in slow release of the drug. The results indicate that sustained release of a water soluble drug from polyethyleneimine-treated calcium alginate beads could be achieved by adjusting the formulation variables.     

Development and evaluation of polyethyleneimine-treated calcium alginate beads for sustained release of diltiazem

The objective of this investigation is to develop a multi-unit sustained release dosage form of a water soluble drug from a completely aqueous environment avoiding the use of any organic solvent. The drug was complexed with resin and calcium alginate or polyethyleneimine-treated calcium alginate beads loaded with the resinate were prepared by a ionic/polyelectrolyte complexation method. The effect of different formulation variables on the characteristics of the beads was investigated. Although the drug release from spherical and smooth-surfaced calcium alginate beads in both acidic and alkaline dissolution media were slower than those obtained from plain resinate, none of the variables were found to prolong the drug release considerably due to rapid swelling and disintegration of calcium alginate beads in alkaline medium. On the other hand, drug release from polyethyleneimine-treated calcium alginate beads in acidic medium did not increase appreciably following a burst release. However, in alkaline medium, the drug release was found to increase gradually and extend over a different period of time depending on the intensity of polyethyleneimine treatment. Scanning electron micrographs revealed the formation of a dense membrane around the resinate-loaded calcium alginate matrix. The membrane appeared to be responsible for reduced swelling and protracted disintegration of the beads resulting in slow release of the drug. The results indicate that sustained release of a water soluble drug from polyethyleneimine-treated calcium alginate beads could be achieved by adjusting the formulation variables.     

Ca-alginate microspheres encapsulated in chitosan beads

Chitosan beads (CBs) incorporating Ca-alginate microspheres (CAMs), containing a drug, were prepared as an oral sustained delivery system. Stable and monodisperse Ca-alginate microspheres loaded with drug were obtained by a membrane emulsification method. The Ca-alginate microspheres were encapsulated in chitosan beads by the ionotropic gelation method with a polyelectrolyte complex reaction between two oppositely charged polyions. The surface and internal characteristics of the beads were improved by ionic cross-linking in tripolyphosphate (TPP) solution adjusted to pH 5.0. The release experiments were performed using lidocaine·HCl (cationic drug) and sodium salicylate (anionic drug) as model drugs. Initial release of drugs depended on the degree of swelling. Ca-alginate microspheres encapsulated in chitosan beads were superior to both drug-loaded CBs and CAMs beads for sustained release because they had a three-layer composition; a calcium alginate core bounded by an inter-phasic chitosan-alginate membrane, which itself was surrounded by a layer of chitosan-TPP.     

Ca-alginate microspheres encapsulated in chitosan beads

Chitosan beads (CBs) incorporating Ca-alginate microspheres (CAMs), containing a drug, were prepared as an oral sustained delivery system. Stable and monodisperse Ca-alginate microspheres loaded with drug were obtained by a membrane emulsification method. The Ca-alginate microspheres were encapsulated in chitosan beads by the ionotropic gelation method with a polyelectrolyte complex reaction between two oppositely charged polyions. The surface and internal characteristics of the beads were improved by ionic cross-linking in tripolyphosphate (TPP) solution adjusted to pH 5.0. The release experiments were performed using lidocaine.HCl (cationic drug) and sodium salicylate (anionic drug) as model drugs. Initial release of drugs depended on the degree of swelling. Ca-alginate microspheres encapsulated in chitosan beads were superior to both drug-loaded CBs and CAMs beads for sustained release because they had a three-layer composition; a calcium alginate core bounded by an inter-phasic chitosan-alginate membrane, which itself was surrounded by a layer of chitosan-TPP.     

Effect of chondroitin sulfate on the biodegradation and drug release of chitosan gel beads in subcutaneous air pouches of mice

Chitosan (CS) gel beads were prepared in 10% amino acid solution (pH 9) and modified by forming an electrostatic complex between the amino group of CS and the carboxyl group of chondroitin sulfate (Cho). Modification of the CS gel matrix by Cho inhibited the in vitro release of prednisolone (PS) from the gel beads. CS gel beads modified by Cho (CS-Cho) were implanted into air pouches (AP) prepared subcutaneously on the dorsal surfaces of mice. No inflammatory response was observed. The in vivo release of PS from CS-Cho gel beads and their biodegradation in the AP was slower than beads without Cho treatment. After 28 days of implantation, CS-Cho gel beads (deacetylation of CS: 90%) were still detectable, although they had become softer and smaller. Modification of the CS gel matrix by Cho controls the biodegradation of the beads and the release of the drug. This effect makes these beads a promising biocompatible and biodegradable vehicle for sustained drug delivery.     

Preparation and release characteristics of polymer-reinforced and coated alginate beads

Polymeric reinforcement and coatings of alginate beads were carried out to control the release rate of drug from alginate beads. A poorly water-soluble ibuprofen (IPF) was selected as a model drug. A commercially available Eudragit^® RS100 was also used as a polymer. Effects of polymeric contents, the presence of plasticizers and amount of drug loading on the release rate of drug were investigated. The release rate of drug from alginate beads in the simulated gastric fluid did not occur within 2 h but released immediately when dissolution media were switched to the simulated intestinal fluid. No significant difference of release rate from polymer-reinforced alginate bead without plasticizers was observed when compared to plain (simple) beads. However, the release rate of drug from polymer-reinforced alginate beads was further sustained and retarded when aluminium tristearate (AT) as a plasticizer was added to polymer. However, polyethylene glycol 400 (PEG400) did not change the release rate of drug from alginate beads although PEG400 was used to improve dispersion of polymer and sodium alginate, and plasticize Eudragit^® RS100 polymer. The presence of plasticizer was crucial to reinforce alginate gel matrices using a polymer. As the amount of drug loading increased, the release rate of drug increased as a result of decreasing effects of polymer contents in matrices. The significantly sustained release of drug from polymer-coated alginate beads occurred as the amount of polymer increased because the thickness of coated membrane increased so that cracks and pores of the outer surface of alginate beads could be reduced. The sustained and retarded action of polymer-reinforced and coated beads may result from the disturbance of swelling and erosion (disintegration) of alginate beads. From these findings, polymeric-rein-forcement and coatings of alginate gel beads can provide an advanced delivery system by retarding the release rate of various drugs.