壳聚糖及其衍生物在肽类口服给药系统的应用

壳聚糖作为药用辅料在药剂领域中的地位愈加显著,将聚β１→４Ｄ－葡萄糖胺的２位氨基进行修饰,可获得具不同功能的壳聚糖类衍生物,对于口服氨基酸第系统来说,最主要的是克服胃肠道的吸收屏障及酶屏障,未经化学修饰的壳聚糖对肽类药物具有一定的促渗作用。将抑制剂固定于聚合物结构内则对肠肽酶对肽类的降解产生保护作用,胰丝氨酸蛋白酶的降解作用可被竞争性抑制剂如Ｂｏｗｍａｎ－Ｂｉｒｋ抑制剂所抑制,而金属肽酶的降解作用则可被壳聚糖－ＥＤＴＡ复合物等性质较复杂的壳聚糖衍生物所抑制,而且,由于壳聚糖及其大部分衍生物都具有粘膜粘附特性,多肽药物的吸收前代谢也大大降低,综合以上因素,壳聚糖及其衍生物可显著提高某些肽类药物如胰岛素、降钙素及布舍瑞林口服给药的生物利用度,是肽类口服给药系统中的一类重要辅料。     

壳聚糖及其衍生物在胰岛素口服中的应用

壳聚糖及其衍生物可以提高胰岛素的口服生物利用度,应用广泛,发展前景广阔。本文介绍壳聚糖及其衍生物在促进胰岛素口服方面的应用进展。     

壳聚糖及衍生物在药物制剂中的应用

目的探讨壳聚糖及衍生物在药物制剂中的应用效果。方法通过对有关壳聚糖及其衍生物相关的文章进行搜索和检查,对其制备方式和在药物制剂中的应用加以准确的分析和探讨,对其有关参考文献结果和结论进行准确分析,进一步总结,从而做出准确的分析结果。结果壳聚糖具有很好的生物相容性,能够达到较强的生物降解性,同时无不良反应,并且容易成膜,在医学研究领域,壳聚糖具有较强的应用作用,能够用于缓释和控释的药物制剂,通过对其物理化学特性进行详细的分析探讨,能够促进多肽类、蛋白质药物的很好吸收。结论壳聚糖及其衍生物在应用过程中所发挥的缓释和控释的作用非常明显,能够有效的缓释和均衡药物速率,减少药物在使用过程中可能会对人体产生的毒害作用,值得在临床上推广应用。     

壳聚糖及其衍生物包覆脂质体对胰岛素肠道吸收的影响

目的考察壳聚糖及其衍生物包覆脂质体对胰岛素肠道吸收的影响。方法采用逆相蒸发制备胰岛素脂质体；采用在体肠灌流法研究壳聚糖及其衍生物包覆胰岛素脂质体的肠道吸收；用酶-苯酚法测定血糖值；用放射免疫法测定血清和肠组织中胰岛素含量。结果壳聚糖(CH)、壳聚糖-EDTA轭合物(CEC)包覆胰岛素脂质体和CH-CEC双层包覆胰岛素脂质体的最佳吸收部位均集中在十二指肠，胰岛素溶液的最佳吸收部位在结肠，而未包覆胰岛素脂质体和N-三甲基壳聚糖盐酸盐(TMC)包覆胰岛素脂质体的最佳吸收部位尚不能确定。在各肠段中，以CH-CEC双层包覆胰岛素脂质体的吸收最佳。结论壳聚糖及其衍生物包覆脂质体能促进胰岛素经肠道吸收，并可提高其在肠道中的稳定性。     

酰化改性壳聚糖的合成及其性质考察

目的探讨疏水性壳聚糖衍生物作为口服药用不溶性骨架材料的可行性。方法以N-邻苯二甲酰壳聚糖为中间体,合成C6位被3种不同长度脂肪链完全酰化的壳聚糖衍生物,采用IR、1H-NMR、元素分析等方法对其结构进行表征;采用固定圆锥法测定壳聚糖衍生物流动性、压缩成形性及其在不同溶剂中的溶解性;以茶碱为模型药物,考察壳聚糖衍生物用于控制药物释放的可行性并初步探讨其释药机制。结果成功合成了3种壳聚糖衍生物并对其结构进行了表征;3种衍生物在有机溶剂中的溶解度显著提高,且具有很好的流动性和压缩成形性;单独使用该类衍生物制备的茶碱不溶性骨架片可显著延长释放时间至30 h,其释药机制以扩散为主,符合Huguch i方程。结论酰化改性壳聚糖衍生物加工性能和缓释作用良好,可用于口服不溶性骨架制剂,是一种良好的新型辅料。     

壳聚糖及其衍生物在药学研究领域的新进展

介绍了壳聚糖及其衍生物在药学领域的最新研究进展,重点阐述了壳聚糖及其衍生物的生物黏附性、促吸收作用和酶抑制剂的功能载体作用,及其在新型给药系统开发中的应用.     

壳聚糖衍生物——N-三甲基壳聚糖的促吸收作用研究进展

目的:探讨壳聚糖衍生物——N-三甲基壳聚糖促吸收作用的研究进展。方法:查阅国内外有关N-三甲基壳聚糖促吸收作用的机制、影响因素及应用的文献,并进行分析、总结。结果:N-三甲基壳聚糖可增加细胞旁路途径的跨膜转运,具有促进药物吸收的作用。结论:N-三甲基壳聚糖有望作为一种有效促吸收剂应用于药物制剂。     

壳聚糖衍生物及其胶束：特性、功能化修饰和在药物传递系统中的应用

壳聚糖是一种天然多糖,具有无毒、可生物降解、生物相容性等诸多优点,但水溶性差的自身特点限制了其在药剂学中的应用,而其经合理的结构设计、修饰和优化,可获得性能良好的两亲性壳聚糖衍生物,这些衍生物在水溶液中能自组装成具有良好药物传输性能（如载药量、稳定性、刺激敏感性、靶向性等）的胶束,并被广泛应用于构建药物传递系统,以改善药物的溶解性、靶向性、生物利用度及耐药性．降低药物的毒副作用。综述壳聚糖衍生物结构对其胶束药物传输性能的影响以及壳聚糖衍生物及其胶束的功能化修饰和在药物传递系统中的应用。     

肽类药物的口服吸收促进剂氯化N-三甲基壳聚糖

对氯化N-三甲基壳聚糖的制备、理化性质、促吸收机制、细胞毒性评价及制剂等方面作一综述。氯化N-三甲基壳聚糖是壳聚糖的部分季铵化衍生物，能溶于中性及碱性环境中，可作为肽类药物的口服吸收促进剂。     

两亲性壳聚糖衍生物在药物递送中的研究进展

壳聚糖是一种来源丰富的碱性多糖,具有良好的生物相容性和生物可降解性,但是其差的溶解性限制了壳聚糖在医药领域的应用。为了提高壳聚糖的溶解性,研究者对壳聚糖进行两亲性改性,通过选择不同的亲水、疏水基团,设计合成了两亲性壳聚糖衍生物。并利用其在水溶液中的自组装性能,形成两亲性壳聚糖纳米粒,用于多种药物的递送,以达到增加药物溶解性、稳定性、降低药物毒性和提高生物利用度等目的。本文综述了两亲性壳聚糖衍生物的合成方法,以及其在药物递送系统中的应用。     

壳聚糖及其衍生物在药物递送中的研究进展

壳聚糖是自然界中存在的唯一的带正电的碱性氨基多糖,具有来源丰富、无毒、低免疫原性、良好的生物可降解性和生物相容性等优点。壳聚糖的活性氨基和羟基,经各种化学修饰如羧基化、巯基化、季铵化、疏水修饰、长循环修饰和靶向修饰,可获得具有特殊功能特性的衍生物,广泛用作药物和基因的载体材料。是近年来药剂学领域的研究热点。本文就近年来壳聚糖及其衍生物在药物递送中的研究进展作一综述。     

壳聚糖及其衍生物在口服制剂中的应用

壳聚糖及其衍生物具有优良的生物特性及物理化学性质，在药物制剂中有广阔的应用前景。在调研国内外相关资料的基础上。结合实际工作对目前正在研究并取得一定进展的壳聚糖及其衍生物在口服药物制剂中的应用作简要综述。     

Chitosan-Based Particles as Controlled Drug Delivery Systems

Chitosan, a natural-based polymer obtained by alkaline deacetylation of chitin, is nontoxic, biocompatible, and biodegradable. These properties make chitosan a good candidate for conventional and novel drug delivery systems. This article reviews the approaches aimed to associate bioactive molecules to chitosan in the form of colloidal structures and analyzes the evidence of their efficacy in improving the transport of the associated molecule through mucosae and epithelia. Chitosan forms colloidal particles and entraps bioactive molecules through a number of mechanisms, including chemical crosslinking, ionic crosslinking, and ionic complexation. A possible alternative of chitosan by the chemical modification also has been useful for the association of bioactive molecules to polymer and controlling the drug release profile. Because of the high affinity of chitosan for cell membranes, it has been used as a coating agent for liposome formulations. This review also examines the advances in the application of chitosan and its derivatives to nonviral gene delivery and gives an overview of transfection studies that use chitosan as a transfection agent. From the studies reviewed, we concluded that chitosan and its derivatives are promising materials for controlled drug and nonviral gene delivery.     

Effect of chitosan on gastrointestinal absorption of water-insoluble drugs following oral administration in rats

Chitosan is widely used as a dietary weight-loss supplement in Japan. In the present study, we examined the effect of chitosan on the gastrointestinal absorption profiles of the water-insoluble drugs, indomethacin and griseofulvin, and the water-soluble drugs, acetaminophen and cephalexin, after oral administration in rats. Rats received oral administration of chitosan (5 mg/kg or 25 mg/kg) dissolved in 5% acetic acid or vehicle 15 min before oral administration of each drug. Chitosan at a dose of 25 mg/kg, but not 5 mg/kg, significantly decreased the plasma concentrations of indomethacin and griseofulvin after administration as a suspension with a significant delay of the time to reach maximum concentration compared to the corresponding control values (vehicle-pretreated rats). However, pretreatment of chitosan (25 mg/kg) did not change the pharmacokinetics of indomethacin administered as a solution. Further, the same dose of chitosan had no effect on the pharmacokinetics of acetaminophen. The gastrointestinal absorption profile of an amino-beta-lactam antibiotic, cephalexin, which is actively absorbed via carrier-mediated transport system, was also unchanged. The present findings at least suggest the possibility that chitosan at high dose reduces the gastrointestinal absorption of water-insoluble drugs such as indomethacin and griseofulvin, but not water-soluble drugs, by diminishing the surfactant-like effect of bile acids.     

Chitosan-based particles as controlled drug delivery systems

Chitosan, a natural-based polymer obtained by alkaline deacetylation of chitin, is nontoxic, biocompatible, and biodegradable. These properties make chitosan a good candidate for conventional and novel drug delivery systems. This article reviews the approaches aimed to associate bioactive molecules to chitosan in the form of colloidal structures and analyzes the evidence of their efficacy in improving the transport of the associated molecule through mucosae and epithelia. Chitosan forms colloidal particles and entraps bioactive molecules through a number of mechanisms, including chemical crosslinking, ionic crosslinking, and ionic complexation. A possible alternative of chitosan by the chemical modification also has been useful for the association of bioactive molecules to polymer and controlling the drug release profile. Because of the high affinity of chitosan for cell membranes, it has been used as a coating agent for liposome formulations. This review also examines the advances in the application of chitosan and its derivatives to nonviral gene delivery and gives an overview of transfection studies that use chitosan as a transfection agent. From the studies reviewed, we concluded that chitosan and its derivatives are promising materials for controlled drug and nonviral gene delivery.     

壳聚糖在靶向制剂中的应用进展

壳聚糖是一种天然高分子化合物，壳聚糖及其衍生物具有优良的生物相容性和生物可降解性，在制药业有广阔的应用前景。综述了近几年来壳聚糖及其衍生物在靶向制剂中的应用。     

Chitosan and its derivatives in mucosal drug and vaccine delivery.

Numerous studies have demonstrated that chitosan and their derivatives (N-trimethyl chitosan, mono-N-carboxymethyl chitosan) are effective and safe absorption enhancers to improve mucosal (nasal, peroral) delivery of hydrophylic macromolecules such as peptide and protein drugs and heparins. This absorption enhancing effect of chitosans is caused by opening of the intercellular tight junctions, thereby favouring the paracellular transport of macromolecular drugs. Chitosan nano- and microparticles are also suitable for controlled drug release. Association of vaccines to some of these particulate systems has shown to enhance the antigen uptake by mucosal lymphoid tissues, thereby inducing strong systemtic and mucosal immune responses against the antigens. The aspecific adjuvant activity of chitosans seems to be dependent on the degree of deacetylation and the type of formulation. From the studies reviewed it is concluded that chitosan and chitosan derivatives are promising polymeric excipients for mucosal drug and vaccine delivery.     

In vitro and In vivo evaluation of positively charged liposaccharide derivatives as oral absorption enhancers for the delivery of anionic drugs

Oral delivery of hydrophilic, ionisable drugs remains a major challenge in drug development and a number of active pharmaceuticals fail to reach the market of oral drugs because of a lack of absorption and/or stability issues. One possible approach to improving the bioavailability of such drug candidates is to increase their lipophilicity, which is a key parameter in the permeation across cell membranes. However, modifying the chemical structure by adding lipid residues often results in changes in activity. With ionised molecules, ion‐pairing can be considered to associate charged lipid moieties with the parent drug without altering its structure and therefore activity. This study presents the results of in vitro and in vivo evaluation of a series of synthetic, positively charged liposaccharide derivatives combined with an anionic model drug, piperacillin. The antimicrobial activity, plasma stability, Caco‐2 cell permeability and oral absorption of the conjugates were assessed. Increases in apparent permeability were observed in vitro for three of the tested formulations, while retaining the antibacterial activity of the drug. However, the in vivo intestinal absorption of piperacillin formulated with the liposaccharide derivatives was found unchanged, possibly due to molecular dissociation, early degradation or structural differences between the intestinal epithelium and cultured monolayers. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2333–2342, 2010     

Influence of chitosan and its glutamate and hydrochloride salts on naproxen dissolution rate and permeation across Caco-2 cells

Chitosan and its glutamate and hydrochloride salts were evaluated for their efficacy in improving the dissolution behaviour of naproxen (a poorly water-soluble antiinflammatory drug) and its transport in vitro across Caco-2 cell monolayers. Drug-polymer physical mixtures and coground products, prepared at two different w/w ratios (30/70 and 10/90), were characterized by differential scanning calorimetry, X-ray powder diffractometry, scanning electron microscopy, and tested for dissolution properties. Coground systems were more effective than physical mixtures in improving drug dissolution and chitosan base, in spite of its lower water solubility, showed higher solubilizing power than its salts. According to the solid state analyses results, this effect was directly related to its stronger amorphizing power. Transport studies showed that only coground mixtures with chitosan glutamate salt allowed a significant drug apparent permeability improvement; however, they did not exhibit appreciable effects on the Caco-2 tight junctions (measured by the trans-epithelial electrical resistance variations), thus indicating that their enhancer effect was mainly due to an improved naproxen transport by transcellular passive diffusion rather than through the paracellular route. The direct compression properties and antiulcerogenic activity together with the demonstrated dissolution and permeation enhancer abilities toward naproxen make chitosan glutamate an optimal carrier for developing fast-action oral solid dosage forms of this drug.     

Chitosan: some pharmaceutical and biological aspects--an update

Chitosan, a natural polysaccharide, is being widely used as a pharmaceutical excipient. It is obtained by the partial deacetylation of chitin, the second most abundant natural polymer. Chitosan comprises a series of polymers varying in their degree of deacetylation, molecular weight, viscosity, pKa etc. The presence of a number of amino groups permit chitosan to chemically react with anionic systems, thereby resulting in alteration of physicochemical characteristics of such combinations. Chitosan has found wide applicability in conventional pharmaceutical devices as a potential formulation excipient, some of which include binding, disintegrating and tablet coating properties. The polymer has also been investigated as a potential adjuvant for swellable controlled drug delivery systems. Use of chitosan in novel drug delivery as mucoadhesive, gene and peptide drug administration via the oral route as well as its absorption enhancing effects have been explored by a number of researchers. Chitosan exhibits myriad biological actions, namely hypocholesterolemic, antimicrobial and wound healing properties. Low toxicity coupled with wide applicability makes it a promising candidate not only for the purpose of drug delivery for a host of drug moieties (antiinflammatories, peptides etc.) but also as a biologically active agent. It is the endeavour of the present review to provide an insight into the biological and pharmaceutical profile of chitosan. Various investigations carried out recently are reported, although references to research performed on chitosan prior to the recent reviews have also been included, where appropriate.