生物医用高分子材料在药物控释系统中的应用

药物控制释放体系是继传统载药体系发展起来的一种新型的疾病治疗体系。生物医用高分子材料作为药物控释载体的研究逐渐成为热点之一。近年来,随着研究的深入,生物医用高分子材料在药物控释系统中的运用得到了广泛的发展。本文简要介绍了常用天然医用高分子材料如胶原、纤维素以及环糊精和合成医用高分子材料如聚乳酸、聚酸酐等在药物控释系统中的应用,并对这类材料的应用进行了展望。     

高分子药用控释材料研究进展

本文综述了高分子药用控释材料的性能、分类及其应用;并介绍了其发展方向。     

微生物发酵聚羟基烷酸（PHA）研究进展

聚羟基烷酸是一类生物可降解塑料,具有良好的应用前景,正成为全世界关注的研究热点,它是许多微生物在Ｃ,Ｎ源失衡条件下作为胞内碳源和能源储存物而大量积累产生的。本文着重对国内外微生物发酵ＰＨＡ研究水平和培养方法进行了简要介绍,并对发展方向作了探讨。     

替莫唑胺局部缓释制剂的研究进展

近年来,为更有效地发挥替莫唑胺对神经胶质瘤的治疗活性,局部、缓释给药成为替莫唑胺的研究热点。本文简述了几种研发中的替莫唑胺的局部缓释新制剂,其中替莫唑胺-聚酸酐缓释微球(TMZ-pCPP：SA)由于聚酸酐表面溶蚀等特性,具有良好的缓释特性,鼠颅内植入试验显示,比口服替莫唑胺具有更好的治疗效果,因此替莫唑胺-聚酸酐缓释微球作为颅内缓释制剂具有极为光明的前景。     

刺激响应型水凝胶用于药物控释的研究进展

水凝胶作为一类与人体组织高度相似的聚合物材料,在生物医学领域已得到广泛的应用.相比传统型水凝胶,刺激响应型水凝胶可在外界环境刺激下表现出溶胀或降解特性,常作为药物控制释放的载体,在不同的组织环境中实现了水凝胶网络结构的形成或瓦解,提高了药物的组织滞留率或实现其控制释放.笔者介绍了刺激响应型水凝胶作为药物控制释放系统的应...     

聚羟基脂肪酸酯 (PHA) 及其共混纤维研究进展

聚羟基脂肪酸酯(PHA)是代表性的生物基可降解高分子,其种类超过150种,性能多样、可调。文中综述了PHA的研究概况及潜在应用,介绍了四代商业化PHA的性质及其与其他生物基可降解材料形成共混纤维的研究进展。     

利用转基因植物合成生物可降解材料聚羟基脂肪酸酯

聚羟基脂肪酸酯 (polyhydroxyalkanoates,PHAs)因其完全的生物可降解性、良好的物理加工特性以及生物相容性使其应用前途十分广泛。本文综述了利用转基因植物合成PHAs的研究概况和存在问题 ,进一步探讨了其解决方法。     

聚苹果酸及其衍生物的制备与应用研究进展

摘要：天然和合成聚合物因优良的特性引起了越来越多研究者的兴趣,并已被广泛用于人类的日常生活中。聚苹果酸（Polymalic acid,PMLA）一种天然的高分子聚酯材料,具有良好的生物相容性和完全生物降解性,其衍生物同样具有优异的生物学性能,被广泛应用于众多领域中。本文就聚苹果酸及其衍生物的结构、性质和合成方法进行了概述,并全面总结了其在制药和其他领域的应用研究现状,最后对未来发展方向进行了展望。     

壳聚糖／海藻酸钠微囊作为口服控释制剂载体的研究

壳聚糖与海藻酸钠通过聚电解质络合反应制备成壳聚糖 /海藻酸钠微囊 ,其粒径为 1mm左右。以干扰素为模型药物 ,其包封率达 90 %以上。同时还研究了在不同 pH条件下 ,干扰素的控制释放情况。结果表明 :微囊在模拟胃液 (pH 1.0 )中 3h的药物释率仅为≤ 5 % ,但在模拟肠液 (pH 7.4 )中 3h ,80 %～ 90 %的药物被释放。     

生物可降解塑料的必酶生产研究进展

近十几年来,随着化学合成塑料造成环境污染的日趋严重,微生物合成生物可降解塑料的研究受到人们的广泛重视。聚羟基烷酸（ｐｏｌｙｈｙｄｒｏｘｙａｌｋａｎｏａｔｅｓ;ＰＨＡ）具有与化学合成塑料相似的性质,能拉丝、压模、注塑等,而且具有合成塑料所没有的特殊性能;如利用其生物相容性可作为外科手术缝线、人造血管和骨骼代用品,术后无需取出。因而在工业、农业、医药和环保等行业都具有广阔的应用前景。 目前,微生物发酵生产是获得生物可降解塑料的主要途径。对ＰＨＡ研究最多的是聚羟基丁酸（ｐｏｌｙ－３－ｈｙｄｒｏｘｙｂｕ…     

Biocompatible controlled release polymers for delivery of polypeptides and growth factors

The development of biocompatible, controlled release systems for macromolecules has provided the opportunity for researchers and clinicians to target and deliver, on site, biologically active factors. This advance has also facilitated the purification and characterization of a number of important biomolecules. These systems include controlled release delivery systems which release proteins through porous polymer matrices, degradable polymeric delivery systems, and modulated polymer release systems. These areas of research will be reviewed with regards to their design, release kinetics, and biocompatibilities. The utilization of these systems to release such biologically important polypeptides as growth factors (e.g., fibroblast growth factor, epidermal growth factor, transforming growth factor-B) as well as a number of important inhibitory factors (e.g., nitrosoureas, angiogenesis inhibitors) in both in vivo and in vitro studies will be discussed.     

Development and in vitro evaluation of an oral floating matrix tablet formulation of diltiazem hydrochloride

The purpose of this research was to prepare a floating drug delivery system of diltiazem hydrochloride (DTZ). Floating matrix tablets of DTZ were developed to prolong gastric residence time and increase its bioavailability. Rapid gastrointestinal transit could result in incomplete drug release from the drug delivery system above the absorption zone leading to diminished efficacy of the administered dose. The tablets were prepared by direct compression technique, using polymers such as hydroxypropylmethylcellulose (HPMC, Methocel K100M CR), Compritol 888 ATO, alone or in combination and other standard excipients. Sodium bicarbonate was incorporated as a gas-generating agent. The effects of sodium bicarbonate and succinic acid on drug release profile and floating properties were investigated. A 3² factorial design was applied to systematically optimize the drug release profile. The amounts of Methocel K100M CR (X₁) and Compritol 888 ATO (X₂) were selected as independent variables. The time required for 50% (t₅₀) and 85% (t₈₅) drug dissolution were selected as dependent variables. The results of factorial design indicated that a high level of both Methocel K100M CR (X₁) and Compritol 888 ATO (X₂) favors the preparation of floating controlled release of DTZ tablets. Comparable release profiles between the commercial product and the designed system were obtained. The linear regression analysis and model fitting showed that all these formulations followed Korsmeyer and Peppas model, which had a higher value of correlation coefficient (r). While tablet hardness had little or no effect on the release kinetics and was found to be a determining factor with regards to the buoyancy of the tablets. Published: September 7, 2007     

球霰石在药物装载及控释中的应用

目前,基于纳米材料的药物递送系统是生物医学交叉领域的研究热点,其核心问题之一是载药及控释,关键抓手之一是载体。球霰石是碳酸钙的一种晶型,呈多孔状,有来源丰富、制备容易、成本低、装载程序简单、生物相容性好等诸多突出优点。通过合适的制备策略而得到的球霰石载体,不仅可以高效、稳定地携载药物,还可以获得理想的控释效果。近年来,基于球霰石载药及控释的研究取得了一定的新成果。本文介绍了球霰石的基本特性,特别对载药性能、控释能力及其调控,以及在细胞和动物水平的相关应用研究进展做了归纳、总结,并进行了比较及评述。此外,还对其存在的问题和发展趋势做了探讨。     

生物相容透皮给药微针治疗浅表肿瘤

复杂的肿瘤微环境导致抗肿瘤药物在肿瘤组织内递送效率低下,严重阻碍了药物对浅表肿瘤的治疗效果。生物相容透皮给药微针凭借较高的机械强度,刺穿皮肤角质层,将微针内的药物递送至浅表肿瘤组织内,提高生物利用度,改善静脉注射、口服给药的肝肾毒性等问题。本文介绍了生物相容透皮给药微针的设计及其在癌症化疗、光动力治疗、光热治疗、免疫治疗、基因治疗等领域的研究进展,对浅表肿瘤的微创、局部递药和精准、高效治疗具有重要指导意义。     

Colon Specific Delivery of Indomethacin: Effect of Incorporating pH Sensitive Polymers in Xanthan Gum Matrix Bases

In the present study, an attempt has been made to design controlled release colon-specific formulations of indomethacin by employing pH responsive polymers Eudragit (L100 or S100) in matrix bases comprised of xanthan gum. The prepared tablets were found to be of acceptable quality with low-weight variation and uniform drug content. In vitro release studies indicated rapid swelling and release of significant percentage of drug in the initial period from matrix tablets composed of xanthan gum alone. Addition of pH responsive polymers Eudragit (L100 or S100) to xanthan gum matrix resulted in negligible to very low drug release in the initial period in acidic to weakly acidic medium. Furthermore, with increase in pH of the dissolution medium due to dissolution of Eudragit L100/Eudragit S100 that resulted in the formation of a porous matrix, faster but controlled drug release pattern was observed. Thus, a sigmoidal release pattern was observed from the designed formulations suitable for colonic delivery. Drug release mechanism in all cases was found to be of super case II type, indicating erosion to be the primary cause of drug release. Since the drug release from almost all the matrix bases in the initial phase was negligibly low and followed with controlled release for about 14–16 h, it was concluded that a matrix design of this composition could have potential applications as a colon-specific drug delivery device with additional advantage of easy scale-up and avoidance of all-or-none phenomenon associated with coated colon-specific systems.     

Preparation and characteristics of high-amylose corn starch/pectin blend microparticles: A technical note

Summary and Conclusions  The HACS/pectin blend microparticles were prepared by spray-drying technique to obtain effective targeted drug release to the colon. The mean particle size of the micro-particles (plain and blend) that were prepared in the present study was between 5.8 and 7.3 μm. The microparticles were positively charged (ζ potential was in the range of 20.3 to 30.8), and the encapsulation efficiency was between 80.1% and 94.7%. The blending of HACS with pectin improved the encapsulation efficiency and decreased the drug dissolution in the gastric condition (pH 1.2) from the pectin-based microparticles. Results of the drug release study indicated that the colonic-controlled drug delivery could be obtained from spray-dried HACS/pectin blend microparticles, and the drug release mechanism was found to be by diffusion or erosion or a combination of both. Published: September 30, 2005.     

Gene delivery using biodegradable polyelectrolyte microcapsules prepared through the layer-by-layer technique

Biodegradable and non‐biodegradable microcapsules were prepared via the layer‐by‐layer (LbL) technique consisting of the polyelectrolyte pairs of dextran sulphate/poly‐L ‐arginine and poly(styrene sulfonate)/poly(allylamine hydrochloride), respectively, in an attempt to encapsulate plasmid DNA (pDNA) for efficient transfection into NIH 3T3 cells. Results indicated the retention of bioactivity in the encased pDNA, as well as a correlation between the level of in vitro gene expression and biodegradability properties of polyelectrolyte. Furthermore, the incorporation of iron oxide nanoparticles within the polyelectrolyte layers significantly improved the in vitro transfection efficiency of the microcapsules. As a novel pDNA delivery system, the reported biodegradable microcapsules provide useful insight into plasmid‐based vaccination and where there is a prerequisite to deliver genes into cells capable of phagocytosis. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 1088–1094, 2012