多糖凝胶骨架结肠定位给药缓释系统的体外释放研究

目的: 筛选多糖材料作为水凝胶骨架,以达到结肠定位释药目的.方法: 选用海藻酸钠、果胶、壳聚糖、瓜木耳胶与药物混和制粒,灌装肠溶或结肠溶胶囊,考察其在人工胃液,人工肠液及人工结肠液中的释放情况.结果: 难溶性药物的海藻酸钠骨架结肠溶胶囊在人工胃液和小肠液中均不释放,人工结肠液中3 h释药低于30%;果胶骨架肠溶胶囊在人工胃液亦不释药,人工肠液中5 h释药仅为15%.水溶性药物在人工肠液中5 h释放可达50%.结论: 难溶性药物的海藻酸钠/结肠溶胶囊和果胶/肠溶胶囊体外释放度结果符合结肠定位的要求,可以作为建立酶触发体外释放评价方法和体内评价的制剂形式.水溶性药物的果胶/肠溶胶囊是较理想的缓释剂型.     

酶控渗透泵型结肠定位微丸的制备及体外释放度考察

目的制备以果胶钙和醋酸纤维素为包衣材料,5-氨基水杨酸（5-ASA）为模型药物的酶触发渗透泵型结肠定位微丸,并考察其体外释药特征及释药机制。方法采用包衣锅法制备含药丸芯,选用L9（3）4正交实验设计,以体外释放度为评价指标优化包衣液处方及丸芯中渗透剂的用量,并进行体外释药模型拟合。结果制备5-ASA渗透泵酶触发微丸最佳工艺参数为：包衣增重25%;药物与NaCl（丸芯）比为3∶1;醋酸纤维素与果胶钙（包衣液）用量比为2∶3。所得微丸在人工胃液中2 h,人工小肠液中4 h累计释放率〈8%,人工结肠液12 h累计释放率〉70%,表明结肠定位性较为突出,且可以在结肠持续释放药物以维持局部药物浓度,进一步研究释药机理表明为零级释放。结论采用果胶钙与醋酸纤维素为包衣材料制备渗透泵酶触发结肠定位微丸可实现结肠定位作用。     

美沙拉嗪结肠靶向微丸的制备和体外评价

目的以结肠溶型丙烯酸树脂为包衣材料制备美沙拉嗪pH控制型结肠靶向微丸,评价其体外释药特性。方法挤出滚圆法制备美沙拉嗪微丸,采用L934正交设计实验优化工艺条件,流化床包衣机包衣,采用U884均匀设计试验优化工艺参数,考察了微丸圆整度、收率及体外释药特性。结果优化条件所得的微丸外观圆整,粒径分布均匀,收率高,在人工胃液中2h、人工小肠液中4h累计释放率<5%,人工结肠液1h累计释放率>95%,具有明显的结肠靶向释药特性。结论美沙拉嗪结肠靶向微丸具有良好的体外结肠靶向释药特性,可进一步进行体内释药行为考察。     

苦参碱壳聚糖微球的制备及体外释药

目的:以壳聚糖为囊材制备苦参碱结肠靶向给药微球及评价其体外释药情况。方法:用乳化化学交联法制备微球,以微球的粒径分布百分数、载药量及包封率为优化指标对影响微球制备的主要因素用正交试验设计优化制备条件;并对最佳制备工艺制得的微球进行3种不同递质(人工胃液、人工肠液及大鼠结肠液)中的体外释放度评价。结果:制得的苦参碱壳聚糖微球在电镜下,球形表面圆整,粒径分布适宜,微球平均粒径为(68.3±2.7)μm,平均载药量为(16.0±0.5)%,平均包封率为(66.3±4.2)%。苦参碱壳聚糖微球在人工胃液中2h不释药;在人工肠液中4h内释放不到1%,96h释药不到10%;在含大鼠结肠内容物的磷酸盐缓冲液(pH6.8)中4h释放10%左右,36h释药近50%,此后释药趋于缓慢,96h释药近80%。结论:苦参碱壳聚糖微球几乎不在上消化道释药,而是在结肠靶向释药。     

左氧氟沙星羧甲基壳聚糖微球结肠靶向释药的实验研究

目的:检测所制备的左氧氟沙星羧甲基壳聚糖(LVFX/CMC)微球在人工消化液中和大鼠体内结肠靶向释药的性能。方法:以分光光度仪测定微球在人工消化液中的累积释放量,电镜观察微球在人工消化液中形态的改变。SD大鼠60只,随机分为两组,分别以LVFX/CMC微球(含40 mg左氧氟沙星)及等量左氧氟沙星溶剂灌胃,以高效液相色谱法对LVFX/CMC微球和左氧氟沙星(LVFX)灌胃后大鼠盲肠、结肠中药物浓度进行定量检测。结果:左氧氟沙星壳聚糖微球在人工胃液介质中溶解缓慢,2 h仅释药8.62%;在人工小肠液介质中溶解速度稍见加快,6 h释药29.39%,但表现为药物缓释曲线,24 h仅释药42.13%;在人工结肠液中,4 h后释药84.56%,24 h内累积释药量为93%。扫描电镜观察人工胃液中的微球明显溶胀,稍见变形;人工结肠液中的微球溶解,粒径明显减小。灌胃后LVFX/CMC微球组5和9 h时段盲肠、结肠药量明显高于LVFX组。结论:左氧氟沙星羧甲基壳聚糖微球在体外、体内实验中的释放符合结肠靶向释药的特点。     

肠康宁结肠靶向胶囊体外释放度的评价

目的 对pH依赖型肠康宁结肠靶向胶囊体外释放性能进行评价,探讨制备中药结肠靶向制剂的可行性.方法 以木犀草素为评价指标,采用体外释放度测定法对该制剂的体外释放性能进行评价.结果 体外释放度试验结果表明,木犀草素在人工胃液2h后未见释放,在人工小肠液4h后未见释放,在人工结肠液1h后有一定的释放,2h后释放较高.结论 该制剂能在结肠定位释药.     

重组人粒细胞集落刺激因子壳聚糖胶囊的制备和体外释药特性

目的 :制备人重组粒细胞集落刺激因子 (rhG CSF)冻干粉剂壳聚糖胶囊 ,并对其体外释药性能进行评价。方法 :将rhG CSF冻干粉剂装入壳聚糖胶囊中 ,再以邻苯二甲酸羟丙基甲基纤维素 (HPMCP)包裹胶囊 ,用氮兰四唑蓝 (MTT)比色法测定其在人工胃液及小肠液中的体外释放性能。将荧光素钠 (FS)作为模型化合物在相同条件下进行实验 ,以激发波长 470nm、发射波长 5 13nm荧光检测FS壳聚糖胶囊在人工大肠液中的体外释放性能。用扫描电镜法评价壳聚糖胶囊在大肠内容物中的降解作用。结果 :在人工大肠液中壳聚糖具有明显降解作用。rhG CSF壳聚糖胶囊在人工胃液 (2h)和人工小肠液 (6h)内累积释药量为 (15 .5± 6 .5 ) % ,n =6。而在人工大肠液中 ,FS壳聚糖胶囊 4h释药基本完全。结论 :用HPMCP包膜的rhG CSF壳聚糖胶囊具有潜在的结肠靶向释药特性。     

氢化可的松结肠靶向片包衣处方筛选及其释放机制研究

目的:筛选氢化可的松结肠靶向片的包衣处方,并考察其释放机制。方法:采用星点设计-效应面法优化氢化可的松结肠靶向片的包衣处方。以明胶-壳聚糖包衣(GC)层和聚丙烯酸树脂Eudragit L100包衣(E)层的包衣增质量为自变量,以靶向片在人工胃液、人工小肠液及人工结肠液的累积释放度(Q2 h、Q4 h、Q24 h)为因变量,分别进行多元线性和非线性拟合。根据绘制效应面选取最佳处方,并通过数学原理和相关模型探讨其释放机制。结果:GC层及E层包衣增质量最佳值分别为4%和20%;制备的3批氢化可的松结肠靶向片的平均Q2 h、Q4 h、Q24 h分别为0.16%、4.7%、93.35%;其释放符合一级动力学模型(r=0.984 5)。结论:根据筛选的包衣处方制备的氢化可的松结肠靶向片的体外释放符合缓释制剂要求。     

吲哚美辛结肠靶向胶囊的制备及体外释药评价

目的 开发一种结肠靶向胶囊,使吲哚美辛达到结肠部位实现靶向释放。方法 以蘸胶工艺制备不溶性半透膜囊体,灌装药物后以果胶片封住囊体,外套上普通胶囊壳后外包肠溶衣,进行体外释放试验。结果 该给药系统在人工胃液中不变形,药物不释放,采用PEG-2 000∶CA为60%的不溶性囊体,包衣增重90%,药物∶NaCl为1∶1制备的胶囊,药物在人工肠液中3 h释放<10%,在人工结肠液中10 h药物释放超过70%,基本释放完全,达到结肠定位释放要求。结论 吲哚美辛结肠靶向胶囊能实现在结肠定位释放药物。     

甲硝唑结肠定位肠溶片的制备及质量控制

目的:研制甲硝唑结肠定位肠溶片的制备工艺和处方,考察其体外释放度并制定该剂型的质量评价标准.方法:模拟服药后该剂型在胃肠道中的生理释药过程,用3种不同pH值的磷酸盐缓冲液作为释放介质,分别在其最大吸收波长277,321和317nm处检测甲硝唑的吸收度,并根据特定时间的药物吸收计算出累计释放度.结果:药片在人工胃液、pH 6.8人工肠液不释药;在pH 7.8人工结肠液中2～20μg穖L-1范围内线性良好,平均回收率104.8%,RSD为0.98%.结论:甲硝唑结肠定位肠溶片的体外释放度检测结果合格.     

Development and Evaluation of Microbial Degradation Dependent Compression Coated Secnidazole Tablets for Colonic Delivery

The present paper describes development of a polysaccharide based compression coated tablets of secnidazole for colon delivery. Core tablet containing secnidazole was compression coated with various proportions of guar gum, xanthan gum and chitosan, either alone or in combinations. Drug release studies were performed in simulated gastric fluid (SGF) for 2 h followed by simulated intestinal fluid (SIF, pH 7.4) up to 24 h. Secnidazole release from the prepared formulations was dependent on the type and concentration of polymer used in the formulation. Tablets coating containing either guar gum or xanthan gum showed ~30-40% drug release in 8 h. Further, in vitro dissolution studies of selected formulations performed in the dissolution media with rat caecal contents showed 54.48±0.24 - 60.42±0.16% of drug release. Formulations with single polymer in coating layer were unsuitable for targeting secnidazole release to colon region. Combination of chitosan with guar gum or xanthan gum exhibited control over secnidazole release.     

Development and characterization of colon specific drug delivery system bearing 5-ASA and camylofine dihydrochloride for the treatment of ulcerative colitis

The treatment of ulcerative colitis (inflammatory bowel disease, IBD) has been achieved by using colon specific drug delivery system bearing 5-ASA and Camylofine dihydrochloride. Chitosan microspheres were prepared separately for both the drugs using emulsion method followed by enteric coating with Eudragit^®S-100. The in vitro drug release was investigated in different simulated GIT medium. The drug release in PBS (pH7.4) and simulated gastric fluid has shown almost similar pattern and rate, whereas a significant increase in drug release (70.3?±?1.36 and 72.5?±?1.33% of 5-ASA and Camylofine, respectively) was observed in medium containing 3% rat caecal matter, after 24?h. In control study, 57.1?±?1.13% of 5-ASA and 59.2?±?1.2% of Camylofine release was observed in 24?h. For enzyme induction, rats were orally administered with 1?mL of 1% w/v dispersion of chitosan for 5 days and release rate studies were conducted in SCF with 3% w/v of caecal matter. An enhanced drug release (i.e., 92.3?±?3.81 and 95.5?±?3.52% 5-ASA and Camylofine, respectively) was observed after 24?h in dissolution medium containing 3% caecal content obtained from enzyme induced animals. In vivo data showed that microspheres delivered most of its drug load (76.55?±?2.13%) to the colon after 9?h, which reflects its targeting potential to the colon. It is concluded that orally administered microspheres of both drugs can be used together for the specific delivery of drug to the colon and reduce symptoms of ulcerative colitis.     

Design,development and optimization of oral colon targeted drug delivery system of azathioprine using biodegradable polymers

The present study was aimed at designing a microflora triggered colon targeted drug delivery system (MCDDS) based on swellable polysaccharide, Sterculia gum in combination with biodegradable polymers with a view to specifically deliver azathioprine in the colonic region for the treatment of IBD with reduced systemic toxicity. The microflora degradation properties of Sterculia gum was investigated in rat caecal phosphate buffer medium. The polysaccharide tablet cores were coated to different film thicknesses with blends of Eudragit RLPO and chitosan and overcoated with Eudragit L00 to provide acid and intestinal resistance. Swelling and drug release studies were carried out in simulated gastric fluid, SGF (pH 1.2), simulated intestinal fluid, SIF (pH 6.8) and simulated colonic fluid, SCF (pH 7.4 under anaerobic environment), respectively. Drug release study in SCF revealed that swelling force of the Sterculia gum could concurrently drive the drug out of the polysaccharide core due to the rupture of the chitosan/Eudargit coating in microflora activated environment. The degradation of chitosan was the rate-limiting factor for drug release in the colon. Drug release from the MCDDS was directly proportional to the concentration of the pore former (chitosan), but inversely related to the Eudragit RLPO coating thickness.     

Development and characterization of polymer-coated liposomes for vaginal delivery of sildenafil citrate

Vaginal administration of sildenafil citrate has shown recently to develop efficiently the uterine lining with subsequent successful embryo implantation following in vitro fertilization. The aim of the present study was to develop sildenafil-loaded liposomes coated with bioadhesive polymers for enhanced vaginal retention and improved drug permeation. Three liposomal formulae were prepared by thin-film method using different phospholipid:cholesterol ratios. The optimal liposomal formulation was coated with bioadhesive polymers (chitosan and HPMC). A marked increase in liposomal size and zeta potential was observed for all coated liposomal formulations. HPMC-coated liposomes showed the greater bioadhesion and higher entrapment efficiency than chitosan-coated formulae. The in vitro release studies showed prolonged release of sildenafil from coated liposomes as compared to uncoated liposomes and sildenafil solution. Ex vivo permeation study revealed the enhanced permeation of coated relative to uncoated liposomes. Chitosan-coated formula demonstrated highest drug permeation and was thus selected for further investigations. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) confirmed the successful coating of the liposomes by chitosan. Histopathological in vivo testing proved the efficacy of chitosan-coated liposomes to improve blood flow to the vaginal endometrium and to increase endometrial thickness. Chitosan-coated liposomes can be considered as potential novel drug delivery system intended for the vaginal administration of sildenafil, which would prolong system's retention at the vaginal site and enhance the permeation of sildenafil to uterine blood circulation.     

硝苯地平胃漂浮型延迟缓释微丸的制备

目的:制备硝苯地平胃漂浮型延迟缓释微丸并考察其体外漂浮行为.方法:挤出滚圆法制备漂浮型空白丸芯,空白丸芯上药法制备载药丸芯,分别以Surelease水分散体和Eudragit L30D-55为包衣材料,进行流化床包衣.采用正交试验设计对处方进行优化.结果:模拟人体胃肠道条件下溶出,自制漂浮型微丸在人工胃液中6 h累计释放小于10%,换人工肠液后12 h释放完全,体外漂浮10 h以上. 结论:自制微丸达到了漂浮和延迟缓释的效果.     

Development and Evaluation of pH-Dependent Micro Beads for Colon Targeting

The purpose of this research was to develop and evaluate multiparticulates of alginate and chitosan hydrogel beads exploiting pH sensitive property for colon-targeted delivery of theophylline. Alginate and chitosan beads were prepared by ionotropic gelation method followed by enteric coating with Eudragit S100. All formulations were evaluated for particle size, encapsulation efficiency, swellability and in vitro drug release.In vitro dissolution studies performed following pH progression method demonstrated that the drug release from coated beads depends on coat weights applied and pH of dissolution media. Mechanism of drug release was found to be swelling and erosion-dependent. The studies showed that formulated alginate and chitosan beads can be used effectively for the delivery of drug to colon and a coat weight of 20% weight gain was sufficient to impart an excellent gastro resistant property to the beads for effective release of drug at higher pH values.     

Mucoadhesive and floating chitosan-coated alginate beads for the controlled gastric release of amoxicillin

This work focused on the development of mucoadhesive and floating chitosan-coated alginate beads as a gastroretensive delivery vehicle for amoxicillin, towards the effective eradication of Helicobacter pylori, a major causative agent of peptic ulcers. Alginate was used as the core bead core polymer and chitosan as the mucoadhesive polymer coating. Amoxicillin-loaded alginate beads coated with 0.5% (w/v) chitosan (ALG/0.5%CHI) exhibited excellent floating ability, high encapsulation efficiency, high drug loading capacity, and a strong in vitro mucoadhesion to the gastric mucosal layer. In vitro, amoxicillin was released faster in simulated gastric fluid (pH 1.2, HCl) than in simulated intestinal fluid (phosphate buffer, pH 7.4). ALG/0.5%CHI could be prepared with a > 90% drug encapsulation efficiency and exhibited more than 90% muco-adhesiveness, 100% floating ability, and achieved sustained release of amoxicillin for over six hours in SGF.     

Muco-adhesive multivesicular liposomes as an effective carrier for transmucosal insulin delivery

Considering limitations of conventional insulin therapies, the present study characterizes usefulness of novel mucoadhesive multivesicular liposomes as a mucoadhesive sustained release carrier of insulin via nasal and ocular routes, thus attempts to develop non-invasive carrier system for the controlled release of bioactives. Multivesicular liposomes (MVLs) of 26–34 μm were prepared with a high protein loading (58–62%) and were coated with chitosan and carbopol. These mucoadhesive carriers were characterized by zeta potential studies, in vitro mucoadhesion test and insulin protective ability against nasal aminopeptidase. In vitro, mucoadhesive carriers released insulin for a period of 7–9 days compared to 24 h of conventional liposomes. After intranasal administration to STZ induced diabetic rats, the mucoadhesive MVLs (chitosan coated MVLs) effectively reduced plasma glucose level up to 2 days (35% reduction), compared to non-coated MVLs (32% at 12 h) and conventional liposomes (34% at 8 h). Although the differences are statistically insignificant, chitosan coated formulation has shown a better hypoglycemic profile as the effects were prolonged compared to carbopol coated formulation. When compared to ocular route, chitosan formulation after nasal administration has shown better therapeutic profile as the hypoglycemic effects were prolonged until 72 h. The effectiveness of this chitosan coated MVLs was further demonstrated by the significant quantities of ELISA detectable insulin levels after nasal (334.6 μIu/ml) and ocular (186.3 μIu/ml) administration. These results demonstrate that mucoadhesive carrier is a viable option for a sustained release transmucosal insulin carrier, and open an avenue to develop a non-invasive carrier platform for the controlled release of bioactives.     

Design,development and in vitro-in vivo study of a colon-specific fast disintegrating tablet

Objective: Targeted delivery systems for the treatment of Inflammatory bowel disease (IBD) are designed to increase local tissue concentrations of anti-inflammatory drugs from lower doses compared with systemic administration. The objective of this study was to formulate and evaluate an oral system designed to achieve site-specific and instant drug release in the colon for effective treatment of IBD.

Materials and methods: The system consists of a core tablet containing the model drug diclofenac sodium, superdisintegrant sodium starch glycolate, and coated with enteric polymer Eudragit FS 30 D to achieve different total percentage weight gain. Drug release studies were carried out using a changing pH method. A placebo formulation containing barium sulphate in the tablet was administered to human volunteers for in vivo X-ray studies. SEM studies were performed to determine coating thickness and film topography.

Results: In vitro studies revealed that the tablet with 10% coating level released the drug after 5?h lag time corresponding to the colonic region. Tablets with 10% coating level could maintain their integrity in human volunteers for 5?h, approximating colon arrival time and release the drug instantaneously.

Discussion: Colon-targeting and instant drug release for 10% coating level was due to the dissolution of the Eudragit FS 30 D and the immediate release effect of superdisintegrant. It was observed that as the coating level increased, the lag time also increased. This was because of increased diffusion path length and tortuosity at higher coating levels.

Conclusion: An in vivo-in vitro study revealed that not only the sensitivity of the polymer to the pH environment but also the thickness of coating plays an important role in colon delivery and the tablet with 5% superdisintegrant and 10% coating level achieved the desired performance of the colon targeting.     

Eudragit-coated dextran microspheres of 5-fluorouracil for site-specific delivery to colon

Objective of the present investigation was to prepare and evaluate the potential of enteric coated dextran microspheres for colon targeting of 5-fluorouracil (5-FU). Dextran microspheres were prepared by emulsification-crosslinking method and the formulation variables studied included different molecular weights of dextran, drug:polymer ratio, volume of crosslinking agent, stirring speed and time. Enteric coating (Eudragit S-100) of dextran microspheres was performed by oil-in-oil solvent evaporation method using different coat:core ratios (4:1 or 8:1). Uncoated and coated dextran microspheres were characterized by particle size, surface morphology, entrapment efficiency, DSC, in vitro drug release in the presence of dextranase and 2% rat cecal contents. The release study of 5-FU from coated dextran microspheres was pH dependent. No release was observed at acidic pH; however, the drug was released quickly where Eudragit starts solublizing there was continuous release of drug from the microspheres. Organ distribution study was suggested that coated dextran microspheres retard the release of drug in gastric and intestinal pH environment and released of drug from microspheres in colon due to the degradation of dextran by colonic enzymes.