4-氨基水杨酸钠结肠定位包衣片的制备与体外释放

目的:制备pH依赖和时间双重控制的4-氨基水杨酸钠结肠定位给药系统,并考察其体外释药行为。方法:以渗透型丙烯酸树脂EudragitRL与EudragitRS混和包衣液作为内层缓释层,pH依赖型丙烯酸树脂EudragitFS作为外层肠溶层,以柠檬酸三乙酯作为增塑剂,使用可调速糖衣机包衣,并研究包衣片在模拟人体胃肠道环境中的释放情况。结果:系统在0.1mol·L--1盐酸中2h无药物释放,在pH6.5的磷酸盐缓冲液中12h几乎无药物释放,在pH7.0和pH7.4时呈缓慢释放,且pH越高,释药时滞越短,肠溶层厚度的增加可延长释药时滞,12h内释药完全。结论:用渗透型丙烯酸树脂EudragitRL与EudragitRS的混合液作为缓释层,用pH依赖型丙烯酸树脂EudragitFS作为肠溶层可制备4-氨基水杨酸钠结肠定位包衣片。     

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。     

5—氨基水杨酸结肠定位释药包衣片的研制

目的：构建口服5－氨基水杨酸结肠定位释药系统。方法：以延时性和pH值依赖性为结肠控释依据,采用多层薄膜包衣法制备结肠定位释放片剂,采用γ射线显影法,考察包衣片在狗体内的释药部位与释药时间。结果：研制的口服5－氨基水杨酸结肠定位释药片剂制备工艺简单,药物释放稳定,在狗的升结肠崩解释药。结论：构建的5－氨基水杨酸的口服结肠定位释药系统具有进一步开发应用前景。     

4-氨基水杨酸钠结肠定位包衣片的制备及释放度测定

目的:以多层包衣法制备4-氨基水杨酸钠口服结肠定位系统,并考察其释放度,评价包衣工艺的稳定性。方法:用渗透型和肠溶型丙烯酸树脂依次包衣,制备pH、时间双重依赖的4-氨基水杨酸钠口服结肠定位包衣片;采用紫外分光光度法测定包衣片在不同pH条件下的释放度及3批包衣片在pH=7.4介质中的累积释放度,计算并比较释放参数T50、Td、T80、m。结果:包衣片在pH=6.5介质中12h释药量小于5%,有明显时滞;在pH=7.0、pH=7.4介质中12h内释药量均大于80%,无时滞效应;3批包衣片溶出度参数之间比较均无显著性差异(P>0.05)。结论:以渗透型和肠溶型丙烯酸树脂依次包衣制备的4-氨基水杨酸钠口服结肠定位包衣片具备理想的定位与缓释功能,包衣工艺稳定,重现性好。     

星点设计-效应面法优化盐酸青藤碱结肠定位片处方

目的应用星点设计-效应面法优化盐酸青藤碱结肠定位片的处方。方法以肠溶层包衣增质量分数、尤特奇S100和L100质量比为考察因素,以药物在第6、8、12 h累积释放度的综合评分值Y作为评价指标,运用Statistica 6.0软件对实验数据进行多元线性拟合和二项式拟合,对比拟合结果得出最佳数学模型,绘制三维效应面图和等高线图,优选最佳处方并验证。结果二项式拟合方程相关系数(r=0.994 7)优于多元线性拟合方程的相关系数(r=0.168 5),所以最终选择二项式拟合为最佳数学模型,优选的最佳处方为肠溶层包衣增质量分数为4.5%,S100和L100的质量比为3∶1,对优选处方进行验证结果均符合结肠定位释药要求。结论星点设计-效应面法简单可靠,所建立的数学模型具有良好的预测性,可以用来优化盐酸青藤碱结肠定位片的处方。     

美沙拉嗪两种时间依赖型结肠定位释药系统的研究

目的考察两种美沙拉嗪时间依赖型结肠定位释药片(time-dependent colon specific tablets,TDCT)体外释放性质,以期为不同程度炎症性肠病治疗提供相应的制剂。方法以羟丙基纤维素和微晶纤维素为包衣材料,采用压制包衣法,制备压制包衣TDCT。有机酸诱导型TDCT采用湿法制粒制备含有机酸片芯,片芯外依次包隔离层和Eudragit RS30D时滞层,通过片芯有机酸与Eudragit RS30D发生离子交换,增大膜的通透性制备延迟缓释片。考察药物释放的影响因素。结果两种美沙拉嗪TDCT具有稳定的结肠释药特性,且压制包衣TDCT有突释性,有机酸诱导型TDCT具有缓释特性。结论可以根据结肠定位释药的要求,选择不同释药类型的TDCT。     

氢溴酸高乌甲素脉冲释放片的研究*

目的以氢溴酸高乌甲素为模型药物研究脉冲释放片剂并同时考察用包衣的方法制备脉冲给药系统的可行性.方法以氢溴酸高乌甲素为模型药物,制备适宜的片芯;以乙基纤维素和丙烯酸树脂Ⅱ号的乙醇溶液包衣,采用滚转包衣法,制备氢溴酸高乌甲素脉冲释放片剂.通过体外释放度实验,考察片芯和衣层对片剂释药行为的影响.结果片芯处方、包衣层厚度及包衣处方对氢溴酸高乌甲素脉冲释放片的释药行为均有影响.结论通过调整片芯中崩解剂的用量、包衣层的厚度和组成,可以得到具有不同释药时滞的氢溴酸高乌甲素片剂.     

防潮型包衣材料Opadry AMB包复阿司匹林片研究

用特殊防潮性包衣材料--OpadryAMB对阿司匹林片进行包衣,考察素片和薄膜包衣片中阿司匹林的含量、溶出度、稳定性等.结果表明阿司匹林包复Opadry薄膜衣后增加了稳定性,OpadryAMB防潮效果明显.     

替硝唑结肠给药系统的研制

依据时控型结肠给药系统原理，以替硝唑为模型药物．利用于压包衣和薄膜包衣双层包衣的方法制备了结肠给药系统，并对影响药物释放的因素(如EC粒度，HPMC粘度，时控层厚度，片刑硬度等)、肠衣层性能和药物释放稳定性等进行了考查。结果表明，HPMC粘度增加使药物释放滞后时间延长,但高粘度HPMC会导致药物释放无明显突跃点；包芯片硬度40～60N、片重0．26～0．28g的片剂药物释放较稳定。加速试验(3个月)结果表明,药物释放稳定性良好。     

5-氨基水杨酸结肠定位释药包衣片在狗体内的靶向性研究

目的 考察自制的口服5-氨基水杨酸结肠定位释药包衣片在体内的结肠靶向性。方法 用γ射线显影法考察结肠定位释放包衣片在狗体内的释药部位与释药时间。结果 5-氨基水杨酸结肠定位释药片剂在狗的升结肠崩解释药。结论 5-氨基水杨酸结肠定位释药片具有结肠靶向性。     

Exploiting gastrointestinal bacteria to target drugs to the colon: an in vitro study using amylose coated tablets

The bacterial substrate amorphous amylose, in the form of a film coating, provides a means of delivering drugs to the colon. This coating has traditionally been applied to multi-unit systems, in part because of the small size and divided nature of this type of dosage form, which provides a large surface area for enzymatic attack and drug release. The present study was conducted to explore the utility of the coating for colonic targeting of single unit tablet systems. Amylose was combined with the water-insoluble polymer ethylcellulose, which acts as a structuring agent, in different proportions to produce film coatings of various thicknesses for application to mesalazine (mesalamine or 5-aminosalicylic acid)-containing tablets. Drug release from the coated products was assessed under pH dissolution conditions resembling the stomach and small intestine, and also in conditions simulating the colon using a batch culture fermenter inoculated with human faecal bacteria. The rate and extent of drug release was related to the ratio of amylose to ethylcellulose in the film and the thickness of the coating. Increasing the proportion of ethylcellulose in the film and/or the thickness of the coating depressed the rate of drug release in the conditions of the upper gastrointestinal tract. Drug release from the coated products was accelerated in the fermentation environment of the colon. This is attributed to bacterial digestion of the amylose component of the film coat producing pores for drug diffusion. This work indicates that amylose coated tablet formulations are promising vehicles for drug delivery to the colon.     

Formulation, evaluation and pharmacokinetics of colon targeted pulsatile system of flurbiprofen

Objective: The intent of the present investigation is to develop colon targeted compression coated flurbiprofen pulsatile release tablets that retard the drug release in the upper gastro intestinal system but progressively release in the colon. Materials and methods: Flurbiprofen core tablets were prepared by direct compression method and were compression coated with hydroxypropyl methylcellulose and Eudragit S100. The formulation is optimized based on the in vitro drug release study and further evaluated by X-ray imaging and pharmacokinetic studies in healthy humans for colonic delivery. Results and discussions: The optimized formulation showed negligible drug release (7.26?±?0.05%) in the initial lag period followed by progressive release (99.27?±?0.46%) for 24?h. The X-ray imaging study in human volunteers showed that the tablets reached the colon without disintegrating in the upper gastrointestinal tract. The C(max) of colon targeted tablets was 10792.62?ng/mL at T(max) 10?h where as in case of immediate release tablets the C(max) was 15684.79?ng/mL at T(max) 3?h signifies the ability of compression coated tablets to target the colon. Conclusion: Development of pulsatile release compression coated tablets using combination of time dependent and pH sensitive approaches was suitable to target the flurbiprofen to colon.     

Development of sustained release fast-disintegrating tablets using various polymer-coated ion-exchange resin complexes

Complex formation between drugs and ion-exchange resins was investigated and the effects of coating by various aqueous polymeric dispersions on the complexes were evaluated for developing new sustained-release fast-disintegrating tablets (FDTs). Complexes of ion-exchange resin and dextromethorphan, a model drug, were prepared using different particle sizes of the resins. Aqueous colloidal dispersions of ethylcellulose (EC) and poly(vinyl acetate) (Kollicoat SR30D) were used for fluid-bed coating. Based on drug loading, release profiles, and scanning electron microscopy (SEM) images, the coated particles were granulated with suitable tablet excipients and then compressed into the tablets. Drug release profiles and SEM pictures were compared before and after the manufacturing processes. As the particle size of resins increased, the drug loading and release rate decreased due to the reduced effective diffusion coefficient and surface area. Higher coating level decreased the release rate further. In contrast to EC, Kollicoat SR30D coated particles could be compressed into tablets without any rupture or cracks on the coating since the mechanical properties of the polymer was more resistant to the manufacturing processes. This resulted in no significant changes in release rates. SEM showed the mechanical strength of the polymers affected the morphological change after compression. When the drug release profiles were applied into Boyd model and Higuchi equation, the linear relationship was observed, indicating that the diffusion within the resin matrix is the rate-controlling step.     

Composite film-coated tablets intended for colon-specific delivery of 5-aminosalicylic acid: using deesterified pectin

Combinations of Eudragit RS and deesterified pectin, polygalacturonic acid (PGA), or its potassium and sodium salts, when applied as a film coat, has a potential value as a colon-specific delivery system. Dispersions of PGA in Eudragit RS were used as the film former for coating of 5-aminosalicylic acid (5-ASA) tablet cores. Drug release behavior was assessed, in vitro, under simulating conditions in term of pH and time to in vivo during their transit to the colon. Negligible drug release occurred during first 5 hr where the coated tablets were in the stomach and small intestine. After that, the pectinolytic enzymes were added into the pH 6.8 medium to simulate the in vivo condition where there is the digestion of bacteria in the colon. The release of 5-ASA from the coated tablets occurred linearly as a function of time. Drug release depended on the composition of the mixed film, as well as the ratio of Eudragit RS to PGA or its salts. The highest drug release from the coated tablets of about 40% was obtained when the ratio of Eudragit RS to potassium salt of PGA was 2.5 to 1. Drug release profiles seemed to conform to the mechanism involving the osmotically driven release and formation of channels in the film caused by dissolution of PGA salts. Channel formation was, in most cases, activated by the presence of pectinolytic enzymes, showing that the PGA in the mixed film was subjected to enzymic breakdown. In conclusion, PGA could be used as an additive in Eudragit RS films to control the release of colonic delivery system.     

Silk fibroin as a novel coating material for controlled release of theophylline

The aim of this study was to explore potential use of the silk fibroin (SF) as an aqueous coating material for theophylline tablets. We have examined the film forming and coating properties of heat-treated fibroin, SF solution having different amounts of polyethylene glycol (PEG) and 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide (EDC) cross-linked SF. Heat-treated SF material possessed a brittle structure, which resulted in poor film forming and coating properties. The optimum PEG amount in SF solution was determined as 17% (by weight) for an acceptable film forming and zero order release profile. EDC cross-linked SF has shown a very good film forming and coating property with a potential for sustaining the drug release from coated theophylline tablets. Dissolution data for coated theophylline tablets were analyzed using Ritger and Peppas equation to describe the mechanism of drug release. Drug release from the EDC coated tablets followed zero-order kinetics. Release rate constants were found to be 0.26, 0.19, 0.16% min⁻¹ for single-coated, double coated, and triple coated tablets, respectively. These results clearly demonstrated that silk fibroin has high utility as a novel aqueous coating material for controlled release products.     

吲哚美辛肠溶滴丸的研制及其体外释药研究

研制吲哚关辛（IDM）肠溶滴丸,并考察其体外释药特性。方法：选用PEG6000为基质,用正交试验筛选IDM滴丸的最佳处方及工艺,并采用聚丙烯酸树脂Ⅱ为肠溶材料对其进行包衣,制备IDM肠溶滴丸。转篮法对其体外释药特性进行考察,并与市售IDM肠溶片进行比较。结果：筛选出IDM滴丸最佳制备条件为：IDM与总基质的质量比为1：3,滴速为65滴／min,滴制温度为90℃,冷凝液温度为5℃。IDM肠溶滴丸及市售IDM肠溶片在酸性介质中几乎不释药,而在pH为6.8的磷酸盐缓冲液中,IDM肠溶滴丸的释药速度显著高于市售肠溶片（P〈0．05）。结论：IDM肠溶滴丸具有明显肠溶效果,同时可加快IDM在肠道中的释放速度,值得进一步研究。     

Development of Pulsatile Systems for Targeted Drug Delivery of Celecoxib for Prophylaxis of Colorectal Cancer

The aim of the present study was to formulate fast release enteric-coated tablets for drug delivery to the colon. Two different approaches were used for the preparation of these tablets. The first included making use of superdisintegrant (SD) in the tablet. The amount of super disintegrant (cross-linked PVP) in the tablet and the coat weight were varied to formulate a suitable time-controlled release system, that would provide colon-specific drug delivery. The second approach consisted of development of osmogen-based tablets for drug delivery into the tracts of the colon. Two different osmogens, sodium chloride and potassium chloride, were used. These also were coated at different coat levels. Celecoxib was used as a model drug. In vitro drug release studies showed that superdisintegrants were more effective in showing burst effect in the tablets and therefore showed a rapid drug release as compared with osmogens, which would show a sustained drug release all through the colon. Osmotic tablets were formulated making use of a high concentration of osmogen sodium chloride (OM-SC) and potassium chloride (OM-KC) were further enteric-coated. These also were found to be useful in providing a sustained delivery of nearly 80–90% of the drug into the colonic region. The coat weight required in these tablets for protection in the upper gastrointestinal conditions varied from 9.69% in OM-KC tablets to 4.65% in OM-SC tablets.     

Development of pulsatile systems for targeted drug delivery of celecoxib for prophylaxis of colorectal cancer

The aim of the present study was to formulate fast release enteric-coated tablets for drug delivery to the colon. Two different approaches were used for the preparation of these tablets. The first included making use of superdisintegrant (SD) in the tablet. The amount of super disintegrant (cross-linked PVP) in the tablet and the coat weight were varied to formulate a suitable time-controlled release system, that would provide colon-specific drug delivery. The second approach consisted of development of osmogen-based tablets for drug delivery into the tracts of the colon. Two different osmogens, sodium chloride and potassium chloride, were used. These also were coated at different coat levels. Celecoxib was used as a model drug. In vitro drug release studies showed that superdisintegrants were more effective in showing burst effect in the tablets and therefore showed a rapid drug release as compared with osmogens, which would show a sustained drug release all through the colon. Osmotic tablets were formulated making use of a high concentration of osmogen sodium chloride (OM-SC) and potassium chloride (OM-KC) were further enteric-coated. These also were found to be useful in providing a sustained delivery of nearly 80-90% of the drug into the colonic region. The coat weight required in these tablets for protection in the upper gastrointestinal conditions varied from 9.69% in OM-KC tablets to 4.65% in OM-SC tablets.     

Design,optimization and evaluation of mesalamine matrix tablet for colon drug delivery system

The aim of the present investigation was to develop and evaluate matrix tablet of mesalamine for colonic delivery by using Eudragit RSPO, RLPO and combination of both. The tablets were further coated with different concentration of pH-dependent methacrylic acid copolymers (Eudragit S100), by dip immerse method. The physicochemical parameters of all the formulations were found to be in compliance with the pharmacopoeial standards. The in vitro drug release study was conducted using sequential dissolution technique at pH 1.2 (0.1N) HCl, phosphate buffers pH 6.8 and 7.4, with or without rat cecal content mimicking different regions of gastro intestinal tract. The result demonstrated that the tablet containing Eudragit RLPO coated with Eudragit S100 (1 %) showed a release of 94.91 % for 24 h whereas in the presence of rat cecal content the drug release increases to about 98.55 % for 24 h. The uncoated tablets released the drug within 6 h. The in vitro release of selected formulation was compared with marketed formulation (Octasa MR). In vitro dissolution kinetics followed the Higuchi model via non-Fickian diffusion controlled release mechanism. The stability studies of tablets showed less degradation during accelerated and room temperature storage conditions. The enteric coated Eudragit S100 coated matrix of mesalamine showing promising site specific drug delivery in the colon region.     

Formulation,evaluation and pharmacokinetics of colon targeted pulsatile system of flurbiprofen

Objective: The intent of the present investigation is to develop colon targeted compression coated flurbiprofen pulsatile release tablets that retard the drug release in the upper gastro intestinal system but progressively release in the colon.

Materials and methods: Flurbiprofen core tablets were prepared by direct compression method and were compression coated with hydroxypropyl methylcellulose and Eudragit S100. The formulation is optimized based on the in vitro drug release study and further evaluated by X-ray imaging and pharmacokinetic studies in healthy humans for colonic delivery.

Results and discussions: The optimized formulation showed negligible drug release (7.26?±?0.05%) in the initial lag period followed by progressive release (99.27?±?0.46%) for 24?h. The X-ray imaging study in human volunteers showed that the tablets reached the colon without disintegrating in the upper gastrointestinal tract. The C_max of colon targeted tablets was 10792.62?ng/mL at T_max 10?h where as in case of immediate release tablets the C_max was 15684.79?ng/mL at T_max 3?h signifies the ability of compression coated tablets to target the colon.

Conclusion: Development of pulsatile release compression coated tablets using combination of time dependent and pH sensitive approaches was suitable to target the flurbiprofen to colon.