胃内滞留制剂的研究进展

延长制剂在胃内的滞留时间可以增加药物在胃部的吸收，从而降低全身毒副作用，提高生物利用度。依据药物制剂在体内的大小、比重及作用机制分为漂浮型胃内滞留系统、生物粘附型胃内滞留系统、漂浮与生物粘附协同型胃内滞留系统、高密度型胃内滞留系统和阻塞型胃内滞留系统等。本文就胃内滞留制剂研究的新进展作一综述。     

辅料对胃漂浮制剂漂浮性能的影响

胃漂浮制剂，是根据流体动力学平衡体系（HBS）原理设计，口服后长时间在胃内保持漂浮状态，能有效提高药物生物利用度的一种口服缓释制剂。随着药用辅料的发展和制剂技术的改进，胃漂浮制剂的剂型愈加丰富，有片剂、胶囊、微囊、微球、小丸等。胃漂浮制剂设计的关键是：其在胃内是否能达到预期的漂浮时间。通常胃漂浮制剂，     

胃内滞留漂浮型给药系统的研究概况与进展

讨论了胃内漂浮给药系统的研究概况与最新进展。这类制剂的关键在于其在胃内的漂浮性能，影响因素包括：材料、制备工艺、制剂的物理特性、持浮力、生理因素等。体外用浮力计测定浮力来预测体内漂浮性能，体内用闪烁照相法观察漂浮制剂的动态变化过程。尽管对胃漂浮制剂的体内漂浮性能存在很大争议，但其相对于普通控、缓释制剂的优越性却不容忽视，随着研究的深入，胃漂浮制剂将会有很大的发展。     

胃内滞留漂浮型缓释片的研究概况

目的:阐述胃内滞留漂浮缓释片的研究概况。方法:结合文献和资料,简述胃内滞留片的释药原理, 影响漂浮性能的因素以及漂浮性能控制。结果与结论:胃内漂浮制剂可以显著延长胃内滞留时间,并能提高生物利用度。已经引起了国内外学者越来越多的关注,成为药剂学研究的热点之一。     

胃内滞留漂浮型给药系统的研究概况与进展

讨论了胃内漂浮给药系统的研究概况与最新进展。这类制剂的关键 在于其在胃内的漂浮性能，影响因素包括：材料、制备工艺、制剂的物理特性、持浮力、重量因素等。体外用浮力计测定浮力来预测体内漂浮性能，体内用闪烁照相法观察漂浮制剂的动态变化过程。尽管对胃漂浮制剂的体内漂浮性能存在很大争议。但其相对于普通控、缓释制剂的优越性却不容忽视，随着研究的深入，胃漂浮制剂将会有很大的发展。     

胃内滞留漂浮型缓释制剂技术研究进展及其在中药制剂中的应用

胃内滞留漂浮型缓释制剂是根据流体动力学平衡控制系统(The Hydronamically Balanced Controlled Drug Delivery System,HBS)原理设计制备,口服后可以漂浮于胃液之上持续释放药物的一种特殊制剂.这种制剂由于自身密度小于胃内容物密度,通常在胃液中呈漂浮状态滞留5～6 h,达到延长药物在胃内的释放时间,改善药物吸收,提高生物利用度的目的.     

双嘧达莫胃内漂浮片的研制

双嘧达莫 ( dipyridamole,1 )可抑制血小板聚集 ,有抗血栓形成作用 ,临床上多用于血栓栓塞性疾病 ,也可用于缺血性心脏病。 1生物半衰期短 ,血浆t1/ 2 仅为 2～ 3h,每天需用药 3～ 4次 [1,2 ] ,加上此类患者一般需长期服药 ,故宜制成缓释制剂。考虑到 1主要在胃内吸收 ,若将其制成胃内漂浮片 ,延长其在胃内的停留时间 ,可达到使血药浓度波动性减小、降低毒副作用以及便于患者使用的目的。1　试药与仪器聚丙烯酸树脂 (批号 2 0 0 110 6 2 8- 2 )、聚丙烯酸树脂 (批号 2 0 0 0 32 71)均由连云港云升实业公司提供 ;羟丙甲纤维素 (HPMC,湖州…     

漂浮-生物黏附协同作用制剂的研究进展

目的介绍漂浮-生物黏附协同作用制剂研究进展。方法对漂浮-生物黏附协同作用制剂的作用特点、制备方法及体外评价方法进行综述。结果该制剂可以延长药物在胃内的滞留时间,提高生物利用度。结论随着研究的深入,漂浮-生物黏附制剂将逐步受到重视,成为常用的药物新剂型之一。     

口服胃定位释药技术

口服胃定位释药系统可分为普通口服释药系统和胃内滞留型释药系统两类。本文主要介绍胃内滞留型释药系统中目前研究较多的胃内黏附型、胃内漂浮型和胃内膨胀型三种释药系统。     

胃滞留型给药系统研究概况

胃滞留制剂可以增加以胃肠道上部吸收为主的药物的吸收,延长药物作用时间,减轻药物在胃肠道的局部刺激,提高生物利用度。依据药物制剂在体内的大小、比重及作用机制分为漂浮型胃内滞留系统、膨胀型胃内滞留系统、生物黏附型胃内滞留系统等。     

Polymeric nanofibers: targeted gastro-retentive drug delivery systems

Background: Conventional oral dosage forms exhibit poor/low bioavailability due to incomplete release of drug and short residence time at the absorption site. Gastro-retentive drug delivery system (GRDDS) is particularly used to improve bioavailability of the drugs, which have narrow absorption window down in the levels of gastrointestinal tract and also to treat local disorders.

Purpose: The purpose of this review is to describe the utility of the nanofibers as gastro-retentive dosage form. From last few decades, formulation scientists have put extensive efforts to develop suitable gastro-retentive drug delivery system, which is appropriate for commercialization. Current approaches used for preparation of gastro-retentive drug delivery system offers limited functional features to control the floating behavior. Recently, an extensive research has been developed to improve the gastric residence time by using nanofibers, which ultimately leads to the increased bioavailability of the drug. Multiple functional features and unique properties of nanofibers improve its gastro retention.

Conclusion: Nanofiber system provides stomach-specific drug release for longer duration; moreover, increased local action of the drug due to prolonged contact time with the gastric mucosa. Thus, the nanofiber system promises to be the potential approach for gastric retention drug delivery system.     

Development of a gastroretentive pulsatile drug delivery platform

Objectives To develop a novel gastroretentive pulsatile drug delivery platform by combining the advantages of floating dosage forms for the stomach and pulsatile drug delivery systems. Methods A gastric fluid impermeable capsule body was used as a vessel to contain one or more drug layer(s) as well as one or more lag‐time controlling layer(s). A controlled amount of air was sealed in the innermost portion of the capsule body to reduce the overall density of the drug delivery platform, enabling gastric floatation. An optimal mass fill inside the gastric fluid impermeable capsule body enabled buoyancy in a vertical orientation to provide a constant surface area for controlled erosion of the lag‐time controlling layer. The lag‐time controlling layer consisted of a swellable polymer, which rapidly formed a gel to seal the mouth of capsule body and act as a barrier to gastric fluid ingress. Key findings By varying the composition of the lag‐time controlling layer, it was possible to selectively program the onset of the pulsatile delivery of a drug. Conclusions This new delivery platform offers a new method of delivery for a variety of suitable drugs targeted in chronopharmaceutical therapy. This strategy could ultimately improve drug efficacy and patient compliance, and reduce harmful side effects by scaling back doses of drug administered.     

Gastroretentive drug delivery systems

A controlled drug delivery system with prolonged residence time in the stomach is of particular interest for drugs that i) are locally active in the stomach, ii) have an absorption window in the stomach or in the upper small intestine, iii) are unstable in the intestinal or colonic environment, or iv) exhibit low solubility at high pH values. This article gives an overview of the parameters affecting gastric emptying in humans as well as on the main concepts used to design pharmaceutical dosage forms with prolonged gastric residence times. In particular, bioadhesive, size-increasing and floating drug delivery systems are presented and their major advantages and shortcomings are discussed. Both single- and multiple-unit dosage forms are reviewed and, if available, results from in vivo trials are reported.     

Drug release kinetics and physicochemical characteristics of floating drug delivery systems

Introduction: Absorption of drugs through the gastrointestinal tract poses a variety of limitations, making the in vivo performance of drug delivery systems uncertain. Following on from recent advances, in a time of increased consideration of floating drug delivery systems, it is as important as ever to continue the progress by studying different aspects of these systems. Moreover, it seems imperative to gain a deeper insight into drug release mechanisms, in order to design a more systematic and intellectual floating system.

Areas covered: This paper summarizes current approaches in the research and development of ideal floating drug delivery systems, from recent literature. Also, in order to have predictability and reproducibility in designing an efficient floating dosage form, some kinetic studies are mentioned, and the drug release mechanism from floating drug delivery systems is discussed.

Expert opinion: Developing an efficient floating dosage form is reliant on a better understanding of the relation between formulation variables and performance of the floating systems. Generally, the combination of two buoyancy mechanisms and gas-generating systems with swellable polymers would be beneficial for obtaining an appropriate floating lag time and duration of buoyancy, which in turn guarantees optimum efficiency of the pharmaceutical dosage form.     

胃滞留给药系统的研究开发进展

胃滞留型缓释给药系统可增加"窄吸收窗"药物的滞留时间、提高其生物利用度、增加患者顺应性等优点。近二三十年来各国学者对该类新型制剂开展了大量研究,取得不少进展。本文拟对漂浮型、黏附型以及膨胀型三种胃滞留缓释给药系统的设计思路、辅料应用、体内外释放行为等进行简要的介绍和评价,为胃滞留型缓释给药系统的研究开发提供科学依据。     

多单元胃漂浮给药系统研究进展

胃漂浮给药系统可以增加药物在胃中的滞留时间，从而增加药物的吸收，提高药物的生物利用度。按药物剂量的分配方式，胃漂浮给药系统可分为“一单元”和“多单元”给药系统（如微丸、微球等）。“多单元”较“一单元”胃漂浮给药系统有着药物释放吸收的个体差异小、可避免药物剂量的“全或无”现象、对胃刺激性小、可以将不同释放速率的药物单元组合等优点。本文介绍了目前国内外多单元胃漂浮给药系统的类型、制备方法、释药情况及其体内漂浮性能的研究方法。     

Visualized intravesical floating hydrogel encapsulating vaporized perfluoropentane for controlled drug release

Intravesical drug delivery is the main strategy for the treatment of bladder disorders. To reduce the relief arising from frequent intravesical instillation, mucoadhesive hydrogel was used for the controlled release of the drug. However, the viscosity of mucoadhesive gel might cause severe urinary obstruction and bladder irritation. To solve all these problems, a floating hydrogel delivery system was developed using perfluoropentane (PFP) as the floating agent. After intravesical instillation of the floating hydrogel, the increased temperature in bladder vaporized PFP, resulting in the generation of microbubbles in the hydrogel. Then, it can float in urine to avoid the urinary obstruction and bladder irritation. In this study, systematic experiments were conducted to investigate the influences of PFP vaporization on the morphology and floating ability of hydrogels. The floating process is much milder and safer than other floating methods published before. In addition, PFP had been used as contrast agent, which affiliated the monitoring of gels during the operation. Therefore, this new drug delivery system addresses the problems of conventional intravesical instillation and is promising for clinic use.     

漂浮药物传递系统的新进展——中空微球

目的介绍漂浮药物传递系统的新进展———中空微球,就胃排空的机理、中空微球的制备及体内外表征作一综述。方法查阅相关文献,进行整理和归纳。结果该剂型可以延长药物在胃内的滞留时间,改善药物吸收,从而提高生物利用度。结论中空微球作为漂浮药物传递系统的一种新剂型,具有广阔的发展前景     

载药中空微球研究进展

目的介绍载药中空微球的研究进展。方法对中空微球的制备方法以及体内外漂浮性能的评价方法进行综述。结果该剂型可以延长药物在胃内的滞留时间,提高生物利用度并减少给药次数。结论中空微球是具有开发潜力的漂浮系统,具有广阔的发展前景。     

胃漂浮片的研究进展

综述了胃漂浮片的释药机理、适用性、处方组成及制备中的关键影响因素等方面的内容，并列举一些新型剂型实例；综述。