新型胃滞留给药系统的研究进展

目的介绍新型胃滞留给药系统近年来的研究进展,为研究开发胃滞留制剂提供参考。方法通过查阅近年国内外相关文献,进行分析、整理和归纳。结果胃滞留给药系统能改善药物吸收,有效提高生物利用度,其中,以漂浮型、生物黏附型、膨胀型等三类胃滞留给药系统的研究较多。结论随着对胃滞留给药系统的深入研究,以及新型药用高分子材料的开发和制剂新技术的发展,胃滞留制剂具有广阔的应用前景。     

胃内漂浮给药系统的研究进展

胃内漂浮给药系统是通过制剂手段来延长胃内滞留时间,达到增加药物吸收,提高生物利用度的目的.就该类制剂的技术进步、性能评价及前景与局限性进行综述.     

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。     

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。     

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。     

胃内滞留释药系统的研究新进展

介绍近年来胃内滞留释药系统的研究进展。胃内滞留释药系统可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,提高药物生物利用度。目前胃内滞留释药系统主要有5种类型：胃内漂浮型、胃内黏附型、胃内膨胀型、胃底沉降型和磁性胃内滞留型。     

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。     

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。     

胃滞留型控释给药系统研究进展

口服给药是最方便且被应用最广的一种给药方式 ,目前市场上５０ %以上的药物是口服给药。口服控释剂型首先必须在胃肠维持长时间零级动力学过程释药 ,且释放的药物能被胃肠道有效吸收。一般口服药物吸收部位是在小肠上部和中部 ,更主要的是在小肠中１８０ｃｍ～３５０ｃｍ无菌部位 ,若药物需在胃中发挥作用或在小场上段吸收 ,则制成普通的控缓释制剂就不能提供比常规速释制剂更大的优势。胃滞留型制剂是近几年迅速发展起来的一种剂型 ,它通过驻留制剂在胃中长时间释放药物 ,药物一部分被胃吸收或在胃内发挥作用 ,另一部分通过幽门喷入小肠再…     

缓／控释制剂的国外研究动向

８０年代末，制剂研究开始转向新型给药系统。当前，研究最热门的仍为缓／控释给药系统。本文从胃内滞留型给药系统、脉冲式给药系统、结肠定位给药系统及自动调节给药系统４个侧面概述国外研究现状和发展趋势。     

Floating microspheres: to prolong the gastric retention time in stomach

A gastroretentive drug delivery system with prolong retention time in the stomach have great practical importance for drugs with an absorption window in the upper small intestine. Floating drug delivery system are expected to remain buoyant in the gastric content for prolong duration of time thus enhance the bioavailability of drugs. There are several gastroretentive drug delivery systems, which are floating microspheres, granules, tablets, powder, pills, laminated films and capsules. Floating microspheres are gaining special attention because of their wide applicability in the targeting of drug to stomach. Floating microspheres have several advantages, that they remain buoyant in the stomach and distributed uniformly to avoid the vagaries of gastric emptying and release the drug for prolong period of time.     

Gastroretentive dosage forms: a review with special emphasis on floating drug delivery systems

In the present era, gastroretentive dosage forms (GRDF) receive great attention because they can improve the performance of controlled release systems. An optimum GRDF system can be defined as a system which retains in the stomach for a sufficient time interval against all the physiological barriers, releases active moiety in a controlled manner, and finally is easily metabolized in the body. Physiological barriers like gastric motility and gastric retention time (GRT) act as obstacles in developing an efficient GRDF. Gastroretention can be achieved by developing different systems like high density systems, floating drug delivery systems (FDDS), mucoadhesive systems, expandable systems, superporous systems, and magnetic systems. All these systems have their own merits and demerits. This review focused on the various aspects useful in development of GRDF including the current trends and advancements.     

Gastroretentive floating drug-delivery systems: a critical review

The oral delivery of drugs with a narrow absorption window in the gastrointestinal tract (GIT) is often limited by poor bioavailability with conventional dosage forms due to incomplete drug release and short residence time at the site of absorption. To overcome this drawback and to maximize the oral absorption of these drugs, gastroretentive systems such as mucoadhesive, high-density, expandable, and floating systems have been developed. These systems provide controlled delivery of drugs with prolonged gastric residence time. However, in humans, differences in various physiological and biological factors can affect the gastric residence time and drug-delivery behavior from gastroretentive systems. Some floating drug-delivery systems (FDDS) have shown the capability to accommodate these variations without affecting drug release. This review mainly focuses on various physiological considerations for development of FDDS, and highlights recent technological developments including new dosage forms and their production techniques (e.g., holt-melt extrusion, melt pelletization, and pulsed plasma-irradiation processes). Alternatives to the existing in vitro compendial methods for evaluating floating dosage forms will be discussed, and a critical analysis of the existing literature on FDDS, identifying the potential areas for future research, is provided.     

Preparation and characterization of superporous hydrogels as gastroretentive drug delivery system for rosiglitazone maleate

BACKGROUND AND THE PURPOSE OF THE STUDY: Many drugs which have narrow therapeutic window and are absorbed mainly in stomach have been developed as gastroretentive delivery system. Rosiglitazone maleate, an anti-diabetic, is highly unstable at basic pH and is extensively absorbed from the stomach. Hence there is a need to develop a gastroretentive system. In this study a superporous hydrogel was developed as a gastroretentive drug delivery system. METHODS: Chitosan/poly(vinyl alcohol) interpenetrating polymer network type superporous hydrogels were prepared using a gas foaming method employing glyoxal as the crosslinking agent for Rosiglitazone maleate. Sodium bicarbonate was applied as a foaming agent to introduce the porous structure. Swelling behaviors of superporous hydrogel in acidic solution were studied to investigate their applications for gastric retention device. The optimum preparation condition of superporous hydrogels was obtained from the gelation kinetics. FT-IR, scanning electron microscopy, porosity and swelling ratio studies were used to characterize these polymers. In vitro drug release studies were also carried out. RESULTS: The introduction of a small amount of Poly(Vinyl Alcohol) enhanced the mechanical strength but slightly reduced the swelling ratio. The prepared superporous hydrogels were highly sensitive to pH of swelling media, and showed reversible swelling and de-swelling behaviors maintaining their mechanical stability. The degradation kinetics in simulated gastric fluid showed that it had biodegradability. Swelling was dependent on the amount of chitosan and crosslinker. The drug release from superporous hydrogels was sustained for 6 hrs. MAJOR CONCLUSION: The studies showed that chitosan-based superporous hydrogels could be used as a gastroretentive drug delivery system for rosiglitazone maleate in view of their swelling and prolonged drug release characteristics in acidic pH.     

Drug delivery strategies for the treatment of Helicobacter pylori infections

Helicobacter pylori is one of the most common pathogenic bacterial infections, colonising an estimated half of all humans. It is associated with the development of serious gastroduodenal disease - including peptic ulcers, gastric lymphoma and acute chronic gastritis. Current recommended regimes are not wholly effective and patient compliance, side-effects and bacterial resistance can be problematic. Drug delivery to the site of residence in the gastric mucosa may improve efficacy of the current and emerging treatments. Gastric retentive delivery systems potentially allow increased penetration of the mucus layer and therefore increased drug concentration at the site of action. Proposed gastric retentive systems for the enhancement of local drug delivery include floating systems, expandable or swellable systems and bioadhesive systems. Generally, problems with these formulations are lack of specificity, limited to mucus turnover or failure to persist in the stomach. Gastric mucoadhesive systems are hailed as a promising technology to address this issue, penetrating the mucus layer and prolonging activity at the mucus-epithelial interface. This review appraises gastroretentive delivery strategies specifically with regard to their application as a delivery system to target Helicobacter. As drug-resistant strains emerge, the development of a vaccine to eradicate and prevent reinfection is an attractive proposition. Proposed prophylactic and therapeutic vaccines have been delivered using a number of mucosal routes using viral and non-viral vectors. The delivery form, inclusion of adjuvants, and delivery regime will influence the immune response generated.     

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.     

Chitosan-based gastroretentive floating drug delivery technology: an updated review

INTRODUCTION: Gastroretentive floating drug delivery systems have emerged as efficient approaches for enhancing the bioavailability and controlled delivery of various therapeutic agents. Significant advancements exploiting chitosan have been made worldwide, in order to investigate these systems according to patient requirements, both in terms of therapeutic efficacy as well as patient compliance. Such systems precisely control the release rate of the target drug to a specific site, which facilitates an enormous impact on health care. AREAS COVERED: Different novel strategies have been undertaken for the development of various gastric floating dosage forms utilizing chitosan as a promising excipient. The present paper is an earnest attempt to provide new insights on various physicochemical and biological characteristics of chitosan, along with its potential applications in a wide array of biomedical approaches. Numerous and significant research findings in the vistas of chitosan-based gastroretentive floating drug delivery technology are also discussed. EXPERT OPINION: Chitosan has been considered as a unique and efficacious agent possessing a myriad spectrum of desired characteristics. It is emphasized that recent scientific advancements in the use of this excipient as a carrier will yield new generation gastroretentive drug delivery systems, with better pharmacotherapeutic interventions. Further studies are required to unveil the hidden beneficial properties of chitosan and its derivatives, to obtain newer delivery systems which may hold tremendous prospects in the near future.     

甲硝唑胃部滞留制剂的制备

目的为更好地清除幽门螺旋杆菌,制备同时具有缓释、漂浮、黏附特性的甲硝唑胃部滞留制剂。方法采用挤出滚圆法制备丸心,流化床包衣法制备甲硝唑缓释漂浮黏附微丸。EudragitNE30D为缓释层,NaHCO3为产气层,EudragitRL 30D为阻滞层,Carbopol 934P为黏附层,考察不同包衣增量情况下,各微丸的释药行为,在0.1 mol.L-1HCl中的漂浮性能,及离体大鼠胃黏膜上的黏附能力。结果丸心外包质量分数为3%的EudragitNE 30D,质量分数为9%的NaHCO3,质量分数为10%的EudragitRL 30D,质量分数为5%的Carbopol 934P的微丸,能实现缓释12 h、4 min起漂、持续漂浮12 h,漂浮率大于95%、黏附率为100%。结论所制备的甲硝唑胃部滞留制剂,同时具备缓释的释药行为、优良的漂浮能力、良好的黏附特征。进而能增加甲硝唑的胃部滞留时间,延长药物与幽门螺旋杆菌的接触时间,提高甲硝唑抗幽门螺旋杆菌的疗效。