Konjac glucomannan and xanthan gum as compression coat for colonic drug delivery:experimental and theoretical evaluations

Compression coated tablets for oral colon specific delivery systems were developed with a mixture polysaccharide of konjac glucomannan (KGM) and xanthan gum (XG) as the compression coat. Diffusion of cimetidine from compression coated tablets was investigated by release experiment in Vitro. 0.22U/mL β-mannanase was applied in the mimic colon solution. The structure of the mixture polysaccharide was studied by an atomic force microscope (AFM). The experimental results indicate that a KGM70 tablet with a 0.4 g coat is of good design, due to a less than 5% drug loss in the mimic upper gastrointestinal solution by the synergistic interaction between XG and KGM, and due to about 50% cumulative release in the mimic colon solution by degradation after 24 hours. The release mechanism and model are discussed based on different periods of drug release including the delay of the drug, the constant release without an enzyme and the delay of degradation. Under hydrolysis by β-mannanase, drug release from the tablet with KGM coat shows an exponential increase, while that from the dosage with the mixture polysaccharide coat is an approximately zero-order process in which the constant release rate relates to the release velocity of a non-degraded system, the content of KGM within the coat and the average molecular weight ratio of KGM to XG. It was found that XG was the framework of the polysaccharide mixtures by AFM, which is similar to the analysis results from experiments on drug release.     

包埋尿素的葡甘聚糖/黄原胶复合凝胶的制备及其释放特性

尿素的高效利用一直是环保型农业的一个非常重要的研究课题。本工作利用两种天然多糖魔芋葡甘聚糖（KGM）与黄原胶（XG）在形成凝胶过程中的协同作用以及简单的包埋工艺,制备了包埋尿素的KGM/XG复合凝胶,并系统地研究了不同组成的复合凝胶在不同温度和pH环境中尿素的释放特性。结果表明,不同组成的包埋尿素的复合干凝胶在中性水介质中的尿素释放行为表现出3个具有不同特征的阶段。在释放的初期,释放速率较快,尿素的累积释放率随时间显著上升;在第二阶段,尿素的释放与包埋达到基本平衡,期间尿素的累积释放率无明显增加;在释放时间达22～24 h后,进入第三阶段,溶胀的复合凝胶出现崩解,释放速率再度加快,并在32～45 h后达到释放平衡。各阶段的持续时间与复合凝胶的载药量、m_KGM/m_XG和介质的温度有关。介质的pH相似文献   

Modified katira gum for colon targeted drug delivery

The aim of the this study is to develop colon targeted drug delivery systems for Ibuprofen using grafted katira gum as a carrier. Polyacrylamide‐grafted katira gum was synthesized by grafting acrylamide onto katira gum in presence of varying concentration of ceric ammonium nitrate (CAN) as initiator. Elemental analysis, FTIR, TGA, DTA, DSC, and SEM were used to characterize the grafting of acrylamide onto katira gum. Matrix tablets containing various proportions of grafted katira gum were prepared by wet granulation method. All the formulations were evaluated for hardness, drug content, swelling index, and in vitro release studies in simulated gastric fluid, small intestinal fluid, and simulated colonic fluid with and without enzymes. Ibuprofen was used for controlled release study. The drug release mechanism was studied by fitting into Peppas model and was found to be supercase‐II transport. Matrix tablets containing 0.3 g of CAN/gm of acrylamide showed optimum value and retained its physical integrity in simulated gastric, small intestinal and colonic fluid, where as other composition disintegrated within 2 h of dissolution testing in pH 1.2 buffer, simulated gastric fluid. The results of this study indicates that Ibuprofen matrix tablet containing 60 wt % composition of the above grafted katira gum would be potential formulations in delivering the drug to the colon and the more susceptible for enzymatic degradation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Solid lipid nanoparticles loaded thermoresponsive pluronic–xanthan gum hydrogel as a transdermal delivery system

The aim of this study was to develop and investigate thermoresponsive hydrogel incorporating curcumin (Cur) for application as a transdermal delivery system. Cur was encapsulated within solid lipid nanoparticles via ultrasonic homogenization, and these were introduced into a thermoresponsive hydrogel composed of pluronic F68 (PF68) and F127 (PF127). The hydrogel composed of PF68 and PF127 in 10:90 ratio transformed from sol to gel at 29.3 °C close to skin temperature. The skin adhesiveness and adhesive strength of the hydrogel with 0.2% (w/w) of XG was 1.64 and 1.24 times higher than those of the hydrogel without XG, respectively. The physiochemical characteristics of prepared formulations were investigated via observation of particle size, polydispersity index, transmission electron microscopy, and scanning electron microscopy. Moreover, Fourier transform infrared spectroscopy analysis was performed at physiological temperature, which revealed lower hydrogen bonding intensity at gel phase than at sol phase. The cumulative amount of Cur that penetrated significantly increased compared with the Cur ethanol solution. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46004.     

Barium chloride crosslinked carboxymethyl guar gum beads for gastrointestinal drug delivery

A mild method for microencapsulation of sensitive drugs, such as proteins, employing a suitably derivatized carboxymethyl guar gum (CMGG) and multivalent metal ions like Ca⁺⁺ and Ba⁺⁺ is reported. Initially, guar gum is derivatized with carboxymethyl groups so that it forms durable, self‐standing microbeads when its solution is dropped into CaCl₂ or BaCl₂ solutions. The swelling data of Ca⁺⁺ and Ba⁺⁺ crosslinked beads suggest that Ba⁺⁺ crosslinks CMGG much more efficiently than Ca⁺⁺. The drug loading efficiency of these Ba⁺⁺/CMGG beads, as a function of concentration of both metal ion as well as drug, was then determined using Bovine Serum Albumin as a model drug. The ability of these beads to protect the drug from the acidic environment of the stomach was investigated. It was found that a very little amount of the drug is released from the beads when they are suspended in NaCl–HCl buffer of pH 1.2 for 6 h. The beads were also shown to release almost the entire encapsulated drug when exposed to TRIS–HCl buffer of pH 7.4. Thus, the results indicate that Ba⁺⁺ crosslinked carboxymethyl guar gum beads can be used for gastrointestinal drug delivery. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3084–3090, 2001     

Rheological properties and some applications for rhamsan and xanthan gum solutions

The rheological properties of solutions of xanthan gum (Kelzan® D) and three rhamsan gums, S-60, S-130 and S-194, are examined. Effects studied include those of temperature, concentration and (for the rhamsan gums) extent of side chain branching. Solutions of greater viscosity and elasticity at most shear rates result as the degree of branching increases. When compared with xanthan gum, S-194 is found to be less temperature sensitive and more stable to excess shear. The use of these polymers in two commercial applications, i.e. coal–water mixtures and timber preservative emulsions, is also examined. Several advantages are identified when rhamsan gums are used instead of xanthan gum in both cases.     

Carrageenan-guar gum microwave irradiated micro-porous interpenetrating polymer network: A system for drug delivery

A series of microwave irradiated IPN of Crg and GG have been synthesized and cross linking through hydrogen bonding was confirmed by FTIR spectroscopy. Thermal sensitivity at 48°C, degradation above 200°C is an emblem of uniqueness. We obtained micro rough surface morphology, hydrophilicity and muco-adhesion supporting S6 for targeted drug delivery. Honey comb like internal architecture will provide high mechanical strength. The sample S6 showed 72% drug release in 12 hours. Based on the results, it was concluded that the S6 can be used as target oriented controlled drug delivery devices enabling control over swelling and drug release.     

瓜胶及其衍生物在药物控制释放领域的研究进展

介绍了官能团衍生化、接枝共聚、交联等瓜胶衍生物的制备方法及影响因素、瓜胶及其衍生物在药物控制释放领域的应用现状,并指出改性瓜胶具有比原粉更好的药物控制释放效果,因此经过配方设计,瓜胶及其衍生物有望成为药物控制释放尤其是靶向结肠给药领域的理想载体。     

Synthesis and properties of degradable hydrogels of konjac glucomannan grafted acrylic acid for colon-specific drug delivery

In this paper, we reported the synthesis and properties of novel hydrogel systems designed for colon targeted drug delivery. The gels were composed of konjac glucomannan (KGM), copolymerized with acrylic acid (AA) and cross-linked by N,N-methylene-bis-(acrylamide) (MBAAm). The influence of various parameters on the equilibrium swelling ratios of the hydrogels was investigated. The swelling ratio was inversely proportional to the content of MBAAm. It was possible to modulate the degree of swelling of the gels by changing cross-linking density of the polymer. The gels' swelling ratio has sensitive respondence to the environmental pH value variation. The results of degradation test show that the hydrogels retain the enzymatic degradation character of KGM and they can be degraded for 52.5% in 5 days by Cellulase E0240. In vitro release of model drug 5-aminosalicylic acid (5-ASA) was studied in the presence of Cellulase E0240 in pH 7.4 phosphate buffer at 37 °C. The accumulative release percent of 5-ASA reached 95.19% after 36 h and the drug release was controlled by the swelling and degradation of the hydrogels.     

Oscillatory measurements for salad dressings stabilized with modified starch,xanthan gum,and locust bean gum

The rheological properties of low‐oil‐content food emulsions were analyzed with oscillatory tests within the linear viscoelastic region. The formulations of these salad dressings usually include modified starch because of its low cost and the special creamy texture that it affords. The combination of starch with other natural gums may improve the quality of the product. A reference emulsion containing 4% modified starch and four other formulations in which the starch was partially replaced by xanthan gum (0.4%), locust bean gum (0.4%), and synergistic blends of these gums (0.03 + 0.03% or 0.1 + 0.1%) were formulated. Gels before emulsification were studied for comparative purposes. All systems showed weak gel behavior. An empirical equation fitting the storage and loss modulus dependence on the frequency was applied. The loss tangent allowed us to compare the viscoelastic character of all the systems. The complex viscosity followed the power law in all cases, and the generalized Cox–Merz rule was applied. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 897–903, 2006     

Dendrimer as nanocarrier for drug delivery

Dendrimers are novel three dimensional, hyperbranched globular nanopolymeric architectures. Attractive features like nanoscopic size, narrow polydispersity index, excellent control over molecular structure, availability of multiple functional groups at the periphery and cavities in the interior distinguish them amongst the available polymers. Applications of dendrimers in a large variety of fields have been explored. Drug delivery scientists are especially enthusiastic about possible utility of dendrimers as drug delivery tool. Terminal functionalities provide a platform for conjugation of the drug and targeting moieties. In addition, these peripheral functional groups can be employed to tailor-make the properties of dendrimers, enhancing their versatility. The present review highlights the contribution of dendrimers in the field of nanotechnology with intent to aid the researchers in exploring dendrimers in the field of drug delivery.     

The effects of graphene oxide on the properties and drug delivery of konjac glucomannan hydrogel

Konjac glucomannan (KGM) hydrogel has good potential application in food and medical science, although to achieve this, the physical and mechanical properties need further improvement. In this study, graphene oxide (GO) was used to improve the functionality of KGM hydrogel. KGM/GO hydrogels were prepared by freezing the alkaline KGM/GO sols. Rotational rheometer was used to study the rheological properties of different alkaline KGM/GO sols. Fourier transform infrared, Raman, differential scanning calorimetry, thermogravimetric analyses, and scanning electron microscopy were used to evaluate the structure and properties of the hydrogels. In addition, different pH solutions and an in vitro assay were used to study the swelling property and the release behavior of KGM/GO hydrogels, respectively. The result revealed strong hydrogen‐bond interaction between KGM and GO. The incorporation of GO highly improved the gel properties of KGM/GO sol, higher thermal stability, and more compact structure of KGM/GO hydrogels. KGM/GO hydrogels showed better swelling properties in deionized‐distilled water and pH 7.2 PBS. The release of 5‐aminosalicylic acid (5‐ASA) from KGM/GO (KG4) hydrogel was different in various pH media, but the initial burst release effect was very severe. Therefore, incorporation of GO have a good potential in enhancing the properties of KGM hydrogel, but KGM/GO hydrogel is not an ideal carrier for 5‐ASA release. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45327.     

Stimuli-responsive hybrid microgels for controlled drug delivery: Sorafenib as a model drug

Microgels (MGs) are synthetic colloidal hydrogel particles made of three dimensional polymer networks. Their chemical composition is crucial for their use as intelligent drug release systems operated by temperature control. Herein, several MGs using N-isopropylacrylamide (Nipam)/N-isopropylmethacrylamide (Nipmam), chitosan and acrylic/methacrylic acid have been synthesized by free radical polymerization reactions (NC MGs) and the effects of surfactants and different reaction times on size and swelling properties have been investigated. MGs have been identified and characterized by dynamic light scattering and atomic force microscopy, and finally used to optimize the encapsulation protocol of the hydrophobic drug sorafenib. The drug delivery system here described has encapsulation efficiency of 40% and releases 10% of the entrapped drug over about 16 h after the temperature is raised above the volume phase transition temperature. Data suggest that MGs with optimized composition may act as properly instructed entities able to trap and release biomolecules following external stimuli.     

Some properties of xanthan gum in aqueous solutions: effect of temperature and pH

The properties of xanthan gum (XG) aqueous solutions were investigated by using viscometric, electrokinetic and surface tension measurements. The effects of polymer concentration, temperature and pH on the viscosity of the XG solutions were evaluated and discussed. Zeta potential data determined for XG solutions in water in the temperature range of 15–45 °C corroborated with the results obtained from the viscometric investigations suggest the occurence of conformational changes above 36 °C. The activation energy of flow and that associated with the electrophoretic migration of the charged particles were estimated for XG solutions in water. In acid medium, xanthan gum determines a slight decrease of the surface tension of pure water at all investigated temperatures.     

Simulation and experimental analysis of an intelligent tissue for controlled drug delivery

In this research, an antibiotic was loaded in the composites of polyethylene glycol (PEG), acrylamide (AAm) and acrylic acid (AAc) hydrogels matrices and their drug deliveries were tested. Effect of some parameters on the drug delivery was checked by UV‐spectrophotometer. Temperature enhancement considerably increased hydrogel swelling and the drug release in the AAc and AAm. A dynamic model based on the Maxwell–Stefan equation was developed to model the drug delivery of hydrogels. COMSOL software was also applied to simulate buffer diffusion inside the hydrogels.     

黄原胶接枝聚丙烯酸水凝胶的合成及吸附性能——对亚甲基蓝染料的吸附行为

以黄原胶和丙烯酸为原料,N,N’一亚甲基双丙烯酰胺为交联剂,过硫酸钾为引发剂在水溶液中制得黄原胶接枝聚丙烯酸水凝胶,研究了其对阳离子染料MB（亚甲基蓝）的吸附行为,及对MB@吸附热力学。结果表明,XG—g—PAA水凝胶对MB的吸附行为符合Langmuir吸附等温式,其相关系数为0．9949i。     

黄原胶-丙烯酰胺接枝共聚物对Cr~(3+)的吸附性能

以黄原胶为原料,丙烯酰胺为接枝单体,采用微波辐射聚合得到了黄原胶-丙烯酰胺接枝共聚物（XG-g-AM),利用红外光谱仪、X射线衍射仪对其结构进行表征。研究了 XG-g-AM对Cr³⁺的静态吸附行为,并根据吸附等温线研究了吸附热力学性质,结果表明：在研究的浓度范围内,XG-g-AM对Cr³⁺的吸附行为可用Freundlich等温式进行描述;吸附为自发的、吸热的熵增加过程,升高温度有利于吸附。     

Acrylamide‐grafted‐acacia gum polymer matrix tablets as erosion‐controlled drug delivery systems

Acrylamide was grafted onto acacia gum in different ratios (1 : 1, 1 : 3, and 1 : 5). The graft copolymers formed were characterized by FTIR, rheological measurements, and differential thermal analysis. Tablets were prepared from these polymers loaded with two antihypertensive drugs, viz., diltiazem hydrochloride and nifedipine. The in vitro release experiments were carried out in simulated gastric and intestinal conditions. The graft copolymer prepared in the ratio 1 : 5 of acacia gum : acrylamide matrix was found to be a suitable matrix to investigate the controlled release of diltiazem hydrochloride and nifedipine. The drug release continued up to 6 and 14 h, respectively, for diltiazem hydrochloride and nifedipine. The release mechanism was investigated by using the mathematical equations proposed by Higuchi, Hixson‐Crowell, and Kopcha. Based on the release kinetics data, a correlation was attempted between the erosion‐controlled release and the dissolution‐controlled release. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2245–2253, 2004     

Growth inhibition in calcium sulfate crystal using a copolymer in oil fields: theoretical study and experimental evaluations

A poly(itaconic acid-co-sodium vinylsulphonate) (PIASVS) was theoretically studied and experimentally evaluated as an inhibitory agent against the growth of calcium sulfate (CaSO₄) crystals, in both non-saline and saline solutions. Density functional theory revealed that the CaSO₄ crystal precipitation could be precluded through the effective pairing of Ca²⁺ and SO₄^2? ions by carboxylic group polymer heads and that, moreover, the Na⁺ cations of the sulphonate polymer heads could be easily replaced by Ca²⁺. With PIASVS concentration of 50 ppm, lower than what is required in oil recovery processes, the polymer inhibited 33% in CaSO₄ crystals growth in non-saline solution, but the salt increased the inhibitory performance of PIASVS up to 54%. Thermogravimetric analysis, scanning electron microscopy and X-ray diffractometry techniques showed that PIASVS changed the CaSO₄ crystal morphology from a bassanite phase in non-saline solution to a bassanite/gypsum mix. The crystal morphology observations along with the conductivity measurements confirmed the pairing of ions from dissolved CaSO₄ by NaCl and PIASVS. Dynamic light scattering revealed that, the PIASVS cluster size increased in non-saline solution but decreased in saline solutions, suggesting that NaCl increases the PIASVS solubility in aqueous solution. The performance of PIASVS as anti-scaling agent was found to be suitable for the conditions found in the Mexican oil reservoirs.     

Influence of glycerides–xanthan gum synergy on their performance as lubricants for water‐based drilling fluids

Water‐based fluids for drilling wells are an environmentally friendly alternative to oil‐based formulations typically used in the oil industry. Aqueous mixtures of nonionic monoglyceride surfactants (C6, C8, C10, C12, and C18 carbon chains) and xanthan gum (XG) were investigated with that purpose, correlating their lubricity and solubility in water, as well as using surface tension and contact angle measurements. The results showed that monoglycerides behave as excellent lubricants in water, with a steady decrease of the friction coefficient as the hydrocarbon chain length increased. Monoglycerides were able to reduce the friction coefficient even further when used in XG suspensions, suggesting that they are probably forming a complex with the polysaccharide that shows a synergy toward their performance as lubricants. Experiments of adsorption onto iron oxide nanoparticles also produced evidence of the interaction between these molecules, which favors their adsorption on the metal surface. These results indicate that interactions occurring in solution between the surfactants and the polysaccharide are crucial in the mechanism of action of these mixtures as lubricants in water‐based drilling fluids. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41085.