新型介孔羟基磷灰石/壳聚糖-万古霉素药物释放系统复合材料的制备及体外抗菌和成骨能力

采用冷冻干燥法合成了介孔羟基磷灰石(HA)/壳聚糖(CS)-万古霉素(VCM)药物释放系统复合材料, 利用SEM, XRD和FTIR等方法对材料进行了表征. 结果证实CS与HA混合复合材料具有良好的孔径和孔隙率, 万古霉素吸附于复合材料的表面和内部. 细胞毒性实验[噻唑蓝(MTT)比色法]结果表明, 材料可以促进成骨细胞增殖且具有良好的细胞相容性. 体外抑菌实验结果证实此材料可长时间抑制耐甲氧西林金葡菌(MRSA)的生长, 具有良好的抑菌和杀菌能力. 细胞黏附实验结果表明, 成骨细胞附着于材料表面增殖并通过孔道延伸. 实时聚合酶链式反应(RT-PCR)实验结果表明, 在成骨相关标志产物胶原蛋白-1(COL-1)及骨形态发生蛋白-2(BMP-2)基因上均有较高的表达, 表明材料在体外可以促进成骨细胞生长, 具有良好的成骨能力.     

Preparation of rapidly disintegrating tablets containing itraconazole solid dispersions

The disintegratability of tablets prepared from two types of solid dispersions containing the water-soluble polymer TC-5 and the enteric polymer HP-55 as an excipient were compared. The disintegratability was better in the tablets of solid dispersions containing non-water-soluble HP-55 than those containing TC-5. In consideration of the dissolubility of solid dispersions containing HP-55, the mean diameter of the solid dispersion (coating powder) must be controlled to 120 microm or less, but as this markedly increases the adhesion/aggregation tendency of the particles (angle of repose: 47 degrees ), control of the adhesion/aggregation tendency emerged as another problem. Therefore, surface-modification was performed in a high-speed agitating granulator using 0.1% light anhydrous silicic acid as a surface modifier, and marked improvement in the flowability was observed. This made continuous tableting using a rotary tablet machine possible even with the poorly flowable solid dispersions. Also, in tableting of the solid dispersions, no recrystallization of amorphous itraconazole by the tableting pressure was observed, and the tablets maintained satisfactory dissolubility. Moreover, it was possible to obtain the rapidly disintegrating tablets with very satisfactory properties, i.e., a tablet hardness of 30 N or higher and a disintegration time of 30 s or less, by the addition of croscarmellose as a disintegrant at 2% to the surface-modified solid dispersion and selection of the tableting pressure at 4.5 kN.     

造孔剂对电泳沉积制备多孔HA涂层及其生物活性的影响

采用水热法制得的羟基磷灰石(HA)纳米粉体,分别与造孔剂葡萄糖(Glu)、壳聚糖(CS)、炭粉(C)3种微粒(＜38.5 μm)配置成质量比1∶1的悬浮液,电泳沉积 烧结制备钛基多孔HA涂层,并对制得的3种多孔HA涂层在模拟体液浸泡前后的表面形貌、化学组成及物相变化进行表征。 结果表明,经700 ℃烧结处理后制得的3种多孔HA涂层在1.5倍人体模拟体液中浸泡5 d后,多孔HA涂层表面均被层状生长的碳磷灰石颗粒完全覆盖,颗粒直径在5~25 μm,说明这些多孔HA涂层均具有良好的生物活性。 其中以CS为造孔剂制得的多孔HA涂层结合强度最高,达19.5 MPa,有望开发成为新型的人骨植入生物陶瓷材料。     

Properties of gastroretentive sustained release tablets prepared by combination of melt/sublimation actions of L-menthol and penetration of molten polymers into tablets

A novel floating sustained release tablet having a cavity in the center was developed by utilizing the physicochemical properties of L-menthol and the penetration of molten hydrophobic polymer into tablets. A dry-coated tablet containing famotidine as a model drug in outer layer was prepared with a L-menthol core by direct compression. The tablet was placed in an oven at 80°C to remove the L-menthol core from tablet. The resulting tablet was then immersed in the molten hydrophobic polymers at 90°C. The buoyancy and drug release properties of tablets were investigated using United States Pharmacopeia (USP) 32 Apparatus 2 (paddle 100 rpm) and 900 ml of 0.01 N HCl. The L-menthol core in tablets disappeared completely through pathways in the outer layer with no drug outflows when placed in an oven for 90 min, resulting in a formation of a hollow tablet. The hollow tablets floated on the dissolution media for a short time and the drug release was rapid due to the disintegration of tablet. When the hollow tablets were immersed in molten hydrophobic polymers for 1 min, the rapid drug release was drastically retarded due to a formation of wax matrices within the shell of tablets and the tablets floated on the media for at least 6 h. When Lubri wax? was used as a polymer, the tablets showed the slowest sustained release. On the other hand, faster sustained release properties were obtained by using glyceryl monostearate (GMS) due to its low hydrophobic nature. The results obtained in this study suggested that the drug release rate from floating tablets could be controlled by both the choice of hydrophobic polymer and the combined use of hydrophobic polymers.     

原位沉析法制备可吸收壳聚糖/羟基磷灰石棒材

利用原位沉析法制备出一种以壳聚糖 (Chitosan ,CS)为基体 ,羟基磷灰石 (Hydroxyapatite,HA)为填料的新颖的复合材料 ,系统研究了HA含量对复合材料的力学性能和吸水率的影响 .CS HA的弯曲强度为 6 7 8(MPa) ,弯曲模量为 3 3(GPa) ,剪切强度为 2 1 2 (MPa) ,压缩强度为 4 7 8(MPa) ,均比人的自然骨高 2～ 3倍 ,基本满足了作为骨折内固定材料的力学性能的要求 .HA加入到CS使CS HA复合材料的吸水率下降 ,有助于延缓其力学强度在湿态环境下的衰减     

Chitosan–hyaluronic acid hybrid film as a novel wound dressing: in vitro and in vivo studies

Wound dressing with high quality is a kind of highly demanded wound‐repairing products. In this article, chitosan (CS) and hyaluronic acid (HA) were used to fabricate a novel wound dressing. CS/HA composite films with high transparency could be fabricated on glass or poly(methyl methacrylate) (PMMA) substrates, but not on poly(tetrafluoroethylene) (PTFE) plate. Along with the increase of HA amount, the resulting films became rougher as detected by atomic force microscopy (AFM). Increased also are water contact angle and water‐uptake ratio. By contrast, increase of the HA amount weakened the water vapor permeability (WVP), bovine albumin adsorption, and fibroblast adhesion, which are desirable characteristics for wound dressing. In vivo animal test revealed that compared with the vaseline gauge the CS/HA film could more effectively accelerate the wound healing, and reduce the occurrence of re‐injury when peeling off the dressing again. These results demonstrate that the CS mixed with a little amount of HA may produce inexpensive wound dressing with good properties for practical applications. Copyright © 2007 John Wiley & Sons, Ltd.     

Variations in content and structure of glycosaminoglycans of the vitreous gel from different mammalian species

The vitreous of all species is composed of essentially the same type of extracellular matrix macromolecules organized to a transparent gel. In this study, the composition and fi ne chemical structure of the glycosaminoglycans (GAGs) in the vitreous gel from sheep and goat were determined and compared with those of human and pig vitreous gels. The results showed that, in all examined species; hyaluronan (HA) was the predominant GAG, whereas chondroitin sulphate (CS) was the minor one. In the vitreous gel of the most relative species, i.e. sheep and goat, higher amounts of both of HA and CS were estimated as compared with pig and human tissues. The distribution of hydrodynamic sizes of HA and CS was significantly differed among different species. All HA preparations consisted of molecules with great variability in hydrodynamic sizes. The relative proportions of the large HA molecules (size >1.8 x 10(6) kDa) were significantly higher in sheep and goat as compared with human and pig vitreous gel. The length of CS chains was also of larger size in sheep and goat (50 and 58 kDa, respectively) than the respective chains in human and pig vitreous gel (38 and 28 kDa, respectively). The sulphation patterns of CS preparations were determined following enzymic treatments, HPLC and capillary electrophoretic analyses. The human vitreous-derived CS chains showed quite different sulphation profile than that of CS isolated from other species, since 4-sulphated disaccharides were identified as the dominant moiety. In conclusion, significant compositional and structural variations between the vitreous matrixes of different species at the GAG level were identified. The functional significance of these species-dependent variations is discussed.     

原位复合法制备层状结构的壳聚糖/羟基磷灰石纳米材料

用原位复合法制备了高性能的壳聚糖/羟基磷灰石(CS/HA)纳米复合材料.用预先沉积的壳聚糖膜将含有羟基磷灰石前驱体的壳聚糖溶液与凝固液隔离,同时控制壳聚糖沉积与羟基磷灰石前驱体转化为羟基磷灰石的过程,使其缓慢且有序地进行.当pH值改变时,质子化的壳聚糖分子链在负电层诱导下有序沉积并形成层状结构与羟基磷灰石原位生成CS/HA,并实现二者分子级复合.XRD和TEM测试证实原位生成的磷酸盐是羟基磷灰石,且其颗粒长约为100nm,宽30～50nm.SEM结果表明,用原位复合法制备的材料具有层状结构,CS/HA(质量比100/5)纳米复合材料弯曲强度高达86MPa,比松质骨的高3～4倍,相当于密质骨的1/2,有望用于可承重部位的组织修复材料.     

羟基磷灰石/氧化铁复合涂层的制备及其诱导骨生长的生物活性

用电泳沉积法制得羟基磷灰石/壳聚糖/氧化铁(HA/CS/Fe2O3)复合涂层,经700 ℃烧结处理得到HA/Fe2O3复合涂层。 通过SEM、EDS、XRD、FT-IR、电化学和万能材料试验机等对复合涂层的表面形貌、物相组成、抗腐蚀性和结合强度进行了表征和测试,最后采用1.5SBF浸泡法对复合涂层的生物活性进行了评价。 结果表明,当悬浮液中的HA、CS与Fe2O3质量比为100∶100∶1时,所制得的HA/Fe2O3复合涂层表面粗糙,抗腐蚀性强,具有良好的诱导骨生长生物活性,基体与复合涂层结合强度可达27.5 MPa。     

Improving mechanical and biological properties of macroporous HA scaffolds through composite coatings

Interconnected porous hydroxyapatite (HA) scaffolds are widely used for bone repair and replacement, owing to their ability to support the adhesion, transfer, proliferation and differentiation of cells. In the present study, the polymer impregnation approach was adopted to produce porous HA scaffolds with three-dimensional (3D) porous structures. These scaffolds have an advantage of highly interconnected porosity (≈85%) but a drawback of poor mechanical strength. Therefore, the as-prepared HA scaffolds were lined with composite polymer coatings in order to improve the mechanical properties and retain its good bioactivity and biocompatibility at the same time. The composite coatings were based on poly(d,l-lactide) (PDLLA) polymer solutions, and contained single component or combination of HA, calcium sulfate (CS) and chondroitin sulfate (ChS) powders. The effects of composite coatings on scaffold porosity, microstructure, mechanical property, in vitro mineralizing behavior, and cell attachment of the resultant scaffolds were investigated. The results showed that the scaffolds with composite coatings resulted in significant improvement in both mechanical and biological properties while retaining the 3D interconnected porous structure. The in vitro mineralizing behaviors were mainly related to the compositions of CS and ChS powders in the composite coatings. Excellent cell attachments were observed on the pure HA scaffold as well as the three types of composite scaffolds. These composite scaffolds with improved mechanical properties and bioactivities are promising bone substitutes in tissue engineering fields.     

Hydroxypropyl methylcellulose based cephalexin extended release tablets: influence of tablet formulation,hardness and storage on in vitro release kinetics

The object of this study was to develop hydroxypropyl methylcellulose (HPMC) based cephalexin extended release tablet, which can release the drug for six hours in predetermined rate. Twenty-one batches of cephalexin tablets were prepared by changing various physical and chemical parameters, in order to get required theoretical release profile. The influences of HPMC, microcrystalline cellulose powder (MCCP), granulation technique, wetting agent and tablet hardness on cephalexin release from HPMC based extended release tablets were studied. The formulated tablets were also characterized by physical and chemical parameters. The dissolution results showed that a higher amount of HPMC in tablet composition resulted in reduced drug release. Addition of MCCP resulted in faster drug release. Tablets prepared by dry granulation was released the drug slowly than the same prepared with a wet granulation technique. Addition of wetting agent in the tablets prepared with dry granulation technique showed slower release. An increase in tablet hardness resulted in faster drug release. Tablets prepared with a wet granulation technique and having a composition of 9.3% w/w HPMC with a hardness of 10-12 kg/cm(2) gave predicted release for 6 h. The in vitro release data was well fit in to Higuchi and Korsmeyer-Peppas model. Physical and chemical parameters of all formulated tablets were within acceptable limits. One batch among formulated twenty-one batches was successful and showed required theoretical release. The effect of storage on in vitro release and physicochemical parameters of successful batch was studied and was found to be in acceptable limits.     

Loading behavior of {chitosan/hyaluronic acid}n layer-by-layer assembly films toward myoglobin: an electrochemical study

When {CS/HA}n layer-by-layer films assembled by oppositely charged chitosan (CS) and hyaluronic acid (HA) were immersed in myoglobin (Mb) solution at pH 5.0, Mb was gradually loaded into the {CS/HA}n films, designated as {CS/HA}n-Mb. The cyclic voltammetric (CV) peak pair of Mb FeIII/FeII redox couple for {CS/HA}n-Mb films on pyrolytic graphite (PG) electrodes was used to investigate the loading behavior of {CS/HA}n films toward Mb. The various influencing factors, such as the number of bilayers (n), the pH of Mb loading solution, and the ionic strength of solution, were investigated by different electrochemical methods and other techniques. The results showed that the main driving force for the bulk loading of Mb was most probably the electrostatic interaction between oppositely charged Mb in solution and HA in the films, while other interactions such as hydrogen bonding and hydrophobic interaction may also play an important role. Other polyelectrolyte multilayer (PEM) films with different components were compared with {CS/HA}n films in permeability and Mb loading, and electroactive probes with different size and surface charge were compared in their incorporation into PEM films. The results suggest that due to the unique structure of CS and HA, {CS/HA}n films with relatively low charge density are packed more loosely and more easily swelled by water, and have better permeability, which may lead to the higher loading amount and shorter loading time for Mb. The protein-loaded PEM films provide a new route to immobilize redox proteins on electrodes and realize the direct electrochemistry of the proteins.     

Development of fast disintegrating compressed tablets using amino acid as disintegration accelerator: evaluation of wetting and disintegration of tablet on the basis of surface free energy

A fast disintegrating compressed tablet was formulated using amino acids, such as L-lysine HCl, L-alanine, glycine and L-tyrosine as disintegration accelerator. The tablets having the hardness of about 4 kgf were prepared and the effect of amino acids on the wetting time and disintegration time in the oral cavity of tablets was examined on the basis of surface free energy of amino acids. The wetting time of the tablets increased in the order of L-lysine HCl, L-alanine, glycine and L-tyrosine, whereas the disintegration time in the oral cavity of the tablets increased in the order of L-alanine, glycine, L-lysine HCl and L-tyrosine. These behaviors were well analyzed by the introduction of surface free energy. When the polar component of amino acid was large value or the dispersion component was small value, faster wetting of tablet was observed. When the dispersion component of amino acid was large value or the dispersion component was small value, faster disintegration of tablet was observed, expect of L-tyrosine tablet. The fast disintegration of tablets was explained by the theory presented by Matsumaru.     

Development of a novel tablet machine for a tiny amount of powder and evaluation of capping tendency

A novel single punch tablet machine was developed for a tiny amount of powder sample. This tablet machine mainly consists of upper and lower punches, single die, and conical powder feeder equipped with micro-vibrators. By using the powder feeder, mass of discharged powder can be maintained constant even if a tiny amount of powder having poor flowability is used. Motions of both upper and lower punches can be set arbitrarily. Thus, this machine enables us to prepare tablets with a tiny amount of powder sample under the same compression mechanism as conventional rotary tablet machines. Performance of the developed tablet machine was evaluated in a continuous direct tableting using a model powder with poor flowability. Thirty-four tablets (195 mg×34) having acceptable properties can be successfully prepared using no more than 10.0 g of a powder sample. We then proposed a novel in-die evaluation method of capping tendency. A new phase diagram consisting of the elastic recovery energy and the plastic deformation energy was proposed. These energies were calculated from a force-displacement profile, continuously monitored by the developed tablet machine. The results indicate that by using the new diagram the capping tendency of tablets prepared from various model powders can be well discriminated. The developed tablet machine and proposed evaluation method can contribute to a significant cost reduction and speeding up of formulation studies of oral dosage form.     

Preparation and evaluation of tablets rapidly disintegrating in saliva containing bitter-taste-masked granules by the compression method.

The aim of this study was to prepare, using taste-masked granules, tablets which can rapidly disintegrate in saliva (rapidly disintegrating tablet), of drugs with bitter taste (pirenzepine HCl or oxybutynin HCl). The taste-masked granules were prepared using aminoalkyl methacrylate copolymers (Eudragit E-100) by the extrusion method. None of the drugs dissolved from the granules (% of dissolved, < 5%) even at 480 min at pH 6.8 in the dissolution test. However, the drugs dissolved rapidly in the medium at pH 1.2 in the dissolution test. Rapidly disintegrating tablets were prepared using the prepared taste-masked granules, and a mixture of excipients consisting of crystalline cellulose (Avicel PH-102) and low-substituted hydroxypropylcellulose (L-HPC, LH-11). The granules and excipients were mixed well (mixing ratio by weight, crystalline cellulose: L-HPC = 8:2) with 1% magnesium stearate, and subsequently compressed at 500-1500 kgf in a single-punch tableting machine. The prepared tablets (compressed at 500 kgf) containing the taste-masked granules have sufficient strength (the crushing strength: oxybutynin tablet, 3.5 kg; pirenzepine tablet, 2.2 kg), and a rapid disintegration time (within 20 s) was observed in the saliva of healthy volunteers. None of the volunteers felt any bitter taste after the disintegration of the tablet which contained the taste-masked granules. We confirmed that the rapidly disintegrating tablets can be prepared using these taste-masked granules and excipients which are commonly used in tablet preparation.     

Effect of immobilization of polysaccharides on the biocompatibility of poly(butyleneadipate‐co‐terephthalate) films

Aiming to improve the hydrophilicity, antibacterial activity, cytocompatibility, and hemocompatibility of poly(butyleneadipate‐co‐terephthalate) (PBAT) films, PBAT films were treated with ozone, grafted with chitosan (CS), and followed by covalent immobilization of either heparin (HEP) or hyaluronic acid (HA). The surface graft density of modified PBAT films was detected by X‐ray photoelectron spectroscopy (XPS) and dyeing. The surface roughness of PBAT films was measured using an atomic force microscope (AFM). After immobilizing CS, PBAT films acquired antibacterial activity against Staphylococcus aureus and Escherichia coli. The adsorption of human serum albumin (HSA) and human plasma fibrinogen (HPF) on PBAT–CS–HEP and PBAT–CS–HA films was lower compared to that of native PBAT. Moreover, HEP immobilization could effectively reduce platelet adhesion and prolong the blood coagulation time, thereby improving the blood compatibility of PBAT. In addition, the growth of L929 fibroblasts was improved for HEP or HA immobilized PBAT, suggesting this surface modification was non‐cytotoxic. Furthermore, PBAT–CS–HEP and PBAT–CS–HA exhibited higher cell proliferation than native PBAT. Copyright © 2009 John Wiley & Sons, Ltd.     

Polysaccharide films built by simultaneous or alternate spray: a rapid way to engineer biomaterial surfaces

We investigated polysaccharide films obtained by simultaneous and alternate spraying of a chitosan (CHI) solution as polycation and hyaluronic acid (HA), alginate (ALG), and chondroitin sulfate (CS) solutions as polyanions. For simultaneous spraying, the film thickness increases linearly with the cumulative spraying time and passes through a maximum for polyanion/CHI molar charge ratios lying between 0.6 and 1.2. The size of polyanion/CHI complexes formed in solution was compared with the simultaneously sprayed film growth rate as a function of the polyanion/CHI molar charge ratio. A good correlation was found. This suggests the importance of polyanion/polycation complexation in the simultaneous spraying process. Depending on the system, the film topography is either liquid-like or granular. Film biocompatibility was evaluated using human gingival fibroblasts. A small or no difference is observed in cell viability and adhesion between the two deposition processes. The CHI/HA system appears to be the best for cell adhesion inducing the clustering of CD44, a cell surface HA receptor, at the membrane of cells. Simultaneous or alternate spraying of CHI/HA appears thus to be a convenient and fast procedure for biomaterial surface modifications.     

Development of a rapid process monitoring method for dry-coated tableting process by using near-infrared spectroscopy

A nondestructive transmittance near-infrared (NIR) method for detecting off-centered cores in dry-coated (DC) tablets was developed as a monitoring system in the DC tableting process. Caffeine anhydrate was used as a core active pharmaceutical ingredient (API), and DC tablets were made by the direct compression method. NIR spectra were obtained from these intact DC tablets using the transmittance method. The reference assay was performed with HPLC. Calibration models were generated by partial least squares (PLS) regression and principal component regression (PCR) utilizing external validations. Hierarchical cluster analysis (HCA) of the results confirmed that NIR spectroscopy correctly detected off-centered cores in DC tablets. We formulated and used the Centering Index (CI) to evaluate the precision of core alignment and generated an NIR calibration model that could correctly predict this index. The principal component (PC) 1 loading vector of the final calibration model indicated that it could specifically detect the misalignment of tablet cores. The model also had good linearity and accuracy. The CIs of unknown sample tablets predicted by the final calibration model and those calculated through the HPLC analysis were closely parallel with each other. These results demonstrate the validity of the final calibration model and the utility of the transmittance NIR spectroscopic method developed in this study as a monitoring system in DC tableting process.     

Effect of pulverization of the bulk powder on the hydration of creatine anhydrate tablets and their pharmaceutical properties

The hydration behavior and expansion properties of untreated and pulverized creatine anhydrate (CRA) tablets were studied under 60 and 75%RH at 25 degrees C by using differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD). The tablet hardness of untreated and pulverized CRA tablets was significantly decreased after hydration. There was a linear relationship between the degree of hydration and the tablet hardness of untreated CRA tablets compressed at 1000 kg/cm2. In contrast, the relationship between the degree of hydration and the tablet hardness of pulverized CRA tablets was nonlinear. These results suggest that the reduction in hardness of pulverized CRA tablets does not depend solely on the hydration level of crystal water. PXRD analysis indicated that the diffraction pattern of the pulverized CRA powder was similar to that of the untreated CRA powder. However, the diffraction intensity of the pulverized CRA powder was slightly lower than that of the untreated CRA powder at high angle. The micropore radius of both untreated and pulverized CRA tablets was significantly increased after hydration, but analysis of the relationship between micropore radius and fractional hydration of crystal water showed that untreated CRA tablets were more affected than pulverized CRA tablets. Therefore, the reduction in tablet hardness depends not only on the hydration behavior but also on the crystal orientation of the CRA powder.     

庆大霉素对羟基磷灰石/壳聚糖复合材料性能的影响

羟基磷灰石/壳聚糖-庆大霉素(HA/CS-G)缓释材料为骨髓炎的定点缓释给药提供了一种有效的局部药物缓释体系。为了研究抗生素对羟基磷灰石/壳聚糖材料性能的影响,采用共沉淀法制备了HA/CS-G缓释材料。利用红外光谱(IR)、X射线衍射(XRD)和扫描电子显微镜(SEM)对材料进行了表征。以不载药的羟基磷灰石/壳聚糖(HA/CS)为对照,研究了庆大霉素对HA/CS复合材料抑菌性能、力学性能和降解性能等的影响。实验结果表明,HA/CS-G有良好的抑菌效果。负载庆大霉素后HA/CS的机械强度明显增强,而材料的降解速率有所下降。本文采用的二次成型技术显著增大了材料的机械强度。