壳聚糖/酸活化凹凸棒黏土复合物对双氯芬酸钠的吸附及体外释放

目的研究壳聚糖/酸活化凹凸棒黏土(酸化凹土)复合物对双氯芬酸钠的吸附作用和体外释放性能。方法采用紫外分光度法讨论复合物中壳聚糖的体积、pH值、吸附时间对吸附率和累积释放度的影响。结果在吸附介质pH=7和吸附4 h条件下,复合物对双氯芬酸钠的吸附率和释放度可达到80%以上。结论壳聚糖/酸化凹土复合物对双氯芬酸钠具有较好的吸附和释放性能,体外释放符合Higuchi方程。     

Multiunit Controlled-Release Diclofenac Sodium Capsules Using Complex of Chitosan with Sodium Alginate or Pectin

This study explored the application of chitosan–alginate (CA) and chitosan–pectin (CP) complex films as drug release regulator for the preparation of multiunit controlled-release diclofenac sodium capsules. Pellets containing drug and microcrystalline cellulose, in a ratio of 3:5, were prepared in a fluidized rotary granulator. The pellets were coated with CA, CP, sodium alginate, pectin, and chitosan solutions. The pellets, equivalent to 75 mg drug, were filled into capsules. After 2 h of dissolution test in acidic medium, the amount of the drug released from any preparation was negligible. The pellets were further subject to pH 6.8 phosphate buffer. More than 80% drug release at 12 h was observed with the uncoated pellets and those coated with sodium alginate, pectin or chitosan. Both 1% CA and 3% CP coated pellets exhibited drug release profiles similar to that of Voltaren SR75. It was found that approximately 60% and 85% of the drug were released at 12 and 24 h, respectively. Both Differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FTIR) analyses revealed complex formation between chitosan and these anionic polymers. It could be concluded that CA and CP complex film could be easily applied to diclofenac sodium pellets to control the release of the drug.     

Chitosan drug binding by ionic interaction.

Three model drugs (insulin, diclofenac sodium, and salicylic acid) with different pI or pKa were used to prepare drug-chitosan micro/nanoparticles by ionic interaction. Physicochemical properties and entrapment efficiencies were determined. The amount of drug entrapped in the formulation influences zeta potential and surface charge of the micro/nanoparticles. A high entrapment efficiency of the micro/nanoparticles could be obtained by careful control of formulation pH. The maximum entrapment efficiency did not occur in the highest ionization range of the model drugs. The high burst release of drugs from chitosan micro/nanoparticles was observed regardless of the pH of dissolution media. It can be concluded that the ionic interaction between drug and chitosan is low and too weak to control the drug release.     

Multiunit controlled-release diclofenac sodium capsules using complex of chitosan with sodium alginate or pectin

This study explored the application of chitosan-alginate (CA) and chitosan-pectin (CP) complex films as drug release regulator for the preparation of multiunit controlled-release diclofenac sodium capsules. Pellets containing drug and microcrystalline cellulose, in a ratio of 3:5, were prepared in a fluidized rotary granulator. The pellets were coated with CA, CP, sodium alginate, pectin, and chitosan solutions. The pellets, equivalent to 75 mg drug, were filled into capsules. After 2 h of dissolution test in acidic medium, the amount of the drug released from any preparation was negligible. The pellets were further subject to pH 6.8 phosphate buffer More than 80% drug release at 12 h was observed with the uncoated pellets and those coated with sodium alginate, pectin or chitosan. Both 1% CA and 3% CP coated pellets exhibited drug release profiles similar to that of Voltaren SR75. It was found that approximately 60% and 85% of the drug were released at 12 and 24 h, respectively. Both Differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FTIR) analyses revealed complex formation between chitosan and these anionic polymers. It could be concluded that CA and CP complex film could be easily applied to diclofenac sodium pellets to control the release of the drug.     

双氯芬酸钠药物树脂复合物的体外释放特性

目的:制备双氯芬酸钠药物树脂复合物,对其体外释药动力学进行考察。方法:采用不同交联度的离子交换树脂以静态法制备双氯芬酸钠药物树脂复合物并对双氯芬酸钠药物树脂复合物释放的影响因素进行考察。结果:随着树脂交联度的减小,树脂对双氯芬酸钠的载药速率变快,载药量增加。体外释药动力学研究表明,双氯芬酸钠药物树脂的释药速率随着温度的升高和溶出介质中离子强度的增大而加快;而且与树脂本身性质也有关,释药速率随着树脂交联度和粒径的减小而增大;双氯芬酸钠药物树脂的释放为pH依赖型。结论:双氯芬酸钠药物树脂的释药速率与释放温度、溶出介质的离子强度和pH值及树脂交联度和粒径有关。     

Preparation and in vitro evaluation of sustained release tablet formulations of diclofenac sodium

The effects of formulation variables on the release profile of diclofenac sodium (DS) from hydroxypropylmethyl cellulose (HPMC) and chitosan matrix tablets were studied. DS tablets were prepared by wet granulation and direct compression methods and different ratios of HPMC and chitosan were used. Physical properties of the prepared tablets and targeted commercial sustained release (SR) tablet and the drug release were studied in tablets that were placed in 0.1 M HCl for 1 h and phosphate buffer solution was added to reach pH value of 7.5. In vitro studies showed that 20% HPMC contained SR formulation with direct (dry) compression method is the optimum formulation due to its better targeting profile in terms of release. This formulation also exhibited the best-fitted formulation into the zero order kinetics. The precision and accuracy of the analytical method were also checked. The repeatability and reproducibility of the method were also determined.     

Development of enzyme-controlled colonic drug delivery using amylose and hydroxypropyl methylcellulose: optimization by factorial design

The aim of the present study is to develop colon-targeted drug delivery systems for diclofenac sodium which release the drug specifically and instantly at target site using amylose as a carrier. Coating formulations were designed based on the full factorial design. The evaluated responses were lag time prior to drug release and T90. Compression-coated tablets of diclofenac sodium containing various proportions of amylose and HPMC were prepared. In vitro drug release studies were done by changing pH method with enzyme. In vivo studies were done to confirm the potential of formulation to release the drug at target site. The dissolution data revealed that the ratio of polymers is very important to achieve optimum formulation. Results showed that the tablet prepared according to the above formulation released drug instantly at pH 6.8 (simulating colonic pH). An in vivo study shows that optimized formulation disintegrated in the target region. The results of this study revealed that factorial design is a suitable tool for optimization of coating formulations to achieve colon delivery. It was shown that coating formulation consisting of amylose 285 mg and HPMC 150 mg coating has the potential for colonic delivery of diclofenac sodium irrespective of change in pH in a patient with IBD.     

Release behaviour of diclofenac sodium dispersed in Gelucire® and encapsulated with alginate beads

Sustained release polymeric particles containing diclofenac sodium dispersed in Gelucire® matrix and encapsulated in calcium alginate shell were prepared with different drug-to-polymer ratios and also with different concentrations of sodium alginate for a fixed drug-to-polymer ratio in an aqueous environment. Spherical particles were formed by dropping an emulsion of diclofenac sodium in Gelucire® matrix, emulsified with sodium alginate, into calcium chloride solution. The gelled beads formed by ionotropic gelation of alginate with calcium ions showed sustained release of the water soluble drug in in-vitro release study. Drug release was a function of square-root of time, suggesting a matrix diffusion release pattern. The rate of release was significantly suppressed with increasing proportions of Gelucire® in the mixture. Sustained and complete release was achieved with Gelucire® of low melting point and low HLB value. No significant drug release occurred in a dissolution medium of pH 1.5, whereas complete release was observed at pH 6.8, consistent with considerable swelling of the alginate gel at this pH.     

Effect of sodium chloride on the release,absorption and safety of diclofenac sodium delivered by poloxamer gel

Poloxamer solutions prepared with poloxamers and sodium chloride were previously reported to undergo a phase transition to bioadhesive gels at body temperature. For the development of a thermosensitive diclofenac sodium-loaded poloxamer gel, here we investigated the effect of sodium chloride on the release, safety and rectal absorption in rats of diclofenac sodium delivered by the poloxamer gels. P 188 delayed the release rates of diclofenac sodium from poloxamer gels. However, sodium chloride showed no significant effect on the release rates of diclofenac sodium from poloxamer gels. Release mechanism analysis showed the release of diclofenac sodium was proportional to the time. The initial plasma concentrations of diclofenac sodium in the rectal formulation [diclofenac sodium/poloxamer 407 (P 407)/poloxamer 188 (P 188)/sodium chloride (2.5/15/17/0.8%)] were significantly higher compared with those in semi-solid suppository. Furthermore, it gave significantly faster Tmax of diclofenac sodium than did semi-solid suppository, indicating that the diclofenac sodium from poloxamer gel could be absorbed faster than that from semi-solid one in rats. It did not cause any morphological damage to the rectal tissues. These results suggested that poloxamer gel with sodium chloride could be a more effective and safe rectal delivery system of diclofenac sodium.     

Novel pH-sensitive citrate cross-linked chitosan film for drug controlled release

Turbidimetric titration revealed that there were electrostatic attractive interactions between citrate and chitosan in the pH region of 4.3-7.6, depending on their degree of ionization. Citrate cross-linked chitosan film was prepared simply by dipping chitosan film into sodium citrate solution. The swelling ratio of citrate/chitosan film was sensitive to pH, ionic strength etc. Under acidic conditions, citrate/chitosan film swelled and even dissociated in the pH less than 3.5, and the model drugs (brilliant blue and riboflavin) incorporated in the film were released quickly (usually within 2 h released completely in simulated gastric fluid at 37 degrees C) while under neutral conditions the swelling ratio of citrate/chitosan film was less significant and the release rate of brilliant blue and riboflavin was low (less than 40% released in simulated intestinal fluid in 24 h). Sodium chloride weakened the electrostatic interaction between citrate and chitosan, and therefore facilitated the film swelling and accelerated drug release. The parameters of film preparation such as citrate concentration, solution pH etc. influencing the film swelling and drug release profiles were examined. The lower concentration and the higher pH of citrate solution resulted in a larger swelling ratio and quicker riboflavin release. To improve the drug controlled release properties of citrate/chitosan film, heparin, pectin and alginate were further coated on the film surface. Among them only the coating of alginate prolonged riboflavin release noticeably (for 80% of drug released the time was extended from 1.5 to 3.5 h with 0.5% w/v alginate used). The results indicated that the citrate/chitosan film was useful in drug delivery such as for the site-specific drug controlled release in stomach.     

不同厂家双氯芬酸钠缓释胶囊体外释放度考察及Weibull分析

目的通过对4个不同厂家的双氯芬酸钠缓释胶囊进行体外释放度考察,为临床合理用药提供参考。方法采用2010年版中国药典二部附录溶出度第一法装置,以4种不同的溶出介质测定各样品不同时间的溶出量,以Weibull方程拟合最佳溶出介质的溶出参数,并进行数据分析。结果 pH=6.8的磷酸盐缓冲液作为体外释放环境较为理想,且根据t50、td等溶出参数显示,4个厂家双氯芬酸钠缓释胶囊除D厂样品溶出迟缓外,其他厂家均符合标准。结论该药的释放受pH值的影响较大,且不同厂家双氯芬酸钠缓释胶囊释放度有一定差异,在临床用药过程中,可作为参考依据。     

硝苯地平缓释凝胶的制备工艺及其释药性能研究

目的:制备硝苯地平缓释凝胶并考察其体外释药情况。方法:采用复凝聚法制备硝苯地平缓释凝胶,以壳聚糖、海藻酸钠的浓度、搅拌速度和壳聚糖溶液与海藻酸钠溶液的体积比为因素进行正交试验;用转篮法测定所制凝胶的释放度,通过改变释放介质的pH值,考察该缓释药物对pH的敏感性。结果:最佳工艺为壳聚糖浓度0.4%、海藻酸钠浓度1.5%、搅拌速度160r.min-1、壳聚糖溶液与海藻酸钠溶液的体积比为6:1。硝苯地平缓释凝胶在pH1.5的人工胃液中4h释放度为13.43%;在pH6.8的人工肠液中4h释放度为52.30%,12h释放度为81.72%。结论:所制硝苯地平缓释凝胶具有明显的缓释作用,体外释放具有较强的pH敏感性。     

双氯芬酸钠缓释制剂的释放度考察

目的:考察双氯芬酸钠缓释制剂的体外释放度.方法:采用转篮法和pH6.8的人工肠液对市售4个厂家的双氯芬酸钠缓释片和缓释胶囊的释放度进行了测定,并对释放度数据进行方程拟合及t检验.结果:A、C厂家产品的释放规律较符合Weibull方程,而B、D厂家产品的释放规律较符合Higuchi方程.各厂家产品的释放度在1 h,6 h时差异有显著性,在12 h时差异无显著性.结论:不同厂家双氯芬酸钠缓释制剂的释放度差异存在显著性.     

甲壳素对双氯灭痛缓释片溶出的影响

以pH 6.8磷酸盐缓冲液为释放介质,采用转蓝法测定了不同甲壳素含量的双氯灭痛缓释片的体外累体释放度。结果表明,随着片剂中壳素含量的增高、片剂溶出变慢,且溶出越符合零级释放。     

Tablet Formulation Study of Spray-Dried Sodium Diclofenac Enteric-Coated Microcapsules

Sodium diclofenac enteric-coated microcapsules were prepared by a spray-drying technique with Eudragit L 30D as enteric-coating material. The spray-dried powder, mixed with neocel or flo-starch, or the mixture of neocel and flo-starch (weight ratio, 1:1) was directly compressed into a tablet. The micromeritic properties of the spray-dried powder and the mixed powder for tableting were investigated. The flowability of the spray-dried powder was poor but improved after incorporating the excipients. The release rates of sodium diclofenac from the spray-dried powder, the mixed powder before tableting, and the tablets were determined in 0.1 N HC1 solution, pH 6.8, phosphate buffer solution, distilled water, and pH-changed medium. The results indicated that the spray-dried powder, the mixed powder before tableting, and the tablets all exhibited enteric-coated release properties; these powders and tablets showed some resistance to simulated gastric acid and then released drug more rapidly in pH 6.8 buffer solution. The weight ratio of neocel to flo-starch plays an important role in controlling the release of sodium diclofenac from enteric tablets. The 1:1 weight ratio of neocel to flo-starch was more suitable for designing the microdispersed sodium diclofenac enteric-coated tablets.     

Montmorillonite-Alginate Composites as a Drug delivery System: Intercalation and In vitro Release of Diclofenac sodium

Diclofenac sodium and alginate was intercalated into montmorillonite to form uniform sized beads by gelation method. The structure and surface morphology of the synthesized composite beads were characterized by powdered X-ray diffraction, Fourier transform infrared spectroscopy, thermo gravimetric analysis and scanning electron microscopy. Diclofenac release kinetics of the composite in simulated intestinal fluid medium (pH 7.4) and effect of montmorillonite content on the in vitro release of diclofenac from diclofenac-montmorillonite-alginate composites bead was investigated by UV/Vis spectrophotometer. Diclofenac encapsulation efficiency in the montmorillonite-alginate composites bead increases with an increase in the montmorillonite content. The control release of diclofenac from diclofenac-montmorillonite-alginate composites beads was observed to be better as compared to diclofenac-alginate beads.     

Formulation and evaluation of diclofenac sodium buccoadhesive discs

Twenty diclofenac sodium buccoadhesive discs containing Cp974p, polycarbophil, PEO, SCMC-medium viscosity (SCMC-MV), SCMC-ultrahigh viscosity (SCMC-UHV) or their combinations were prepared. These buccoadhesive discs were evaluated for release pattern, swelling capacity, surface pH, mucoadhesion performance, and in vitro permeation of diclofenac sodium through buccal membranes. In vivo testing of mucoadhesion time, strength of adhesion, irritation, bitterness due to drug swallowing and disc disintegration in the buccal cavity were also performed. Drug bioavailability of a selected diclofenac sodium buccoadhesive product was then compared with that of Voltarin 100 SR tablet. The percentage relative bioavailability of diclofenac sodium from the selected buccoadhesive disc 50 mg was found to be 141.31%.     

In-vitro and In-vivo Studies of the Diclofenac Sodium Controlled-release Matrix Tablets

Controlled release matrix tablets for diclofenac sodium were developed in this study. Five matrix-tablet formulations were prepared by granulating two viscosity grades of HPMC (hydroxylpropylmethylcellulose) in varying ratios with water in the planetary mixer. The in-vitro dissolution tests indicate that all five matrix formulations prolong the release of diclofenac sodium. The main factors controlling drug release were the HPMC viscosity grade and the amount of HPMC used. The larger the amount of high viscosity grade HPMC used, the slower the resultant release rate of diclofenac sodium. There was no significant degradation of diclofenac sodium or change in drug release rate in any of the five formulations during a three-month period of stability testing. The sustained release ability of four formulations was further demonstrated in an in-vivo study in six healthy subjects. There were in-vitro/in-vivo correlations between C_max, AUC_0–14, and the time for 50 or 80% drug to be released.     

Development and evaluation of natural gum-based extended release matrix tablets of two model drugs of different water solubilities by direct compression

The study was aimed at developing extended release matrix tablets of poorly water-soluble diclofenac sodium and highly water-soluble metformin hydrochloride by direct compression using cashew gum, xanthan gum and hydroxypropylmethylcellulose (HPMC) as release retardants. The suitability of light grade cashew gum as a direct compression excipient was studied using the SeDeM Diagram Expert System. Thirteen tablet formulations of diclofenac sodium (∼100 mg) and metformin hydrochloride (∼200 mg) were prepared with varying amounts of cashew gum, xanthan gum and HPMC by direct compression. The flow properties of blended powders and the uniformity of weight, crushing strength, friability, swelling index and drug content of compressed tablets were determined. In vitro drug release studies of the matrix tablets were conducted in phosphate buffer (diclofenac: pH 7.4; metformin: pH 6.8) and the kinetics of drug release was determined by fitting the release data to five kinetic models. Cashew gum was found to be suitable for direct compression, having a good compressibility index (ICG) value of 5.173. The diclofenac and metformin matrix tablets produced generally possessed fairly good physical properties. Tablet swelling and drug release in aqueous medium were dependent on the type and amount of release retarding polymer and the solubility of drug used. Extended release of diclofenac (∼24 h) and metformin (∼8–12 h) from the matrix tablets in aqueous medium was achieved using various blends of the polymers. Drug release from diclofenac tablets fitted zero order, first order or Higuchi model while release from metformin tablets followed Higuchi or Hixson-Crowell model. The mechanism of release of the two drugs was mostly through Fickian diffusion and anomalous non-Fickian diffusion. The study has demonstrated the potential of blended hydrophilic polymers in the design and optimization of extended release matrix tablets for soluble and poorly soluble drugs by direct compression.