黄原胶与HPMC的凝胶特性及释药机制

采用直接压片法，研究黄原胶与HPMC的凝胶特性。用称重法和体积测量法研究两种辅料分别在0．1mol／L盐酸和pH6．8磷酸盐缓冲液中的水合度及溶胀度，并以阿莫西林为模型药物进行体外释药研究。结果表明，在0．1mol／L盐酸中，HPMC的水合度及溶胀度均大于黄原胶，对药物释放阻滞作用较大；而在pH6．8磷酸盐缓冲液中则相反。药物在两种辅料中可通过骨架溶蚀和(或)凝胶层扩散呈零级或Higuchi型释药。     

几种亲水凝胶骨架材料相关性质的比较

以茶碱为模型药物,采用直接压片法制备亲水凝胶骨架片,从骨架片吸水性、膨胀性、溶蚀性及凝胶强度4个方面,全面比较了几种亲水凝胶骨架材料羟丙甲纤维素(hydroxypropylmethylcellulose,HPMC)、聚氧化乙烯(polyethylene oxide,PEO)、海藻酸钠[sodium alginate、低黏度NaAlg(L)、高黏度NaAlg(H)]和黄原胶(xanthan gum,XG)辅料性质和释药机制的差异。结果表明,吸水速率常数XG>>NaAlg(H)>PEO>NaAlg(L)>>HPMC;膨胀指数为XG>>PEO>>HPMC>>NaAlg;溶蚀速率NaAlg(L)>NaAlg(H)>>PEO80>PEO200>PEO300>XG≈PEO400≈K4M>K15M>PEO600≈K100M;凝胶层强度PEO>HPMC>XG>>NaAlg。对于PEO和HPMC骨架片,随着聚合物分子量增加,药物逐渐从以溶蚀机制为主的释放转移为以扩散机制为主的释放;对于NaAlg骨架片,药物主要以溶蚀机制释放;对于XG骨架片,药物主要以非Fick扩散机制释放。通过比较不同高分子材料之间的性能差异有助于合理设计和...     

Use of natural gums and cellulose derivatives in production of sustained release metoprolol tablets

Metoprolol tartrate sustained-release tablets (100 mg) were prepared using xanthan/guar gums and also hydroxypropyl methyl cellulose (HPMC) carboxymethyl-Cellulose (CMC) polymers by direct compression method. Physical characteristics of the tablets and water uptake in addition to their dissolution profiles were compared with standard (Lopressor® SR) tablets. Dissolution test was performed in the phosphate buffer solution (pH 6.8) and the samples were analyzed spectrophotometerically in 275.7 nm. Dissolution studies showed that formulations containing 100 and 80% of HPMC, 100% of guar, and 20% of xanthan followed the Higuchi model, while those containing 60 and 40% HPMC and 100 and 80% xanthan followed a zero-order model. The tablets with 40% xanthen followed a Hixon-Crowell model. In cellulose derivatives the highest MDT and dissolution efficiency until 8 hr (DE₈%) belonged to tablets with 40% HPMC, increasing the amount of CMC decreased the drug release rate, and formulations containing 60 and 40% of HPMC had the USP dissolution standards. While, in the gum formulations, the highest mean dissolution time and the lowest DE₈% belonged to tablets with 100% xanthan, increasing the xanthan decreased the release rate of metoprolol, and formulations containing 80 and 100% xanthan had the USP dissolution standards. Results showed that natural gums are suitable for production of sustained-release tablets of metoprolol.     

黄原胶亲水性骨架片体外释药的影响因素

以茶碱为模型药物,制备了黄原胶亲水性骨架片,研究了体外释药的影响因素．结果表明,茶碱黄原胶亲水性骨架片的释药速率与骨架片中黄原胶的用量和溶出条件（ 转速、介质离子强度、ｐＨ 值） 有关,但与制备工艺条件无关．溶出介质中离子对其释药机制有影响．黄原胶能有效控制骨架片中药物释放,是一种优良的亲水性骨架材料．     

Development and Evaluation of Microbial Degradation Dependent Compression Coated Secnidazole Tablets for Colonic Delivery

The present paper describes development of a polysaccharide based compression coated tablets of secnidazole for colon delivery. Core tablet containing secnidazole was compression coated with various proportions of guar gum, xanthan gum and chitosan, either alone or in combinations. Drug release studies were performed in simulated gastric fluid (SGF) for 2 h followed by simulated intestinal fluid (SIF, pH 7.4) up to 24 h. Secnidazole release from the prepared formulations was dependent on the type and concentration of polymer used in the formulation. Tablets coating containing either guar gum or xanthan gum showed ~30-40% drug release in 8 h. Further, in vitro dissolution studies of selected formulations performed in the dissolution media with rat caecal contents showed 54.48±0.24 - 60.42±0.16% of drug release. Formulations with single polymer in coating layer were unsuitable for targeting secnidazole release to colon region. Combination of chitosan with guar gum or xanthan gum exhibited control over secnidazole release.     

Development of Press-Coated,Floating-Pulsatile Drug Delivery of Lisinopril

Lisinopril is an angiotensin-converting enzyme (ACE) inhibitor, primarily used for the treatment of hypertension, congestive heart failure, and heart attack. It belongs to BCS class III having a half-life of 12 hrs and 25% bioavailability. The purpose of the present work was to develop a press-coated, floating-pulsatile drug delivery system. The core tablet was formulated using the super-disintegrants crosprovidone and croscarmellose sodium. A press-coated tablet (barrier layer) contained the polymer carrageenan, xanthan gum, HPMC K4M, and HPMC K15M. The buoyant layer was optimized with HPMC K100M, sodium bicarbonate, and citric acid. The tablets were evaluated for physical characteristics, floating lag time, swelling index, FTIR, DSC, and in vitro and in vivo behavior. The 5% superdisintgrant showed good results. The FTIR and DSC study predicted no chemical interactions between the drug and excipients. The formulation containing xanthan gum showed drug retaining abilities, but failed to float. The tablet containing HPMC K15M showed a high swelling index. The lag time for the tablet coated with 200 mg carrageenan was 3±0.1 hrs with 99.99±1.5% drug release; with 140 mg HPMC K4M, the lag time was 3±0.1 hrs with 99.71±1.2% drug release; and with 120 mg HPMC K15M, the lag time was 3±0.2 hrs with 99.98±1.7% drug release. The release mechanism of the tablet followed the Korsmeyer-Peppas equation and a first-order release pattern. Floating and lag time behavior have shown good in vitro and in vivo correlations.     

盐酸二甲双胍缓释骨架片的研制

目的:制备盐酸二甲双胍缓释骨架片.方法:采用亲水性高分子材料HPMC为骨架,制备盐酸二甲双胍缓释片,并用正交试验法优选制剂工艺.结果:以药物与20%HPMC K4M及乳糖适量混合,用10%PVP乙醇液为黏合剂,湿法制粒压片为最佳工艺.结论:本品制备工艺简便,药物体外释放接近Higuchi模型(Q=28.892 7t1/2 1.170 4,r=0.995),T50=2.87 h,Td=4.65 h,能维持药物12 h内缓慢释放.     

Matrix properties of a new plant gum in controlled drug delivery

A new plant gum, Okra (extracted from the pods of Hibiscus esculentus), has been evaluated as a controlled-release agent in modified release matrices, in comparison with sodium carboxymethyl cellulose (NaCMC) and hydroxypropylmethyl cellulose (HPMC), using Paracetamol as a model drug. Tablets were produced by direct compression and the in-vitro drug release was assessed in conditions mimicking the gastro intestinal system, for 6 h. Okra gum matrices provided a controlled-release of Paracetamol for more than 6 h and the release rates followed time-independent kinetics. The release rates were dependent on the concentration of the drug present in the matrix. The addition of tablet excipients, lactose and Avicel, altered the dissolution profile and the release kinetics. Okra gum compared favourably with NaCMC, and a combination of Okra gum and NaCMC, or on further addition of HPMC resulted in near zeroorder release of paracetamol from the matrix tablet. The results indicate that Okra gum matrices could be useful in the formulation of sustained-release tablets for up to 6 h.     

盐酸二甲双胍缓释片释药因素考察及处方筛选

目的制备盐酸二甲双胍缓释片并对释药因素进行考察。方法采用HPMC为基本骨架材料制备了盐酸二甲双胍骨架片 ,对影响释药的因素 ,如HPMC规格、粘合剂的种类、润滑剂的用量、制片工艺、制片压力及释放介质 pH等进行了考察 ,并在此基础上进行处方的筛选。结果盐酸二甲双胍缓释骨架片的体外释药行为符合Higuchi方程 ,HPMC规格和制片压力对盐酸二甲双胍骨架片的释药几乎无影响 ,而粘合剂的种类 ,润滑剂的用量 ,制片工艺对药物的释放产生一定的影响 ,介质的pH对药物释放的影响较大。结论采用HPMC作为基本骨架材料 ,结合其他辅料 ,制备了日服 1次的盐酸二甲双胍缓释片     

Properties of sustained release hot-melt extruded tablets containing chitosan and xanthan gum

The aim of this study was to investigate the influence of pH, buffer species and ionic strength on the release mechanism of chlorpheniramine maleate (CPM) from matrix tablets containing chitosan and xanthan gum prepared by a hot-melt extrusion process. Drug release from hot-melt extruded (HME) tablets containing either chitosan or xanthan gum was pH and buffer species dependent and the release mechanisms were controlled by the solubility and ionic properties of the polymers. All directly compressed (DC) tablets prepared in this study also exhibited pH and buffer species dependent release. In contrast, the HME tablets containing both chitosan and xanthan gum exhibited pH and buffer species independent sustained release. When placed in 0.1N HCl, the HME tablets formed a hydrogel that functioned to retard drug release in subsequent pH 6.8 and 7.4 phosphate buffers even when media contained high ionic strength, whereas tablets without chitosan did not form a hydrogel to retard drug release in 0.1N HCl. The HME tablets containing both chitosan and xanthan gum showed no significant change in drug release rate when stored at 40 °C for 1 month, 40 °C and 75% relative humidity (40 °C/75% RH) for 1 month, and 60 °C for 15 days.     

Formulation and In vitro assessment of sustained release terbutaline sulfate tablet made from binary hydrophilic polymer mixtures

In the present systematic study, a sustained release of terbutaline sulfate tablet (TBS) was developed and optimized by employing the hydrophilic polymers; chitosan and xanthan gum mixed with sodium bicarbonate as a release modifying agent. This formulation was developed using direct compression technology. In vitro release studies indicated rapid swelling and drug release in the initial period of the acid stage from a matrix composed of chitosan and xanthan gum solely. Addition of sodium bicarbonate to the matrix resulted in sustained drug release. Various formulation factors such as polymer to polymer ratio, polymer viscosity and particle size were altered and their effect on dissolution pattern was illustrated. Manufacturing variables such as compression force and lubricant percentage were investigated and found not to influence the drug release profile of the resulted tablets. The release mechanism follows Korsmeyer-Peppas equation with n value indicating non-Fickian diffusion. The release profiles were analyzed using statistical method (one-way ANOVA) and f₂ metric values and found to be similar to the commercial product Bricanyl^®. Reproducible data were obtained when scale-up of the formulation was performed.     

双氯芬酸钾羟丙基甲基纤维素骨架片体外释药的影响因素

目的考察影响双氯芬酸钾羟丙基甲基纤维素(HPMC)骨架片体外释放的各种因素。方法以HPMC为骨架材料,采用湿颗粒法制备双氯芬酸钾缓释片,考察药物/HPMC比、HPMC黏度、HPMC粒径、释放介质pH、压片压力及桨转速对药物体外释放行为的影响。结果药物/HPMC比、HPMC黏度和释放介质pH显著影响双氯芬酸钾释药速率,HPMC粒径、压片压力和桨转速对双氯芬酸钾释药速率影响较小。结论通过使用合适黏度的HPMC及调节药物/HPMC比可获得具有理想释药行为的双氯芬酸钾HPMC缓释片。     

Compaction, compression and drug release properties of diclofenac sodium and ibuprofen pellets comprising xanthan gum as a sustained release agent

Compaction and compression of xanthan gum pellets were evaluated and drug release from tablets made of pellets was characterised. Two types of pellets were prepared by extrusion-spheronisation. Formulations included xanthan gum, at 16% (w/w), diclofenac sodium or ibuprofen, at 10% (w/w), among other excipients. An amount of 500 mg of pellets fraction 1000-1400 microm were compacted in a single punch press at maximum punch pressure of 125 MPa using flat-faced punches (diameter of 1.00 cm). Physical properties of pellets and tablets were analysed. Laser profilometry analysis and scanning electron microscopy of the upper surface and the surface of fracture of tablets revealed that particles remained as coherent individual units after compression process. Pellets were flatted in the same direction of the applied stress evidencing a lost of the original curvature of the spherical unit. Pellets showed close compressibility degrees (49.9% for pellets comprising diclofenac sodium and 48.5% for pellets comprising ibuprofen). Xanthan gum pellets comprising diclofenac sodium experienced a reduction of 65.5% of their original sphericity while those comprising ibuprofen lost 49.6% of the original porosity. Permanent deformation and densification were the relevant mechanisms of compression. Fragmentation was regarded as non-existent. The release of the model drug from both type of tablets revealed different behaviours. Tablets made of pellets comprising ibuprofen released the model drug in a bimodal fashion and the release behaviour was characterised as Case II transport mechanism (release exponent of 0.93). On the other hand, the release behaviour of diclofenac sodium from tablets made of pellets was anomalous (release exponent of 0.70). For the latter case, drug diffusion and erosion were competing mechanisms of drug release.     

Effects of the Method of Preparation on the Compression,Mechanical, and Release Properties of Khaya Gum Matrices

A study has been made of the compression properties of khaya gum matrices and the effects of drug concentration and method of preparation of the material on the compression, mechanical and the drug release characteristics of the matrices. Khaya gum matrix tablets were prepared by direct compression and wet granulation methods. The compression properties of the formulations were assessed using the equations of Heckel and Kawakita. The mechanical properties of the tablets were evaluated using crushing strength and friability of the tablets, whereas the release properties of the tablets were evaluated by using the disintegration and dissolution times. The results obtained show that khaya gum deformed mainly by plastic deformation. The compression properties of the formulations were affected by the concentration of the drug and the method of preparation of the materials for compression. Tablets prepared by wet granulation showed faster onset and higher amount of plastic deformation during compression than those prepared by direct compression. Tablets containing dicalcium phosphate showed higher mechanical strength and disintegration and dissolution times. Wet granulation also increased the mechanical strength of the tablet without significantly affecting the drug release characteristics from the matrix tablets. Thus, the wet granulation method could be useful in the preparation of khaya gum matrix tablet with acceptable mechanical properties and drug release properties.     

米诺环素亲水凝胶型缓释骨架片的制备及体外释放度考察

目的:制备米诺环素亲水凝胶型缓释骨架片并考察其体外释放度。方法:采用粉末直接压片工艺制备缓释片;采用紫外分光光度法测定其释放度,同时考察羟丙基甲基纤维素(HPMC)的不同规格、用量以及不同释药条件对药物释放速率的影响。结果:所制制剂为黄色片剂,检查项符合2005年版《中国药典》中的相关规定。试验确定了以HPMCK100为缓释骨架材料,处方用量为32%;不同释放介质与释放装置对药物的释放均有显著影响。释放规律符合Higuchi方程。结论:该制剂处方工艺简单,体外释放度测定方法准确易行,制剂具有明显的缓释效果。     

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.     

Compression coated systems for colonic delivery of 5-fluorouracil

Compression coating is one of the approaches for delaying the release of drugs. The aim of this study was to develop colon-specific compression coated systems of 5-fluorouracil (5-FU) for the treatment of colorectal cancer using xanthan gum, boswellia gum and hydroxypropyl methylcellulose (HPMC) as the coating materials. Core tablets containing 50 mg of 5-FU were prepared by direct compression. The coating of the core tablets was done using different coat weights (230, 250, 275 and 300 mg) and different ratios (1:2, 2:1, 1:3, 1:7 and 3:4) of boswellia gum and xanthan gum and different ratios (1:1, 1:2, 2:1, and 2:3) of boswellia gum and HPMC. In-vitro release studies were carried out using simulated gastric and intestinal fluids, with and without rat caecal contents. Among the different ratios used for coating with boswellia:xanthan gum combination, ratio 1:3 gave the best release profile with the lowest coating weights of 230 mg (7.47 +/- 1.56% in initial 5 h). Further increase in the coat weights to 250, 275 and 300 mg led to drug release of 5.63 +/- 0.53%, 5.09 +/- 1.56% and 4.57 +/- 0.88%, respectively, in the initial 5 h and 96.90 +/- 0.66%, 85.05 +/- 1.01% and 80.22 +/- 0.35%, respectively, in 24 h. When coating was carried out using different ratios of the combination boswellia gum and HPMC, the ratio 2:3 gave the best results among the initial trial batches (7.80 +/- 0.57% in 5 h). Increasing the coat weights to 250, 275 and 300 mg led to drug release of 6.5 +/- 0.27%, 3.70 +/- 2.3% and 2.99 +/- 0.72%, respectively, in the initial 5 h and 96.90 +/- 0.66%, 85.05 +/- 1.01% and 80.22 +/- 0.35%, respectively, in 24 h. In-vitro studies were further carried out in the presence of 2% w/v rat caecal contents, which led to complete release of the drug from the tablets. Therefore, this study lays a basis for use of compression coating of 5-FU as a tool for delaying the release of the drug, which ensures better clinical management of the disease.     

卡托普利亲水凝胶缓释片的制备及体外释放影响因素

目的 :制备卡托普利亲水凝胶缓释片 ,并考察其体外释放影响因素。方法 :以羟丙基甲基纤维素为骨架材料 ,粉末直接压片制备卡托普利缓释片。以释放度为指标 ,评价多种因素对释放度的影响。结果与结论 :制得片剂体外释药行为符合Higuchi方程 ;羟丙基甲基纤维素用量达15 %即有缓释效果 ,用量为60 %时缓释效果最佳 ;MethocelK系列比60RT、75RT系列释放慢 ;填充剂以乳糖为佳 ,提高填充剂用量可明显减慢卡托普利的释放 ;浆法较转篮法释放略快 ;压片力和释放介质 pH值对溶出无明显影响。     

Formulation and evaluation of a sustained-release tablets of metformin hydrochloride using hydrophilic synthetic and hydrophobic natural polymers

Metformin hydrochloride has relatively short plasma half-life, low absolute bioavailability. The need for the administration two to three times a day when larger doses are required can decrease patient compliance. Sustained release formulation that would maintain plasma level for 8-12 h might be sufficient for daily dosing of metformin. Sustained release products are needed for metformin to prolong its duration of action and to improve patient compliances. The overall objective of this study was to develop an oral sustained release metformin hydrochloride tablet by using hydrophilic Eudragit RSPO alone or its combination with hydrophobic natural polymers Gum copal and gum damar as rate controlling factor. The tablets were prepared by wet granulation method. The in vitro dissolution study was carried out using USP 22 apparatus I, paddle method and the data was analysed using zero order, first order, Higuchi, Korsmeyer and Hixson-Crowell equations. The drug release study revealed that Eudragit RSPO alone was unable to sustain the drug release. Combining Eudragit with gum Copal and gum Damar sustained the drug release for more than 12 h. Kinetic modeling of in vitro dissolution profiles revealed the drug release mechanism ranges from diffusion controlled or Fickian transport to anomalous type or non-Fickian transport. Fitting the in vitro drug release data to Korsmeyer equation indicated that diffusion along with erosion could be the mechanism of drug release.     

Synthesis,characterization and evaluation of deacetylated xanthan derivatives as new excipients in the formulation of chitosan-based polyelectrolytes for the sustained release of tramadol

This paper addressed the application of deacetylated xanthan (XGDS) and chitosan (CTS) as a mixture blend forming hydrophilic matrices for Tramadol (TD) sustained release tablets. XGDSs derivatives were obtained by alkaline treatment of xanthan gum (XG) with various degrees of deacetylation (DD). The obtained products were characterized in terms of structural, thermal and physicochemical properties. Different tablet formulations containing CTS/XGDSs were prepared by direct compression method and compared to CTS/XG tablets. Flow properties of powder mixtures and pharmaceutical characteristics were evaluated. The dissolution test of TD was realized under simulated gastric and intestinal conditions to achieve drug release more than 24 h. All developed tablets were found conforming to standard evaluation tests. It was shown that CTS/XGDSs matrices ensure a slower release of TD in comparison with CTS/XG based formulations. Meanwhile, increasing DD resulted in a decrease of drug release. In addition, TD release from XGDS matrices was faster at pH (6.8) than at acidic pH (1.2). The matrix tablets based on CTS/XGDS4 (DD = 98.08%) were selected as the best candidates compared to the other systems in prolonging drug release. The optimal formulation was found to release 99.99% of TD after 24 h following a non-Fickian type.