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.     

Immersion coating of pellets with calcium pectinate and chitosan

This study has investigated the potential of immersion coating calcium containing pellet cores first with pectin, and then with two different cross-linkers, calcium or chitosan. The interaction between pectin and calcium, and between pectin and chitosan, are believed to slow down the drug release, and thereby, the coated pellets might possibly be used for colon specific drug delivery. Both the calcium coated pellets and the chitosan coated pellets had a reduced drug release compared to uncoated pellets in 0.1M HCl (1 h) and phosphate buffer pH 6.8 (4 h). The most successful combination had a drug release of only 17% during the entire test period in comparison to the uncoated pellets that had a drug release of 80%. When chitosan was used as a cross-linker, a higher reduction in drug release was obtained than by using calcium as the cross-linker. For the pellets coated with pectin in combination with chitosan, the type of pectin with a degree of methoxylation (DM) of 35 was superior to the pectin type with DM 17. The drug release was further slowed down by choosing a type of chitosan with a high degree of deacetylation (Dda) 89% and by coating at low concentrations (0.1%) in the immersion solution.     

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.     

The influence of Surelease and sodium alginate on the in-vitro release of tamsulosin hydrochloride in pellet dosage form

The objective of this study was to prepare controlled-release pellets containing 0.2 mg tamsulosin hydrochloride using a pelletizer-equipped piston extruder and double-arm counter-rotating rollers with Surelease and sodium alginate. The release of tamsulosin HCl from pellets coated with the commercial aqueous ethylcellulose dispersion (Surelease) was investigated at different coating loads. In addition, the effect of sodium alginate on drug release was investigated by varying the ratio of sodium alginate to microcrystalline cellulose (MCC). Dissolution studies were first performed in 500 mL simulated gastric fluid (pH 1.2) containing 0.003% (w/w) polysorbate 80 and then in simulated intestinal fluids (pH 7.2). The morphology of pellet surfaces and cross sections were examined by scanning electron microscopy (SEM). Apparently, the spherical pellets were prepared using a pelletizer-equipped piston extruder and double-arm counter-rotating rollers. The release profiles of tamsulosin HCl from Surelease-coated pellets were significantly affected by changing the content of Surelease, the pH of the dissolution medium and the ratio of sodium alginate to MCC. The drug release rates not only decreased with increase in the coating load, but also increased when the pH of the dissolution medium was increased from 1.2 to 7.2 regardless of the sodium alginate-to-MCC ratio. Moreover, the drug release rate at pH 7.2 was gradually increased by increasing the ratio of sodium alginate to MCC. SEM showed smooth surfaces of Surelease-coated pellets. These results suggest that Surelease and sodium alginate would be useful excipients in the preparation of controlled-release pellets with the desired release profiles.     

Coated chitosan pellets containing rutin intended for the treatment of inflammatory bowel disease: in vitro characteristics and in vivo evaluation

Preparation of coated pellets intended for rutin colon delivery, their evaluation in vitro and in vivo in experimental colitis in rats was the purpose of this study. Pellets were obtained using extrusion/spheronization and coated with three types of coatings (caffeic acid/hypromellose/alginic acid; sodium alginate/hypromellose/zinc acetate; sodium alginate/chitosan). Dissolution using buffers of pH values, β-glucosidase and times corresponding to gastrointestinal tract (GIT) was provided. Pellets coated with alginate/chitosan showed low rutin dissolution (12-14%) in upper GIT conditions and fast release (87-89%) under colon conditions; that is a good presumption of intended rutin release. After colitis induction and development, the rats were treated with pellets and rutin solution administered orally, solution also rectally. Colon/body weight ratio, myeloperoxidase activity and histological evaluation were performed. Rutin was able to promote colonic healing at the dose of 10mg/kg: colon/body weight ratio decreased and myeloperoxidase activity was significantly suppressed. Pellets coated with alginate/chitosan applied orally and rutin solution administered rectally showed the best efficacy. The combination of rutin as natural product, mucoadhesive chitosan degraded in the colon and sodium alginate as the main coating substance in the form of pellets create a promising preparation for therapy of this severe illness.     

多糖凝胶骨架结肠定位给药缓释系统的体外释放研究

目的: 筛选多糖材料作为水凝胶骨架,以达到结肠定位释药目的.方法: 选用海藻酸钠、果胶、壳聚糖、瓜木耳胶与药物混和制粒,灌装肠溶或结肠溶胶囊,考察其在人工胃液,人工肠液及人工结肠液中的释放情况.结果: 难溶性药物的海藻酸钠骨架结肠溶胶囊在人工胃液和小肠液中均不释放,人工结肠液中3 h释药低于30%;果胶骨架肠溶胶囊在人工胃液亦不释药,人工肠液中5 h释药仅为15%.水溶性药物在人工肠液中5 h释放可达50%.结论: 难溶性药物的海藻酸钠/结肠溶胶囊和果胶/肠溶胶囊体外释放度结果符合结肠定位的要求,可以作为建立酶触发体外释放评价方法和体内评价的制剂形式.水溶性药物的果胶/肠溶胶囊是较理想的缓释剂型.     

双氯芬酸钠脉冲控释微丸的研究

目的制备双氯芬酸钠脉冲控释微丸（DS-PRP）并考察体内外释药特性。方法采用水溶胀性材料为内包衣溶胀层，乙基纤维素水分散体为外包衣控释层制备DS-PRP，考察影响其体外释药的因素，并进行体内药代动力学研究。结果溶胀层材料类型、溶胀层和控释层包衣厚度、释放介质中十二烷基硫酸钠（SDS）的加入对DS-PRP的释药时滞和释药速率有显著影响，在0.1％ SDS溶液中释药时滞t_0.1为3.1 h，体内释药时滞tlag为2.8　h，与DS丸芯的相对生物利用度为（91±1２）%。结论DS-PRP在体内外均具有脉冲释药特性。     

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.     

Pectin/Ethylcellulose as film coatings for colon-specific drug delivery: preparation and in vitro evaluation using 5-fluorouracil pellets

The aim of the present study is to develop colon-targeted drug delivery systems for 5-fluorouracil using pectin combined with ethylcellulose as a film coat with fluidized bed coater. Pellets (0.8-1.0 mm in diameter) containing 40% 5-fluorouracil and 60% microcrystalline cellulose were prepared by extrusion and spheronization. Film-coated pellets of 5-fluorouracil containing various proportions (1:0, 0:1, 1:1, 1:2, w/w) of pectin and ethylcellulose (Surelease) were prepared and subjected to in vitro drug release. The amount of 5-fluorouracil released from pellets at different time intervals was estimated by high-performance liquid chromatography. Drug release was assessed using flow testing in the presence and absence of rat caecal contents. The film thickness is expressed as the theoretical percentage of the weight gained (TWG-%) used relative to the weight of the coated pellets. Coated pellets with pectin alone and TWG-20% released 100% of the 5-fluorouracil in the simulated gastric and small intestinal conditions and failed to control the drug release in the first 5 h of the dissolution study in the simulated gastric and small intestinal conditions; while coated pellets with ethylcellulose alone and TWG-20% released 11.7 +/- 0.9% of the 5-fluorourail at the end of 24 h. When the ratio of pectin to Surelease was 1:1 (w/w) and film coat TWG-20%, the release was rapid and was accompanied by splitting of the coat. When the ratio of pectin to Surelease was 1:2 (w/w) and film coat TWG-13% and TWG-20%, the formulations released 9.8 +/- 0.7% and 4.1 +/- 0.4%, respectively, of 5-fluorouracil in the first 5 h of the dissolution study in the simulated gastric and small intestinal conditions. When the dissolution study was continued in simulated colonic fluids (4% w/v rat caecal content medium) for another 19 h, the film coat with the formulations of TWG-13% and TWG-20% released 96 +/- 1.3% and 85.0 +/- 0.3%, respectively, of 5-fluorourail in simulated colonic fluids at the end of 24 h of the dissolution study, whereas in the control study the formulations released 51.4 +/- 1.0% and 34 +/- 0.5%, respectively, of 5-fluorouracil in absence of rat caecal contents at the end of 24 h. The results of the study show that the formulation of TWG-20% (pectin to Surelease 1:2, w/w) is most likely to provide targeting of 5-fluorouracil for local action in the colon, as it released only 4.1 +/- 0.4% of the drug in the simulated gastric and small intestinal conditions, and it released 85.0 +/- 0.3% of 5-fluorourail in simulated colonic fluids at the end of 24 h. The 5-fluorouracil-coated pellets showed no change in physical appearance, drug content, or dissolution pattern after storage at 40 degrees C/75% relative humidity for 6 months. Differential scanning calorimetric study indicated no possibility of interaction between 5-fluorouracil and pectin or other excipients used in the coated pellets.     

Alginate/chitosan particulate systems for sodium diclofenac release.

Alginate/chitosan particles were prepared by ionic gelation (Ca2+ and Al3+) for the sodium diclofenac release. The systems were characterized by electron microscopy and differential scanning calorimetry. The ability to release the active substance was examined as a function of some technological parameters and pH of dissolution medium. The release of sodium diclofenac is prevented at acidic pH, while is complete in a few minutes when pH is raised up to 6.4 and 7.2. The alginate/chitosan ratio and the nature of the gelifying cation allow a control of the release rate of the drug. The release mechanism was briefly discussed.     

Alginate-based pellets prepared by extrusion/spheronization: Effect of the amount and type of sodium alginate and calcium salts

Pellets containing microcrystalline cellulose (MCC), a model drug (theophylline) and a range of levels of sodium alginate (i.e., 10–50% w/w) were prepared by extrusion/spheronization. Two types of sodium alginate were evaluated with and without the addition of either calcium acetate or calcium carbonate (0, 0.3, 3 and 10% w/w). The effects of amount and type of sodium alginate and calcium salts on pellet properties, e.g., size, shape, morphology and drug release behavior, were investigated. Most pellet formulations resulted in pellets of a sufficient quality with respect to size, size distribution and shape. The results showed that the amounts of sodium alginate and calcium salts influenced the size and shape of the obtained pellets. However, different types of sodium alginate and calcium salt responded to modifications to a different extent. A cavity was observed in the pellet structure, as seen in the scanning electron micrographs, resulting from the forces involved in the spheronization process. Most of pellet formulations released about 75–85% drug within 60 min. Incorporation of calcium salts in the pellet formulations altered the drug release, depending on the solubility of the calcium salts used. The drug release data showed a good fit into both Higuchi and Korsmeyer–Peppas equations.     

Alginate-based pellets prepared by extrusion/spheronization: a preliminary study on the effect of additive in granulating liquid.

The aim of this study was to investigate the possibility of producing alginate-based pellets by extrusion/spheronization and also to improve the formation of spherical alginate-based pellets by investigating the effect of additive in granulating liquid on characteristics and drug release from resulting pellets. Two types of sodium alginate (30%) were evaluated in combination with theophylline (20%), microcrystalline cellulose (50%) and different granulation liquids. The pellets were then prepared in a basket extruder, then spheronized and dried. The final products were characterized by morphological examination and drug release study. Different additives in the granulating liquid influenced the ability of the extruded mass to form pellets (the processability) with this technique. However, different sodium alginate types responded to shape modifications to a different extent. Long, dumbbell-shaped pellets were obtained with viscous granulating liquids. However, short, nearly spherical pellets were obtained with watery granulation liquid with calcium chloride that reduced the swelling ability of sodium alginate. Improvements in the pellet characteristics were also dependent on the sodium alginate type employed. Most of pellet formulations released about 75-85% drug within 60min and showed a good fit into both Higuchi and Korsmeyer-Peppas equations. Higher amount of 3% calcium chloride, as a granulating liquid, in the formulation showed higher mean dissolution time resulting from the cross-linking properties of calcium ions to the negative charges of alginate molecules.     

泮托拉唑钠肠溶微丸的制备

以泮托拉唑钠、羟丙甲纤维素、无水碳酸钠、吐温-80、十二烷基磺酸钠和水混合制成主药层包衣溶液.采用流化床包衣技术,对空白丸芯依次包主药层、隔离层和肠溶层,制得泮托拉唑钠肠溶微丸,并优化了处方和工艺.将所得肠溶微丸装入普通胶囊中制成泮托拉唑钠肠溶微丸胶囊,3批制品在pH 6.8磷酸盐缓冲液中45 min时的释放度分别为(97.6±1.1)%、(98.1±1.3)%、(98.4±1.9)%,在0.1 mol/L盐酸中2h时的释放量分别为(2.9±1.7)%、(2.9±1.4)%、(2.3±2.1)%.     

Optimization of drug release from compressed multi unit particle system (MUPS) using generalized regression neural network (GRNN)

The purpose of this study was development of diclofenac sodium extended release compressed matrix pellets and optimization using Generalized Regression Neural Network (GRNN). According to Central Composite Design (CCD), ten formulations of diclofenac sodium matrix tablets were prepared. Extended release of diclofenac sodium was acomplished using Carbopol® 71G as matrix substance. The process of direct pelletisation and subsequently compression of the pellets into MUPS tablets was applied in order to investigate a different approach in formulation of matrix systems and to achieve more control of the process factors over the principal response — the release of the drug. The investigated factors were X₁ -the percentage of polymer Carbopol® 71 G and X₂- crushing strength of the MUPS tablet. In vitro dissolution time profiles at 5 different sampling times were chosen as responses. Results of drug release studies indicate that drug release rates vary between different formulations, with a range of 1 hour to 8 hours of dissolution. The most important impact on the drug release has factor X₁ -the percentage of polymer Carbopol® 71 G. The purpose of the applied GRNN was to model the effects of these two causal factors on the in vitro release profile of the diclofenac sodium from compressed matrix pellets. The aim of the study was to optimize drug release in manner wich enables following in vitro release of diclofenac sodium during 8 hours in phosphate buffer: 1 h: 15–40%, 2 h: 25–60%, 4 h: 35–75%, 8 h: >70%.     

结肠定位释药双氯芬酸钠包衣片体内外相关性

目的研制时间依赖型口服结肠定位释药双氯芬酸钠包衣片。方法用释放度测定法研究双氯芬酸钠包衣片体外释放行为 ,用HPLC法测定包衣片在家犬体内的血药浓度 ,并计算出相关参数 ,进行体内外相关性考察。结果体外平均延迟释放时间为 4～ 5h时 ,体内平均时滞为 3～ 6h ,达到预期结果。结论本文研制的双氯芬酸钠片有进一步开发的价值     

The influence of chitosan and sodium alginate and formulation variables on the formation and drug release from pellets prepared by extrusion/spheronisation

The influence of the incorporation of two oppositely charged hydrophilic natural polymers, chitosan and sodium alginate, alone and in combination, on the ability of formulations containing a model drug (paracetamol) to form spherical pellets by the process of extrusion/spheronisation and the properties of the pellets, has been undertaken. A statistically experimental design was employed to allow the major factors which determined the properties of the pellets, to be identified. A standardised procedure was used to prepare the pellets with a ram producing the extrudate for spheronisation. Statistical analysis of the results indicated that the formulation variables of the type and level of the polymer, the proportion of the model drug, and the proportion of the microcrystalline cellulose influenced (a) the quantity of liquid binder required to produce a good formulation (narrow size range and high value for the shape factor indicating sphericity), (b) the steady-state extrusion force, (c) the pellet perimeter, (d) the apparent pellet density and (e) the porosity of the pellets. The median size of the pellets of the "good formulation" could only be related to the chitosan and sodium alginate content of the formulations. The proportion of the drug, chitosan and sodium alginate content of the formulation significantly influenced the in vitro dissolution of the model drug (paracetamol). The drug release mechanism differed with the formulation variables, although if the pellets remained intact during the dissolution test, diffusion was the controlling mechanism. There was no significant advantage to be gained by using a mixture of the two polymers in terms of retarding drug release.     

双氯芬酸钠肠溶微丸型片剂的研制

本文制备了双氯芬酸钠肠溶微丸型片剂。以丙烯酸树脂EudragitNE30D和EudragitL30D-55不同比例的混合物作为衣膜材料，对不同粒径大小的双氯芬酸钠速释丸芯进行不同增重水平的包衣，并与不同压缩特性和用量比例的缓冲微丸混合，压片。所得的双氯芬酸钠肠溶微丸型片剂在人工胃液中2 h内累积释放百分数<10%，在人工肠液中1 h内累积释放百分数为(83±2.42)%。结果表明EudragitNE30D与EudragitL30D-55以一定比例混合制备得到适合压片的肠溶微丸，硬脂酸制备的缓冲微丸可用于微丸型片剂的制备。     

Properties of enteric coated sodium valproate pellets

The influence of subcoat application and micro-environmental pH on the dissolution properties of enteric coated sodium valproate pellets was investigated. The pellets were prepared by solution-layering or wet-mass extrusion-spheronization methods. In order to pass the USP enteric test, the solution-layered and wet-mass extruded pellets required 35 and 25% weight gain of Eudragit L 30D-55, respectively. The application of a subcoat of either Methocel-E5 (HPMC) or Opadry AMB to the pellets resulted in a delay in sodium valproate release in 0.1N HCl. Further delay in drug release was observed when citric acid was present in a HPMC subcoat or when added to the core pellet formulation. The amount of drug released from coated pellets was a function of the level of citric acid in the pellet core or subcoat and subsequent micro-environmental pH of the pellets. Citric acid exerted a plasticizing effect on the enteric polymer film and improved film formation and polymer coalescence. When greater than 10% (w/w) citric acid was present in the pellets, a decrease in drug content was observed due to the conversion of sodium valproate to the volatile compound, valproic acid. Pellets containing less than 10% (w/w) citric acid maintained potency during processing.     

双氯芬酸钠迟效制剂的药动学

目的 :以双氯芬酸钠普通肠溶片 (R)为对照 ,比较国产双氯芬酸钠迟效制剂 (T)的相对生物利用度和药动学。方法 :采用双交叉、自身对照的方法 ,将 2 4名受试者分为 2组 ,单剂量组分别口服T和R各 10 0mg ;多剂量组 ,每日分别口服T和R各10 0mg ,共 4d。结果 :单剂量组T和R的Cmax,Tmax,T1/2 ,MRT ,AUC0～τ分别为 (115 6±s 36 1)和(3910± 96 8) μg·L- 1,(3.0± 1.0 )和 (2 .3± 0 .5 )h ,(6 .6± 2 .3)和 (2 .9± 1.5 )h ,(12 .3± 2 .3)和 (4.4±1.0 )h ,(92 37± 994 )和 (874 5± 12 16 ) μg·h·L- 1,T的F为 (10 7± 12 ) %。多剂量口服T和R的Cav,FI分别为 (343± 4 6 ) μg·L- 1和 (333± 6 4) μg·L- 1,(2 5 4± 82 ) %和 (40 4± 97) %。结论 :2种制剂口服吸收相似 ,迟效制剂具有峰谷浓度差异小 ,血药浓度波动幅度小等缓释药动学特征。     

The influence of drug type on the release profiles from Surelease-coated pellets

The release of metoclopramide hydrochloride (a water-soluble cationic drug) and diclofenac sodium (a sparingly soluble anionic drug) from pellets coated with ethylcellulose from an aqueous ethylcellulose dispersion (Surelease) at different coating loads was investigated. The release rates of each drug decreased as the coating load of Surelease increased. However, despite its lower water solubility, diclofenac sodium was released slightly faster than metoclopramide hydrochloride at equivalent coating loads. Changes in the release rates after curing were more pronounced for metoclopramide hydrochloride and the release rates of diclofenac sodium were lower than those of metoclopramide hydrochloride after curing. Differences between the release behaviour of the two drugs were probably due to an interaction between the cationic metoclopramide and the anionic ammonium oleate present in the Surelease. The slower release of metoclopramide hydrochloride may be due to an in situ formation of a poorly soluble complex of the drug and the ammonium oleate. This complex, because of its large molecular size, may diffuse more slowly through the film, causing a reduction in the release rate of metoclopramide hydrochloride. This interaction may also account for the differences in release characteristics of the drugs after curing. During curing the surfactant, due to its unstable nature in heat, may be converted to its constituent components. The interaction of drug with the surfactant was reduced as the residue of the ammonium oleate decreased during curing. However, a relatively low volume flow rate of air, and therefore, slower removal of ammonia in the modified side-vented Manesty Accela-cota 10 may also have affected the coating process of the pellets.