吡嘧司特钾水凝胶骨架缓释片的研究

目的研制吡嘧司特钾(TBX)水凝胶缓释骨架片.方法以羟丙甲基纤维素(HPMC)为骨架材料,考察HPMC用量、黏度及压片压力等对主药体外释放速度的影响,优化处方工艺.结果所得片剂体外释放实验表明10h累积释放度＞75%,其释放行为符合Hguchi方程.HPMC的用量、黏度、制备方法及压片片力的大小等对TBX的释放速率均有显著影响.结论用高黏度的HPMC作为亲水凝胶骨架片的基质能达到较好的缓释作用.     

In vitro Evaluation of the Effect of Combination of Hydrophilic and Hydrophobic Polymers on Controlled Release Zidovudine Matrix Tablets

The aim of the present study was to prepare and characterize controlled-release matrix tablets of zidovudine using hydrophilic HPMC K4 M or Carbopol 934 alone or in combination with hydrophobic ethyl cellulose. Release kinetics was evaluated by using USP XXIV dissolution apparatus No.2 (paddle) type. Scanning electron microscopy was used to visualize the effect of dissolution medium on matrix tablet surface. The in vitro results of controlled – release zidovudine tablets were compared with conventional marketed tablet Zidovir. The in vitro drug release study revealed that HPMC K4 M or Carbopol 934 preparation was able to sustain the drug release near to 6 hours. Combining HPMC K4 M or Carbopol 934 with ethyl cellulose sustained the drug release for nearly 12 h. The in vitro evaluation showed that the drug release may be by diffusion along with erosion. Results suggest that the developed controlled-release tablets of zidovudine could perform therapeutically better than marketed dosage forms, leading to improve efficacy, controlling the release and better patient compliance.     

Floating matrix tablets based on low density foam powder: effects of formulation and processing parameters on drug release.

The aim of this study was to develop and physicochemically characterize single unit, floating controlled drug delivery systems consisting of (i). polypropylene foam powder, (ii). matrix-forming polymer(s), (iii). drug, and (iv). filler (optional). The highly porous foam powder provided low density and, thus, excellent in vitro floating behavior of the tablets. All foam powder-containing tablets remained floating for at least 8 h in 0.1 N HCl at 37 degrees C. Different types of matrix-forming polymers were studied: hydroxypropyl methylcellulose (HPMC), polyacrylates, sodium alginate, corn starch, carrageenan, gum guar and gum arabic. The tablets eroded upon contact with the release medium, and the relative importance of drug diffusion, polymer swelling and tablet erosion for the resulting release patterns varied significantly with the type of matrix former. The release rate could effectively be modified by varying the "matrix-forming polymer/foam powder" ratio, the initial drug loading, the tablet geometry (radius and height), the type of matrix-forming polymer, the use of polymer blends and the addition of water-soluble or water-insoluble fillers (such as lactose or microcrystalline cellulose). The floating behavior of the low density drug delivery systems could successfully be combined with accurate control of the drug release patterns.     

In vitro characterization and release study of Ambroxol hydrochloride matrix tablets prepared by direct compression

A series of either hydrophilic or hydrophobic polymers were used to prepare controlled release Ambroxol hydrochloride (AMX) matrix tablets by direct compression. Both the compatibility and flow properties of AMX/polymer mixtures were investigated. The effect of the amount and type of polymer on the physical properties and in vitro drug release was studied and compared to commercially available Ambroxol^® SR capsules. A kinetic study of the release profile of AMX from the prepared matrix tablets was performed. All excipients used in the study were compatible with the model drug. AMX/drug mixtures containing sodium alginate (NA) and hydroxypropylmethyl cellulose (HPMC) showed better flow properties than other polymers used in the study. The in vitro drug release studies showed that matrix tablets formulae containing 10% HPMC (S7) or a combination of 30% NA and 5% HPMC (Ah) exhibited a higher ability to control the release of AMX. The kinetic study revealed that a diffusion controlled mechanism prevailed except when carbopol was used. Formula Ah followed a non-fickian diffusion mechanism similar to Ambroxol^® SR capsules. Both formulae S7 and Ah could be considered as potential candidates for formulation of AMX controlled release matrix tablets.     

Effect of formulation parameters on the drug release and floating properties of gastric floating two-layer tablets with acetylsalicylic acid

Floating dosage forms of acetylsalicylic acid, used for its antithrombotic effect, were developed to prolong gastric residence time and increase bioavailability. In the two-layer tablet formulation, hydroxypropyl methylcellulose (HPMC) of high viscosity and an effervescent mixture of citric acid and sodium bicarbonate formed the floating layer. The release layer contained the drug, direct tableting agent and different types of matrix-forming polymers such as HPMC of low viscosity, sodium carboxymethylcellulose and chitosan. Tablets were prepared using a direct compression technique. The effect of formulation variables on physicochemical and floating properties and the drug release from tablets were investigated. Floating ability was dependent on the amount of effervescent agent and gel-forming polymer of the floating layer. Drug release was prolonged to 8 hours by changing the type and viscosity of the matrix-forming polymer in the drug-loading layer and all formulations showed a diffusion release mechanisms.     

卡维地洛凝胶骨架缓释片的处方优选与表征

目的 优选12 h内体外缓慢释药的卡维地洛凝胶骨架缓释片的处方工艺并进行表征。方法 以2种型号的HPMC为骨架材料,通过正交试验法,优选处方工艺并验证,考察制剂在4种介质中12 h内的体外释放度,利用X-射线衍射法和红外光谱法分析药物的存在状态。结果 最佳处方为卡维地洛7.5%,单硬脂酸甘油酯30%,HPMC K4M+E50占片重25%,HPMC K4M∶E50的比例为2∶1,乳糖占15%,硬度为3.5 kg;制剂在pH 1.2的介质中释药最快,12 h内达到90%以上,体外释药稳定（RSD<1.5%,n=3）,符合Higuchi动力学方程,属于骨架溶蚀型释药系统;药物在片中以部分晶体存在,原辅料之间没有新键生成。结论 该制备工艺简单,重复性良好,在12 h内具有良好的体外缓释特征。     

The influence of crystallization inhibition of HPMC and HPMCAS on model substance dissolution and release in swellable matrix tablets

One of the drawbacks with solid solution systems is their thermodynamic instability in solution. Considering the release of these systems from extended-release formulations, in particular swellable matrix tablets, a successful tablet formulation can be regarded as a composition able to maintain the molecular state of the poorly soluble crystalline drug through diffusion in the matrix. This may in turn provide molecular rather than particulate delivery of the substance from the matrix. In this study, the solid state and dissolution behavior of amorphous solid dispersions of a model crystalline substance, butyl paraben in HPMC and HPMCAS, was investigated. In addition, the suitability of HPMCAS as both effective solid solution carrier and as extended-release matrix forming polymer was examined. The release from all systems investigated showed extended-release capacity with a release rate similar to the rate of matrix erosion. However, a detailed study of the factors affecting the release mechanism revealed that upon hydration, the model substance crystallized in the gel layer of the HPMC-based formulation, whereas it remained in amorphous form in the HPMCAS tablets. In the case of HPMCAS formulation, this effect was attributed to (i) the ability of this polymer to keep the model substance in a supersaturated state and (ii) the very slow matrix hydration, resulting in a steep concentration gradient of the drug substance and a short diffusion path through the matrix into the dissolution bulk.     

Extended release of flurbiprofen from tromethamine-buffered HPMC hydrophilic matrix tablets

Abstract

The pH-dependent solubility of a drug can lead to pH-dependent drug release from hydrophilic matrix tablets. Adding buffer salts to the formulation to attempt to mitigate this can impair matrix hydration and negatively impact drug release. An evaluation of the buffering of hydrophilic matrix tablets containing a pH-dependent solubility weak acid drug (flurbiprofen), identified as possessing a deleterious effect on hydroxypropyl methylcellulose (HPMC) solubility, swelling and gelation, with respect to drug dissolution and the characteristics of the hydrophilic matrix gel layer in the presence of tromethamine as a buffer was undertaken. The inclusion of tromethamine as an alkalizing agent afforded pH-independent flurbiprofen release from matrices based on both HPMC 2910 (E series) and 2208 (K series), while concomitantly decreasing the apparent critical effect on dissolution mediated by this drug with respect to the early pseudo-gel layer formation and functionality. Drug release profiles were unaffected by matrix pH-changes resulting from loss of tromethamine over time, suggesting that HPMC inhibited precipitation of drug from supersaturated solution in the hydrated matrix. We propose that facilitation of diffusion-based release of potentially deleterious drugs in hydrophilic matrices may be achieved through judicious selection of a buffering species.     

The use of response surface methodology for the formulation and optimization of salbutamol sulfate hydrophilic matrix sustained release tablets

The objective of this study was to develop a hydrophilic matrix formulation with in vitro release characteristics similar to Asthalin^® tablets and that would sustain the release of salbutamol sulfate over a 12-h period. A central composite design was used as the framework for manufacturing formulations that may be used to understand the relationships between polymer levels and in vitro release characteristics. Tablets were manufactured using wet granulation with Surelease^® as the granulating fluid and different levels of Methocel^® K100M, xanthan gum, and Carbopol^® 974P as matrix-forming materials. In vitro dissolution testing was conducted using USP Apparatus 3 and samples were analyzed using a validated reversed-phase HPLC method. The results revealed that the levels and types of polymers had a significant impact on the rate of drug release from these formulations and that it was possible to optimize the levels of matrix-forming polymers to achieve the desired release characteristics. Statistical design and response surface methodology have been successfully used to understand and optimize formulation factors and interactions that impact the in vitro release characteristics of salbutamol sulfate from a potential multisource sustained release dosage form.     

In Vitro Controlled Release of Alfuzosin Hydrochloride Using HPMC-Based Matrix Tablets and Its Comparison with Marketed Product

The present study is an attempt to formulate a controlled-release matrix tablet formulation for alfuzosin hydrochloride by using low viscous hydroxy propyl methyl cellulose (HPMC K-100 and HPMC 15cps) and its comparison with marketed product. Different batches of tablets containing 10 mg of alfuzosin were prepared by direct compression technique and evaluated for their physical properties, drug content, and in vitro drug release. All the formulations had a good physical integrity, and the drug content between the batches did not vary by more than 1%. Drug release from the matrix tablets was carried out for 12 hr and showed that the release rate was not highly significant with different ratios of HPMC K-100 and HPMC15cps. Similar dissolution profiles were observed between formulation F3 and the marketed product throughout the study period. The calculated regression coefficients showed a higher r² value with zero-order kinetics and Higuchi model in all the cases. Although both the models could be applicable, zero-order kinetics seems to be better. Hence, it can be concluded that the use of low viscous hydrophilic polymer of different grades (HPMC K-100 and HPMC 15cps) can control the alfuzosin release for a period of 12 hr and was comparable to the marketed product.     

氢溴酸高乌甲素亲水凝胶骨架片的制备及体外释放

目的为了减少给药次数,方便患者,并提高镇痛效果,制备氢溴酸高乌甲素亲水凝胶骨架片,优化制剂处方,并探讨释放机制。方法以羟丙甲纤维素(HPMC)为骨架材料,乳糖、微晶纤维素(MCC)、淀粉为填充剂,硬脂酸镁为润滑剂制备氢溴酸高乌甲素骨架片,考察各因素对药物释放度的影响,筛选优化处方,并拟合讨论其释放机制。结果 HPMC的用量及分子量,微晶纤维素和硬脂酸镁的用量对药物释放有显著影响。所制缓释片无突释现象,缓释周期12 h,根据拟合方程,药物释放符合一级释放模型,其释放既有扩散,又有骨架溶蚀。结论本方法制备的氢溴酸高乌甲素缓释片工艺简单,生产成本低,且具有良好的释放性能。     

Development of gastroretentive drug delivery system for cefuroxime axetil: In vitro and in vivo evaluation in human volunteers

The objective of this investigation was to develop the cefuroxime axetil sustained-release floating tablets to prolong the gastric residence time and compare their pharmacokinetic behavior with marketed conventional tablets (Zocef). The floating tablets were developed using polymers like HPMC K4M and HPMC K100M alone, and polymer combination of HPMC K4M and Polyox WSR 303 by effervescent technique. Tablets were prepared by slugging method and evaluated for their physical characteristics, in vitro drug release, and buoyancy lag time. The best formulation (F10) was selected based on in vitro characteristics and used in vivo radiographic and bioavailability studies in healthy human volunteers. All the formulations could sustain drug release for 12 h. The dissolution profiles were subjected to various kinetic release models and it was found that the mechanism of drug release followed Peppas model. The in vivo radiographic studies revealed that the tablets remained in stomach for 225±30 min. Based on in vivo performance, the developed floating tablets showed superior bioavailability than Zocef tablet. Based on in vivo performance significant difference was observed between C_max, t_max, t_1/2, AUC_0–∞, and mean residence time of test and reference (p<0.05). The increase in relative bioavailability of test was 1.61 fold when compared to reference.     

羟丙基甲基纤维素的凝胶特性及其对曲尼司特缓释片释放行为的影响

目的：研究羟丙基甲基纤维素(HPMC)的凝胶特性及其对曲尼司特缓释片释放行为的影响。方法：采用称重法、图像法和体积测量法,研究HPMC辅料片和曲尼司特缓释片在不同pH环境中的水合度和溶胀度。结果：辅料片在SGF和SIF中的水合速率常数分别为0.897 h-1和0.681 h-1;溶胀速率常数分别为1.005 h^-1和0.713 h^-1。曲尼司特缓释片在SGF中,在0.5 h内迅速水合和溶胀,其后呈负增长;而在SIF中,重量和体积都缓慢增加,5 h后重量稍有下降,体积保持不变。结论：HPMC水凝胶的形成速度和形态与介质的pH有关,凝胶层的溶蚀速度控制药物的释放。     

Formulation development and optimization of bilayer tablets of aceclofenac

Objective: The objective of the present study was to develop bilayer tablets of aceclofenac that are characterized by initial burst drug release followed by sustained release of drug.

Methods: The fast-release layer of the bilayer tablet was formulated using microcrystaline cellulose (MCC) and HPMC K4M. The amount of HPMC E4M (X₁) and MCC (X₂) was used as independent variables for optimization of sustained release formulation applying 3² factorial design. Three dependent variables were considered: percentage of aceclofenac release at 1 h, percentage of aceclofenac release at 12 h, and time to release 50% of drug (t_50%). The composition of optimum formulation of sustained release tablets were employed to formulate double layer tablets.

Results: The results indicate that X₁ and X₂ significantly affected the release properties of aceclofenac from sustained release formulation. The double layer tablets containing fast-release layer showed an initial burst drug release of more than 30% of its drug content during first 1 h followed by sustained release of the drug for a period of 24 h.

Conclusion: The double layer tablets for aceclofenac can be successfully employed as once-a-day oral-controlled release drug delivery system characterized by initial burst release of aceclofenac for providing the loading dose of drug.     

Formulation development of Carvedilol compression coated tablet

Purpose: The aim of present research was to produce carvedilol compression coated tablet to provide biphasic drug release.

Method: A compressed coated tablet made of a sustained release core tablet and an immediate release coat tablet. Both the core and the coat contained carvedilol. The sustained release effect was achieved with polymers (HPMC K₄M and PEO WSR 205) to modulate the release of the drug. The powder blends for core and coat tablets were evaluated for angle of repose, bulk density, compressibility index, and drug content. Compressed coated tablets were evaluated for thickness, diameter, weight variation test, drug content, hardness, friability, disintegration and in vitro release studies.

Result: The powder blends showed satisfactory flow properties, compressibility, drug content and all the tablet formulations showed acceptable pharmaco-technical properties. Carvedilol contained in the fast releasing component was released within 3?min, whereas the drug in the core tablet was released at different times up to 24?h, depending on the composition of the matrix tablet. The mechanism of drug release was fickian diffusion or anomalous behavior.

Discussion: Batch F7, containing 10?mg PEO WSR 205 and 5?mg HPMC K₄M, showed maximum similarity with theoretical profile and zero order drug release kinetic.     

盐酸丁螺环酮缓释片的制备及体外释放研究

目的 :为了减少给药次数和减小药物的毒副作用 ,制备盐酸丁螺环酮缓释片。方法 :采用亲水凝胶骨架材料 (HPMC)制备该缓释片 ,并考察药物与HPMC不同比例组成、HPMC不同粘度等对该水溶性药物释放的影响。结果 :药物 /HPMC之比为影响释放过程的主要因素 ,HPMC(高粘度 )的粘度与药物释放无关 ,且该骨架片的释药与释放介质的 pH无关。 结论 :该缓释片制备工艺简单 ,缓释速率可控。     

曲尼司特缓释片的制备及其释药影响因素研究

目的 制备了曲尼司特凝胶骨架片。方法 采用HPMC K4M、K15M为凝胶骨架材料，进行了处方研究；通过测定制剂体外释放度，评价了该缓释片处方。结果 曲尼司特缓释片体外释药符合Higuchi方程，其释药速率常数Kr为0．193h^1/2。影响缓释片体外释药的因素有骨架材料的种类、用量、粘合剂的种类和释药介质的pH等。结论 缓释片具有明显的缓释作用，可缓慢释药12h。     

Release of theophylline and carbamazepine from matrix tablets - Consequences of HPMC chemical heterogeneity

The release of theophylline and carbamazepine from matrix tablets composed of microcrystalline cellulose, lactose and hydroxypropyl methylcellulose (HPMC) was studied. The aim was to investigate the effect of different substituent heterogeneities of HPMC on the drug release from matrix tablets composed of either 35% or 45% HPMC. The release of the poorly soluble carbamazepine was considerably affected by the HPMC heterogeneity, and the time difference at 80% drug release was more than 12 h between the formulations of different HPMC batches. This was explained by slower polymer erosion of the heterogeneous HPMC and the fact that carbamazepine was mainly released by erosion. In addition, results from magnetic resonance imaging showed that the rate of water transport into the tablets was similar. This explained the comparable results of the release of the sparingly soluble theophylline from the two formulations even though the polymer erosion and the swelling of the tablets were considerably different. Thus, it can be concluded that the drug release was highly affected by the substituent heterogeneity, especially in the case of carbamazepine, which was released mainly by erosion.     

Optimization of primaquine diphosphate tablet formulation for controlled drug release using the mixture experimental design

A tablet formulation based on hydrophilic matrix with a controlled drug release was developed, and the effect of polymer concentrations on the release of primaquine diphosphate was evaluated. To achieve this purpose, a 20-run, four-factor with multiple constraints on the proportions of the components was employed to obtain tablet compositions. Drug release was determined by an in vitro dissolution study in phosphate buffer solution at pH 6.8. The polynomial fitted functions described the behavior of the mixture on simplex coordinate systems to study the effects of each factor (polymer) on tablet characteristics. Based on the response surface methodology, a tablet composition was optimized with the purpose of obtaining a primaquine diphosphate release closer to a zero order kinetic. This formulation released 85.22% of the drug for 8 h and its kinetic was studied regarding to Korsmeyer–Peppas model, (Adj-R² = 0.99295) which has confirmed that both diffusion and erosion were related to the mechanism of the drug release. The data from the optimized formulation were very close to the predictions from statistical analysis, demonstrating that mixture experimental design could be used to optimize primaquine diphosphate dissolution from hidroxypropylmethyl cellulose and polyethylene glycol matrix tablets.     

Relationship Between Gelation Rate of Controlled-release Acetaminophen Tablets Containing Polyethylene Oxide and Colonic Drug Release in Dogs

Purpose. We hypothesized that sufficient gelation of orally administered hydrophilic matrix tablets before they reach the colon could, as a result of continuous erosion of the gelated matrix, prevent the decrease in colonic drug release which normally occurs here. The purpose of this study was to elucidate the effect of gelation of hydrophilic matrices containing polyethylene oxide on colonic drug release in dogs using controlled-release (CR) acetaminophen tablets. Methods. Two types of CR tablets were prepared, a slow gelling tablet (SG) and a rapid gelling tablet (RG) containing an extra highly water soluble filler. In vitro and in vivo performance were examined. Results. SG and RG showed similar drug release behavior in vitro. In oral administration to dogs, the two formulations showed similar gastrointestinal transit, reaching the colon within 2–4 h after oral dosing. Further, they showed similar maximum plasma levels (Cmax) and time to Cmax (Tmax). In contrast, however, the two tablets produced different plasma levels from 2 h post-dosing, with plasma levels of RG higher than those of SG and with smaller individual variation. Directly observed colonic drug release behavior of RG was similar to in vitro drug release, whereas that from SG was suppressed. Conclusions. Colonic drug release is closely related to the gelation of hydrophilic matrix, and rapid gelation provides continuous in vivo drug release.