布洛芬HPMC骨架片药物释放因素研究

目的 考察影响布洛芬亲水性骨架片体外释药的各种因素。方法 以羟丙基甲基纤维素（HPMC）为骨架材料，用湿法制粒和粉末直接压片法制备缓释骨架片，并考察HPMC用量，粒度，制备方法，片子大小及其它辅料对布洛芬HPMC骨架片的体外释药的影响。结果 布洛芬HPMC骨架片的体外释药均符合Higuchi方程。HPMC的用量，粒度和制法，片子大小对布洛芬的释放速率均有显著影响。湿法制片的释药速率比干法慢。布洛共姝释药速率随HPMC粒度的减小和片子的增大而减慢。淀粉，PVP、MCC、EC的加入（每片HPMC的含量不变）均减慢布洛芬释药速率。结论 HPMC用量、粒度、制备方法、片子大小及其它辅料为布洛芬骨架片释放速率的主要因素。     

盐酸二甲双胍渗透泵控释片的制备及体外释放度考察

目的研究盐酸二甲双胍渗透泵控释片的制备工艺及体外释药的影响因素。方法通过单因素考察和正交试验,优化制备工艺。结果盐酸二甲双胍渗透泵控释片的体外释药符合零级释放规律,释药速率受PEG种类、PEG用量、包衣膜重量影响较大,在一定范围内,释药孔大小、片芯硬度、溶出介质pH值和桨转速对其影响较小。结论盐酸二甲双胍渗透泵控释片工艺稳定,能够达到9h明显的恒速释药。     

阿奇霉素缓释微丸体外释药影响因素考察

考察影响阿奇霉素缓释微丸体外释药的各种因素,为阿奇霉素缓释制剂的研制提供实验依据。方法选用微晶纤维素为空白丸芯,将阿奇霉素制成缓释微丸,通过测定体外释放度,考察EC粘度及增重、致孔剂用量、释放介质pH值对阿奇霉素缓释微丸体外释药速率的影响。结果 EC粘度、包衣增重、致孔剂用量、释放介质pH值对释药速率有显著影响。结论选用适宜包衣材料及致孔剂,调节包衣增重,可制备具有理想释药行为的阿奇霉素缓释微丸。     

夏天无总生物碱阳离子树脂复合物的体外释放特性

目的制备夏天无总生物碱树脂复合物并对其指标性成分进行体外释药动力学考察。方法静态交换法制备夏天无总生物碱树脂复合物,以原阿片碱、延胡索乙素为指标性成分,对夏天无总生物碱树脂复合物在不同温度(37、45℃)、不同离子强度释放介质(去离子水、0.15 mol.L-1NaCl、0.6 mo.lL-1NaCl)、不同反离子溶液(0.15 mo.lL-1NaCl、0.15 mol.L-1KCl、0.15 mol.L-1盐酸)中的释药动力学进行了考察。结果体外释药动力学表明,夏天无总生物碱树脂复合物中原阿片碱和延胡索乙素的释药速率随温度的升高而加快,随溶出介质中的离子强度的增大而增大,且释药速率随反离子离子半径增大而减慢(K+相似文献   

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。     

磷酸川芎嗪丙烯酸树脂水分散体包衣小丸的体外释放研究

目的：研究磷酸川芎嗪丙烯酸树脂水分散体包衣缓释小丸的体外释药。方法：采用丙烯酸树脂RS30D和丙烯酸树脂RL30D混合液包衣制备磷酸川芎嗪缓释小丸，并考察包衣混合液中两种丙烯酸树脂水分散体比例、包衣增重、溶出介质pH对磷酸川芎嗪包衣制剂体外释药的影响。结果：随着包衣液中丙烯酸树脂RL30D/丙烯酸树脂RS30D比例增大、包衣增重降低、溶出介质pH增大，释药速率加快。结论：包衣液中丙烯酸树脂RL30D/丙烯酸树脂RS30D比例、包衣增重、溶出介质pH均显著影响制剂药物释放。     

阿奇霉素缓释微丸体外释药影响因素考察

目的 考察影响阿奇霉素缓释微丸体外释药的各种因素,为阿奇霉素缓释制剂的研制提供实验依据。方法 选用微晶纤维素为空白丸芯,将阿奇霉素制成缓释微丸,通过测定体外释放度,考察EC粘度及增重、致孔剂用量、释放介质pH值对阿奇霉素缓释微丸体外释药速率的影响。结果 EC粘度、包衣增重、致孔剂用量、释放介质pH值对释药速率有显著影响。结论 选用适宜包衣材料及致孔剂,调节包衣增重,可制备具有理想释药行为的阿奇霉素缓释微丸。     

吲哚拉辛HPMC骨架片药物释放因素研究

目的 考察影响吲哚拉辛亲水性骨架片体外释药的各种因素。方法 以羟丙基甲基纤维素（HPMC）为骨架材料,用湿法制粒和粉末直接压片法制备缓释骨架片,并考察HPMC用量、粒度、制备方法、片子大小及其它辅料对吲哚拉辛HPMC骨架片的体外释药的影响。结果 吲哚拉辛HPMC骨架片的体外释药均符合Higuchi方程。HPMC的用量,粒度和制法,片子大小对吲哚拉辛的释放速率随HPMC粒度和片子的减小而减慢。淀粉、PVP、MCC的加入（每片HPMC的含量不变）均加快吲哚拉辛释药速率,且加入量不同,其释药速率问具有显著性差异。随着EC加入量的增加（≥40mg。片^-1）．吲哚拉辛释放速率显著加快。结论 HPMC用量和粒度、制备方法、片子大小及其它辅料为影响吲哚拉辛骨架片释放速率主要因素。     

硫酸特布他林脉冲控释片的制备与释放机理研究硫酸特布他林脉冲控释片的制备与释放机理研究

目的制备硫酸特布他林双层包衣脉冲片，考察处方及释放条件对体外释药行为的影响，解析其释放机理。方法粉末直接压片法制备含渗透活性物质的片芯，滚转包衣锅法分别包溶胀层和控释衣层。通过测定释放度研究脉冲片的制剂学特征，并研究脉冲片的吸水动力学和膨胀行为。结果双层包衣片以脉冲形式释放，释药时滞随控释衣层厚度增加而延长，释药速度减小；渗透活性物质和溶胀层可提高快速释放期的释药速率。溶出介质pH值和搅拌速度对释药行为无影响。释药机理包括扩散、溶胀和渗透泵原理。结论调整控释衣膜厚度和组成可获得理想的脉冲释药行为，满足时辰治疗的要求。     

烟酸缓释片的研制及其释药特性的研究

目的:制备烟酸缓释片,并对其释药性质进行了研究.方法:分别采用不同粒度烟酸和不同粒度、粘度、含量的羟丙甲纤维素以及不同压力的方法制备烟酸缓释片,在不同pH值释放介质中测定其释放度,并与国外同类缓释片进行比较.结果:HPMC的粒度、粘度、压片压力对本制剂的释药影响不大.随着烟酸粒度的减小,HPMC用量的增加和释放介质的pH值增高,释药速率减慢.结论:烟酸缓释片的释药过程符合Higuchi方程,影响药物释放的主要因素是烟酸的粒度、HPMC的用量和释放介质的pH值;研制的烟酸缓释片与国外样品体外释放速率相近.     

Development of controlled release oral drug delivery system by membrane-coating method-I

In order to develop a controlled-release oral drug delivery system (DDS) which sustains the plasma acetaminophen (AAP) concentration for a certain period of time, microporous membrane-coated tablets were prepared and evaluatedin vitro. Firstly, highly water-soluble core tablets of AAP were prepared with various formulations by wet granulation and compression technique. Then the core tablets were coated with polyvinylchloride (PVC) in which micronized sucrose particles were dispersed. Effect of formula compositions of core tablets and coating suspensions on the pharmaceutical characteristics such as drug release kinetics and membrane stability of the coated tablets was investigatedin vitro. AAP was released from the coated tablets at a zero-order rate in a pH-independent manner. This independency of AAP release to pH change from 1.2 to 7.2 is favorable for the controlled oral drug delivery, since it will produce a constant drug release in the stomach and intestine regardless of the pH change in the GI tract. Drug release could be extended upto 10 h according to the coating condition. The release rate could be controlled by changing the formula compositions of the core tablets and coating suspensions, coat weight per each tablet, and especially PVC/sucrose ratio and particle size of the sucrose in the coating suspension. The coated tablets prepared in this study had a fairly good pharmaceutical characteristicsin vitro, however, overall evaluation of the coated tablets should awaitin vivo absorption study in man.     

Preparation and evaluation of slow-release pan-coated indomethacin granules

Abstract

Granules containing indomethacin crystals are coated with Eudragit solutions of different RL/RS ratios using a pan coating technique. The process is reproducible with regard to drug content, inexpensive and the formed granules were directly compressed into tablets. In vitro release of indomethacin from coated granules, tablets and capsules was studied as a function of different ratios of Eudragit RL/RS in the coating solution. The release of the drug was significantly reduced by the coating process in comparison with a formulation made from uncoated granules, prepared using 10 per cent gelatin solution as a binder. Release data were found to follow a diffusion-controlled model.     

Novel method for the preparation of controlled-release theophylline granules coated with a polyelectrolyte complex of sodium polyphosphate-chitosan

A novel method for the preparation of theophylline granules coated with a polyelectrolyte complex of sodium tripolyphosphate and chitosan was developed. The theophylline granules containing sodium tripolyphosphate were stirred in an HCl solution of chitosan. During the mixing, the dissolved sodium tripolyphosphate in the granule moved to the surface and reacted with the chitosan, resulting in the formation of the polyelectrolyte complex film. The factors affecting the drug content, the particle size, and the coating-film thickness of the resultant coated granules were determined. The theophylline content in the coated granule decreased with increasing content ratio of sodium tripolyphosphate to theophylline in the original granule and with increasing chitosan concentration in the coating solution. The coated granule size increased with increasing chitosan concentration in the coating solution and with decreasing agitation speed. The coating-film thickness increased with an increase in the chitosan concentration, the pH of the coating solution, and the sodium tripolyphosphate to theophylline content ratio in the original granule. The drug-release pattern of the coated granules followed zero-order kinetics and the release rates were significantly reduced compared with that of the original granule.     

pH triggered delivery of curcumin from Eudragit-coated chitosan microspheres for inflammatory bowel disease: characterization and pharmacodynamic evaluation

Objective: This investigation deals with the development and evaluation (in vitro and in vivo) of pH triggered Eudragit-coated chitosan microspheres of curcumin (CUR) for treating ulcerative colitis.

Methods: CUR-loaded chitosan microspheres were initially prepared by emulsion cross linking method followed by coating with Eudragit S-100. The pharmacodynamics of the developed formulation was analyzed in mice by acetic acid induced colitis model.

Results: The developed microspheres were of uniform spherical shape with high entrapment efficiency. CUR-chitosan microspheres showed less intense peaks compared to free CUR confirming inclusion of drug within microspheres as revealed by X-ray diffractogram. Uncoated CUR-chitosan microspheres exhibited burst release within initial 4?h while microspheres coated with Eudragit S-100 prevented premature release of CUR and showed controlled release up to 12?h following Higuchi model. In vivo organ biodistribution study showed negligible amount of CUR in stomach and small intestine confirming integrity of microsphere in upper gastrointestinal tract (GIT). In vivo study revealed significant reduction in severity and extent of colonic damage with CUR-loaded microspheres as compared to pure CUR which was further confirmed by histopathological study.

Conclusion: In vitro and in vivo studies proved the developed formulations as a promising system for pH-dependent delivery of drug to colon in ulcerative colitis.     

In Vivo/in Vitro Correlation of Experimental Sustained-Release Theophylline Formulations

A novel multiparticulate sustained-release theophylline formulation, which consisted of spherical drug pellets coated with a rate-controlling membrane, was evaluated in vivo. Two preparations that differ solely in the coat thickness, and hence rate of in vitro drug release, were studied in comparison with a solution of the drug. Both preparations produced serum concentration profiles that are reflective of a slow and sustained rate of absorption. The in vivo release versus time profiles calculated using a deconvolution procedure showed that the two preparations differed in the rate but not the extent of drug release. Satisfactory correlation was also obtained between the in vivo and the in vitro results. When the two preparations were further compared using the parameters, time to reach peak concentration (T _p), peak concentration (C _p), and total area under the serum concentration versus time curves (AUC), a statistically significant difference was observed in the T _p and C _p values but not the AUC values, suggesting that the preparations differed in the rate but not the extent of absorption. In addition, the extent of absorption from both preparations was comparable to that obtained with the drug solution.     

Development and in Vitro-in Vivo Evaluation of a Multiparticulate Sustained Release Formulation of Diltiazem

Purpose. To develop and evaluate the in vitro/in vivo performance of diltiazem sustained release pellets that were prepared by the Wurster column process. Methods. Pellets containing diltiazem were prepared by spraying a slurry of micronized diltiazem hydrochloride, pharmaceutical glaze and alcohol onto an appropriate mesh fraction of nonpareil seeds using the Wurster column. A two-step drug layering process was used to increase drug loading from 60% to 75%. The oven-dried diltiazem basic pellets were coated with eth-ylcellulose/dibutyl sebacate coating solution to yield diltiazem sustained release pellets. An open, randomized Latin square, three-way crossover clinical study was used to evaluate the in vivo performance of the coated product. Results. Altering the mesh fraction of the starting nonpareil seeds for this layering process was found to affect the release characteristics of drug from the pellets. An oven-drying step was required to stabilize the diltiazem basic pellets. The thicker the drug loading layer the longer the oven drying is needed to stabilize the pellets. The diltiazem sustained release pellets produced by these methods displayed sustained release dissolution profiles both in vitro and in vivo. Diltiazem basic pellets coated with a 0.6% ethylcellulose/dibutyl sebacate coating showed a different rate of absorption (lower C _max and higherT _max) and the same extent of absorption as compared to Cardizem^® tablets. Conclusions. Clinical data confirmed that this formulation approach is an effective means to produce a diltiazem sustained release product.     

Effect of Destruction Force on Drug Release from Multiple Unit Controlled Release Dosage Forms in Humans

Purpose. This study examined the effects of mechanical destructive forces on drug release from controlled release (CR) multiple unit dosage forms in vitro and in vivo and their colonic release, using two CR granules of acetaminophen, AG and BG, which differed in hardness (AG was hard and BG was soft), but which did not depend on agitation speed or pH for their release. Methods. In vitro release rates were determined using several official methods and the rotating dialysis cell method. Granules were administered to healthy volunteers under fasting and fed conditions. Results. Both granules showed similar release rates under mild destructive conditions in official dissolution tests, but BG showed a faster release rate in the rotating dialysis cell method. In the fasting state, the drug absorption-time profiles of AG and BG were almost equal. In the fed state, the drug release rate of BG increases whereas that of AG is almost equal to the fasted state. The food effect on BG could be caused by an increase in the mechanical stress of the GI tract due to food intake judging from the findings in vitro and in dogs. The colonic release from multiple unit CR products was larger than that from single unit ones. Conclusions. In vivo release of drug from a multiple unit CR product that is structurally weak is affected by mechanical stresses, which differ among human subjects but are increased by food ingestion. Colonic release from multiple unit CR products is larger than that from single unit products.     

Development and characterization of polymer-coated liposomes for vaginal delivery of sildenafil citrate

Vaginal administration of sildenafil citrate has shown recently to develop efficiently the uterine lining with subsequent successful embryo implantation following in vitro fertilization. The aim of the present study was to develop sildenafil-loaded liposomes coated with bioadhesive polymers for enhanced vaginal retention and improved drug permeation. Three liposomal formulae were prepared by thin-film method using different phospholipid:cholesterol ratios. The optimal liposomal formulation was coated with bioadhesive polymers (chitosan and HPMC). A marked increase in liposomal size and zeta potential was observed for all coated liposomal formulations. HPMC-coated liposomes showed the greater bioadhesion and higher entrapment efficiency than chitosan-coated formulae. The in vitro release studies showed prolonged release of sildenafil from coated liposomes as compared to uncoated liposomes and sildenafil solution. Ex vivo permeation study revealed the enhanced permeation of coated relative to uncoated liposomes. Chitosan-coated formula demonstrated highest drug permeation and was thus selected for further investigations. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) confirmed the successful coating of the liposomes by chitosan. Histopathological in vivo testing proved the efficacy of chitosan-coated liposomes to improve blood flow to the vaginal endometrium and to increase endometrial thickness. Chitosan-coated liposomes can be considered as potential novel drug delivery system intended for the vaginal administration of sildenafil, which would prolong system's retention at the vaginal site and enhance the permeation of sildenafil to uterine blood circulation.     

<Emphasis Type="Italic">In vitro</Emphasis> and <Emphasis Type="Italic">in vivo</Emphasis> evaluations of ketoprofen extended release pellets prepared using powder layering technique in a rotary centrifugal granulator

In the present study, an extended release pellet dosage form of ketoprofen was prepared using powder layering technique. A combination of ethyl cellulose (45 cps) and shellac polymers was used as a binder (12% w/w polymer) during drug layering and an extended release coating (1:3 ratio at 2%, 4% and 7% w/w polymer) within the same apparatus. The coated pellets were characterized for sphericity, Hardness-Friability Index, and drug content, and also underwent scanning electron microscopy. In vitro dissolution was performed in 900 mL of phosphate buffer (pH 6.8) using paddle apparatus at 100 rpm. Ethyl cellulose and shellac when used as binders during drug loading did not extend ketoprofen release beyond 3 h. However, coating of the drug loaded pellets using ethyl cellulose and shellac resulted in an extended release profile of about 10 h. Using Higuchi’s model and the Korsmeyer equation, the drug release mechanism from the pellets was found to be an anomalous type involving diffusion and erosion. Scanning electron microscopy was used to visualize the pellet morphology and drug release mechanism during dissolution testing. In vivo evaluations of the extended release pellets in rats indicated a significant increase in the time to reach maximum concentration (t_max) and extent of absorption (AUC_0-∞) compared to the ketoprofen immediate release tablet blend dispersed and dosed. In conclusion, extended release pellets of ketoprofen could perform therapeutically better than conventional dosage forms, leading to improved efficacy for a prolonged period.     

Effect of Colonic Lactulose Availability on the Timing of Drug Release Onset in Vivo from a Unique Colon-Specific Drug Delivery System (CODES™)

Purpose. To test the hypothesis that the onset of drug release in vivo from a unique colon-specific drug delivery system (CODES) would depend on the colonic availability rate of lactulose. The site specificity of drug release in canine GI tract was also estimated. Methods. CODES tablets were prepared by tableting the granulation of acetaminophen and lactulose, followed with film coating. The pharmacokinetic performance of different CODES formulations was evaluated in six beagle dogs under fasted conditions. The release of acetaminophen and lactulose was also characterized in vitro. Results. The onset of acetaminophen release in beagle dogs was found to be dependent on the coating level of Eudragit E and lactulose loading in the core tablet. At Eudragit E coating levels of 4%, 8%, and 12% (coating weight gain), the onset of in vivo drug release occurred 5.5 (±1.9) h, 4.8 (±1.0) h. and 7.5 (±1.0) h, respectively, after dosing. A similar trend was observed when the loading of lactulose in the core tablet decreased from 78% to 58% and 38%. However, the rate and extent of acetaminophen absorption did not vary significantly in each situation based on the values of AUC and C_max. Conclusions. The onset of drug release in vivo from CODES tablets is predominantly dependent on colonic availability rate of lactulose because drug release from this system is triggered by localized drop of colonic pH from the fermentation of lactulose.