Physicochemical characterization and dissolution enhancement of aceclofenac-hydroxypropyl beta-cyclodextrin binary systems

The aim of this study is to prepare and characterize binary systems of aceclofenac (AC) with hydroxypropyl beta-cyclodextrin (HPbetaCD) in equimolar ratio. Solid binary systems of aceclofenac with HPbetaCD were prepared using cogrinding, kneading, and coevaporating methods, and a physical mixture was prepared for comparison. The binary systems were characterized by differential scanning calorimetry, thermogravimetric analysis, mass spectroscopy, 1H nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy, and in vitro dissolution studies. 1H NMR studies showed that AC partially fits into the HPbetaCD torus cavity with a preferential inclusion of the phenyl ring of the drug. All the binary systems showed superior dissolution and lower dose:solubility ratio (D:S ratio) as compared to pure AC, but the kneaded product exhibited the best dissolution, with complete drug release within 10 min and a D:S ratio of 5 mL. Hence, it was suggested that complexation of aceclofenac with HPbetaCD may be used as an approach to change the drug from Biopharmaceutics Classification System BCS Class II to BCS Class I without changing its intrinsic permeability.     

硝苯地平片剂溶出度的考察

目的考察不同生产企业生产的硝苯地平片剂的体外溶出度。方法分别以0.1 mol.L-1盐酸溶液、人工胃液(不含胃蛋白酶)、pH 4.5醋酸钠缓冲液、pH 6.8磷酸盐缓冲液和蒸馏水为溶出介质,采用紫外分光光度法检查;以质量分数为0.25%十二烷基硫酸钠为溶出介质,采用HPLC法检查,比较不同厂家硝苯地平片剂的体外溶出度。用相似因子法评价硝苯地平片剂在0.1 mol.L-1盐酸溶液、人工胃液(不含胃蛋白酶)、pH 4.5醋酸钠缓冲液、pH 6.8磷酸盐缓冲液和蒸馏水中的溶出行为。结果在质量分数为0.25%十二烷基硫酸钠溶液中,硝苯地平的溶出度在60 min均大于65%,而在其他溶出介质中的溶出度均达不到《英国药典》及《美国药典》中规定的标准。相似因子f2均在50~100之间。结论溶出介质的pH值对硝苯地平的溶出度没有影响。从整体来看,国产硝苯地平片剂的体外溶出行为与国外制剂相比有很大差距。     

Physicochemical characterization and dissolution properties of meloxicam-gelucire 50/13 binary systems

A solid dispersion of Meloxicam (MX), a poorly soluble, non steroidal anti-inflammatory drug, and Gelucire 50/13 was prepared by spray drying. Spherical microparticles were yielded with smooth surfaces as observed by scanning electron microscopy. According to differential scanning calorimetry and powder X-ray diffractometry analysis, MX was transformed from the crystalline state to the amorphous state as confirmed by the disappearance of its melting peak and the crystalline peaks. The dissolution tests at pH 7.4 revealed that the dissolution rate of encapsulated MX was 2.5-fold higher than that of the corresponding physical mixture and fourfold higher than the drug alone, respectively. The microparticles prepared at a ratio of 1:4 (drug/Gelucire) exhibited a 4-fold higher anti-inflammatory activity on the paw edema of rats in comparison to the drug alone. All in all, this work reveals that spray drying is a suitable technique for preparation of solid dispersions with improved biopharmaceutical and pharmacological characteristics of MX.     

以泊洛沙姆188或聚乙二醇8000为载体制备槲皮素晶体分散体系的表征及体外溶出行为研究

目的 制备不同高分子材料的槲皮素（QUR）结晶固体分散体（QUR-CSD）,探讨高分子材料对QUR-CSD体外溶出行为的影响及其可能的分子机制。方法 分别以泊洛沙姆188（P188）或聚乙二醇8000（PEG8000）为载体,QUR为模型药物,采用旋转蒸发法制备2种QUR-CSD（CSD-P188-QUR、CSD-PEG-QUR）。扫描电子显微镜（SEM）观察样品的微观结构;粉末X-射线衍射法（PXRD）观察晶体学特性;差示扫描量热法（DSC）测定起始熔融温度（T_c,onset）;通过粉末溶出、本征溶出、片剂pH转换溶出实验考察体外溶出行为。结果 CSD表征结果显示,2种QUR-CSD中QUR均以结晶态存在,晶体粒径、晶畴尺寸和结晶度均较原料药有所减小,且以P188为载体的CSD对药物上述性质的影响更明显。3种不同的体外溶出实验结果均显示CSD-P188-QUR溶出行为最佳,其次是CSD-PEG-QUR,QUR最差。结论 2种高分子材料均可通过影响CSD中QUR的微观结构来改善其体外溶出行为,且以P188为载体的CSD对药物微观结构的影响更为显著。     

不同厂家硝苯地平控释片体外溶出度的比较

目的:考察不同厂家硝苯地平控释片的质量,并为临床用药提供可靠的指导性依据。方法:参考中国药典2005版溶出度测定法的条件,以人工胃液为溶出介质进行四种硝苯地平控释片的体外溶出试验,采用UV吸收光谱法测定样品液的浓度,计算累积溶出量。结果:不同厂家药物的溶出度之间存在显著差异。结论:与国外样品相比,B样品与C样品的控释效果较好;A样品的控释效果较差.说明B样品与C样品的制剂已达到国外先进水平,A样品需要改进其制剂工艺。     

Characterization of nifedipine solid dispersions

The sublingual administration of nifedipine (NIF) is currently used in clinical practice. The sublingual administration of NIF solid dispersions (SD), by using a suitable dispenser, appears an interesting approach in the treatment of moderate and severe hypertensive emergencies. With this aim nine SD made of NIF and a low viscosity hydroxypropylmethylcellulose (HPMC) in different ratio were prepared by means of spray-drying technique and their structure was studied. Moreover, the drug dissolution properties from SD were verified. The characteristic peaks of crystalline NIF were not detectable by using the X-ray analysis when the NIF/HPMC ratios were lower than 50/50 w/w. In thermograms obtained from SD, the NIF melting endothermic peak disappeared when NIF/HPMC ratios were lower than 30/70 w/w; the experimental Tg values of SD were lower than the Tg values predicted by Gordon Taylor equation suggesting some type of non-ideality of mixing. In the SD FTIR spectra the NH stretching vibrations and the C=O stretch in esteric groups of NIF shift to free NH and C=O regions indicating the rupture of intermolecular hydrogen bond in the crystalline structure of NIF. The prepared SD improved the NIF dissolution rate in comparison with that of commercial NIF or NIF/HPMC physical mixtures. Moreover, the concentration of NIF in the dissolution medium increased decreasing the NIF content.     

Preparation and characterization of nanocrystals for solubility and dissolution rate enhancement of nifedipine

Poorly water-soluble drugs such as nifedipine (NIF) (approximately 20 microg/ml) offer challenging problems in drug formulation as poor solubility is generally associated to poor dissolution characteristics and thus to poor oral bioavailability. In order to enhance these characteristics, preparation of nifedipine nanoparticles has been achieved using high pressure homogenization. The homogenization procedure has first been optimized in regard to particle size and size distribution. Nanoparticles were characterized in terms of size, morphology and redispersion characteristics following water-removal. Saturation solubility and dissolution characteristics were investigated and compared to the un-milled commercial NIF to verify the theoretical hypothesis on the benefit of increased surface area. Crystalline state evaluation before and following particle size reduction was also conducted through differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) to denote eventual transformation to amorphous state during the homogenization process. Through this study, it has been shown that initial crystalline state is maintained following particle size reduction and that the dissolution characteristics of nifedipine nanoparticles were significantly increased in regards to the commercial product. The method being simple and easily scaled up, this approach should have a general applicability to many poorly water-soluble drug entities.     

Intraoralia containing gelatin--a dissolution model and means of influencing dissolution behavior

A dissolution model was developed especially for the study of Intraoralia containing Gelatin and used to determine the dissolution behaviour of disc-shaped pieces of Gelatin of different composition (addition of a plasticizer and Formaldehyde) by means of the electrical conductance.     

应用光纤药物溶出仪对硝苯地平缓释片释放度的考察

目的:对硝苯地平缓释片进行全程的实时、原位在线释放度测定,并与该品种已有国标[1]释放度测定结果进行比较.方法:运用FODT-601光纤药物溶出仪,选择237/550 nm双波长法,消除赋形剂干扰,按该品种已有国标释放度检查项溶出条件,测试该药物溶出曲线,并与按国标方法测得的溶出曲线进行比较.结果:在3.37μg·mL-1～17.83μg·mL-1范围内,浓度(C)与吸光度(A)呈良好的线性关系,浓度对应的溶出量(Q)% 与吸光度(A)也呈良好的线性关系,相关系数均在0.9990以上;3个浓度各3份样在6个通道的平均回收率分别为98.52%、99.22%、98.78%;对应的RSD(n=18)分别为1.1%、0.7%、0.7%,溶出曲线与国标方法测定的溶出曲线无显著性差异(P>0.05).结论:硝苯地平缓释片光纤药物溶出仪测定结果与按常规国标方法测定结果基本一致,而且该法具有操作简便,测定快速,获取信息量更大的优点.     

Comparison of dissolution profiles obtained from nifedipine extended release once a day products using different dissolution test apparatuses

In order to improve the predictability of dissolution testing new apparatuses have been proposed that mimic hydrodynamic and mechanical conditions in the gastrointestinal tract. In this study tested were four different nifedipine extended release (ER) formulations using the paddle apparatus and the reciprocating cylinder as pharmacopoeial test devices as well as two newly developed test apparatuses: the rotating beaker apparatus and the dissolution stress test apparatus. Investigated were Adalat OROS in strengths of 30 and 60 mg, and two hydrophilic matrix formulations: 60 mg nifedipine Coral and Nifedipin Sandoz 40 mg retard. The results demonstrate that the dissolution characteristic of the ER tablets is strongly dependent on the applied test conditions. The dosage form related food effects for Coral 60 mg tablets that were previously observed in human bioequivalence studies could be predicted with the two non-compendial dissolution test devices. The dissolution of Sandoz 40 mg tablets was very sensitive to all applied test conditions. The stable drug delivery characteristics of Adalat OROS observed in numerous in vivo studies was also observed in all of the dissolution tests. In conclusion, the present study shows that besides pH dependency the aspect of the mechanical robustness may be an essential factor affecting the dissolution characteristic of hydrogel matrix formulations.     

Ultrasound-compacted indomethacin/polyvinylpyrrolidone systems: effect of compaction process on particle morphology and dissolution behavior

Indomethacin (IMC)/polyvinylpyrrolidone systems were prepared under different technological conditions, using co-evaporation, kneading, traditional, and ultrasound (US) compaction. The materials thus obtained were milled and sieved and the powders were analyzed by using scanning electron microscopy to evaluate the morphology of the final particles and the fractal dimension of the particle contour. In the case of US-treated particles, scanning electron micrographs suggest that IMC could have partially covered the excipient granule surface, which appears lustrous and smooth, whereas after co-evaporation, the particles display a stratified structure. The external color of the granules, the hot stage microscopy examination, and the absence of the melting peak of the drug in thermograms supports the idea that IMC converts into an amorphous form under US discharge. Each technological treatment performed on the binary mixtures increases the dissolution rate of the drug, with respect to the pure drug and the physical mixture, but to a lesser extent than US compaction. US compaction and co-evaporation produce comparable results in improving the release of the drug. Polyvinylpyrrolidone offers better results than beta-cyclodextrin in promoting the dissolution of IMC, when both systems are compacted under US.     

硝苯地平片体外溶出特性的研究

目的：提高硝苯地平片的体外溶出速率。方法：分别考察药物粒度、稀释剂、崩解剂对体外溶出度的影响，比较溶出特性曲线筛选处方。结果：用优选处方制备的硝苯地平片溶出良好，达到中国药典2000版规定。结论：该片剂处方合理，制备工艺简单易行，适合工业化生产。     

Bioavailability and dissolution behavior of trisulfapyrimidine suspensions.

The bioavailability of seven commercial trisulfapyrimidine suspensions was studied in 14 adult male volunteers. Fifteen blood samples were collected over a 48-hr period following administration of a 1-g dose of each suspension. Serum was assayed for each component (sulfadiazine, sulfamerazine, and sulfamethazine) by high-pressure liquid chromatography. Analysis of variance indicated several significant differences among the seven commercial preparations with respect to Cmax Tmax, and AUC for sulfadiazine, sulfamerazine, and sulfamethazine, The in vitro behavior of each suspension was then studied by the paddle method of the Food and Drug Administration. A 0.5-ml sample was introduced into 900 ml of hydrochloric acid (2.2 x 10(-4) M) at 37 degree and dissolved using a paddle speed of 25 rpm. Samples withdrawn at 15 and 30 min were analyzed by high-pressure liquid chromatography, and the percent of sulfadiazine, sulfamerazine, and sulfamethazine was calculated. Significant correlation was obtained between an in vivo parameter (Cmax for sulfadiazine) and an in vitro parameter (percent sulfadiazine dissolved in 30 min). Results indicate that this method is suitable for the in vitro screening of trisulapyrimidine suspensions.     

Simultaneous solubility and dissolution rate of sulfamethoxazole and trimethoprim in binary mixture

The solubilities of trimethoprim in solutions with different pH values decreased in the presence of sulfamethoxazole, while that of the latter increased in the presence of the first. The dissolution rate of trimethoprim in HCl (0.1 mol/1) was the same in the presence and absence of sulfamethoxazole. That of sulfamethoxazole however, decreased in the presence of trimethoprim. The different reasons were explained.     

不同厂家生产的硝苯地平片体外溶出度的比较

目的：比较国内不同厂家生产的硝苯地平片的体外溶出度。方法：以紫外分光光度法测定硝苯地平的含量,分别根据《英国药典》2010年版、《美国药典》第34版和《中华人民共和国药典》2010年版的方法,对5个厂家生产的硝苯地平片的溶出度进行考察,并比较硝苯地平片在水、pH4.5乙酸钠缓冲液以及pH6.8磷酸盐缓冲液中的溶出度。运用相似因子f2法,比较硝苯地平片在不同溶出介质中溶出曲线的相似性。结果：5个厂家生产的硝苯地平片的溶出度按《中华人民共和国药典》2010年版方法测定,在60min时均〉75%;按《英国药典》2010年版方法测定,45min时均〈75%;按《美国药典》第34版方法测定,20min时均〈80%。以0.1mol/L盐酸溶液为对照,硝苯地平片在人工胃液（不含胃蛋白酶）、水、pH4.5乙酸钠缓冲液和pH6.8磷酸盐缓冲液中的溶出曲线的相似因子f2为50.93～77.45;以0.25%十二烷基硫酸钠溶液为对照,相似因子f2远〈50,表明溶出曲线不相似。结论：5个厂家生产的硝苯地平片的体外溶出度符合《中华人民共和国药典》的要求,但达不到《英国药典》和《美国药典》的标准。国内厂家生产的硝苯地平片溶出度检查标准有待提高。     

Characterization and physical stability of fast-dissolving microparticles containing nifedipine.

The suitability of a poly(sodium methacrylate, methyl methacrylate) (NaPMM), a novel mucoadhesive material, to prepare fast-dissolving microparticles containing nifedipine (NIF) in the range of 25-75% w/w was verified. Microparticles made of a low-viscosity hydroxypropylmethylcellulose (HPMC), were also prepared to compare the NIF release profile and bioadhesive properties. The release test was carried out in oversaturation conditions. The physical state of microparticles was also investigated. The formulation stability was evaluated over a 3-month period in long-term and accelerated conditions. The presence of amorphous NIF within freshly prepared microparticles was attributed to interactions between the drug and both polymers. NaPMM conferred to microparticles suitable mucoadhesive properties and significantly increased NIF dissolution rate in comparison to HPMC. Nevertheless, NIF apparent solubilities obtained by NaPMM microparticles were lower than those obtained by the HPMC set. After 3-month storage in the case of HPMC microparticles, NIF dissolution rate and supersaturation degree significantly decreased due to drug crystallization. As far as NaPMM microparticles are concerned, neither NIF dissolution rate nor apparent solubility significantly changed.     

枸橼酸他莫昔芬片在不同溶出介质中的溶出行为比较

目的使用光纤药物溶出度实时测定仪在四种不同溶出介质中测定国内2个厂家枸橼酸他莫昔芬片的体外溶出度曲线。方法测定波长275 nm、基准校正波长550 nm、温度37℃、转速100 r.min-1、数据采集间隔时间1 min。分别以0.02 mol.L-1盐酸溶液,pH=4.5磷酸盐缓冲液,pH=6.8磷酸盐缓冲液和水作为溶出介质,浆法,用光程为5 mm的光纤探头监测枸橼酸他莫昔芬片的溶出曲线。并应用相似因子f2法比较溶出曲线的相似性。结果 2个厂家的枸橼酸他莫昔芬片溶出度均符合《中国药典》2010年版规定,但两厂家产品的溶出过程存在差异且同一厂家在不同溶出介质中溶出行为也有很大差异。结论光纤药物溶出实时测定仪能准确连续地反映药物的溶出过程,所得数据完整、真实。     

Dynamics of dissolution and diffusion-controlled drug release systems

Analytical expressions were derived to explain the influence of the dissolution/diffusion number (Di) on the time constant and steady-state flux when dispersed drugs are released from a finite matrix. A key novelty of this work is the introduction of a single time-constant that combined the analysis of both dissolution- and diffusion-based systems. Focus is placed on systems with a constant dissolution rate and diffusion coefficient. Solutions, based on the residue theorem, were in agreement with published results describing the transport of estradiol in a polymeric matrix. The experimental cumulative amount of drug released was 0.1 mg/cm2 in 100 hours compared to 0.084 mg/cm2 predicted by the theoretical model. The process time constant, estimated from the first eigenvalue (t0) and a more accurate statistical approach (t(eff)), showed a consistent decrease with increasing Di values. For a dissolution/diffusion number of 0.21, t0 and t(eff) were estimated at 58.44 and 73.02 hrs, respectively. With the presence of a skin layer, t(eff) increased to 575.7 hrs. These results can be used to assess the relative impact of dissolution and diffusion on the time it takes drugs to attain a therapeutic level in the bloodstream.     

Physical properties and dissolution behaviour of nifedipine/mannitol solid dispersions prepared by hot melt method

Solid dispersions of nifedipine (NIF) with mannitol in preparations containing 10 and 50% (w/w) of drug were manufactured by the hot melt method. Physical properties and the dissolution behaviour of binary systems as physical mixtures and solid dispersions were investigated. In all samples, the crystal structure of NIF was confirmed using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) revealed, there was no interaction between drug and carrier, however, FTIR spectra indicated formation of thermodynamically less stable polymorph of mannitol. The dissolution rate of NIF from solid dispersions was markedly enhanced, the effect being stronger at higher drug loading (50%, w/w, NIF). The dissolution rate enhancement was attributed to improved wetting of NIF crystals due to mannitol particles, attached on the surface, as inspected by means of SEM. Thermal stability of NIF, mannitol and two other potential carbohydrate carriers (lactose and saccharose) during the hot melt procedure was investigated using 1H NMR. NIF was found to be thermically stable under conditions applied. As expected, among carriers only mannitol demonstrated suitable resistance to high temperature used in experiments.