Physicochemical characterization and dissolution enhancement of loratadine by solid dispersion technique

The purpose of this investigation was to enhance the dissolution rate of loratadine using polyethylene glycol 6000 (PEG) solid dispersions (SDs). The solubility behavior of loratadine in the presence of polyethylene glycol 4000 and polyethylene glycol 6000 in water showed linear increase with increasing concentrations of PEG, indicating A _L type solubility diagrams. SDs of loratadine with PEG 6000 were prepared at 1: 1, 1: 3, 1: 5, 1: 7 and 1: 9 ratios by the solvent evaporation method. Solid dispersions were characterized for drug content, dissolution behavior and for physicochemical characteristics. The dissolution rate of loratadine was enhanced rapidly with increasing concentrations of PEG 6000 in SDs. Fourier transform infrared (FTIR) studies showed the stability of loratadine and the absence of a well-defined loratadine — PEG 6000 interaction. Differential scanning calorimetry (DSC) and X-ray powder diffractometry (XRD) studies revealed the amorphous state of loratadine in SDs of loratadine with PEG 6000 which was further confirmed from scanning electron microscopy (SEM) studies. The flow properties of the blend, physical characteristics and disintegration time of the tablets formulated indicated that PEG 6000 SD can be used to formulate fast release loratadine tablets.     

水飞蓟素固体分散体的制备及溶解性能研究

筛选出高分子材料制备水飞蓟素固体分散体,提高水飞蓟素的溶解度和溶出速率。分别采用聚乙二醇6000（PEG6000）、聚维酮K30（PVPK30）为载体,制备水飞蓟素固体分散体。采用高效液相法进行含量测定,差示热分析法鉴别药物在载体中的存在状态,并进行溶解度、体外溶出速率实验。结果表明,两种载体的固体分散体均能增加水飞蓟素的溶解度和溶出速率,水飞蓟素在载体中以高度分散状态存在,而非晶型形态存在。以PVPK30为载体明显优于以PEG6000为载体的水飞蓟素固体分散体体外溶解度和溶出速率。     

Fabrication and in vitro characterization of fenofibric acid-loaded hyaluronic acid–polyethylene glycol polymeric composites with enhanced drug solubility and dissolution rate

The target of the present work was to formulate and characterize a fenofibric acid-loaded hyaluronic acid–polyethylene glycol (HA-PEG) polymeric composite to improve solubility and dissolution of the drug in the aqueous media. Several fenofibric acid-loaded HA-PEG polymeric composites were fabricated with varying quantities of HA and PEG 6000 using the solvent-evaporation method. The impact of relative quantities of HA and PEG was examined on solubility and dissolution of the drug. The thermal and structural physiognomies were investigated using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Spectroscopic study was accomplished by Fourier transform infrared spectroscopy (FTIR). Shape and surface features of the solid particles were observed using scanning electron microscopy (SEM). All the formulations demonstrated greater solubility and dissolution than did plain fenofibric acid powder. Both the HA and PEG positively affected solubility and dissolution of the drug in the aqueous media. A fenofibric acid-loaded HA-PEG polymeric composite, consisting of fenofibric acid/HA/PEG at the weight ratio of 0.5/6.0/0.75, respectively, provided the highest solubility (0.45?±?0.05?mg/mL) and dissolution (～90% in 15?min) in this study. Moreover, the loaded drug was in the amorphous state, and had no covalent linkages with polymeric matrices. Thus, this HA-PEG polymeric composite might be a suitable drug delivery system for oral administration of fenofibric acid.     

卡维地洛滴丸的制备工艺与表征

本文开发了一种可提高新剂型的可提高难溶性药物卡维地洛溶出的制备方法并进行表征。采用固体分散技术法制备滴丸，通过响应面试验法，按照归一值法优化指标，优选最佳工艺并验证，考察自制滴丸体外溶出度。采用差示扫描量热法（DSC）、粉末 X射线衍射法和红外吸收光谱法鉴定药物在滴丸中的存在状态。结果表明：最优制备工艺为卡维地洛与基质质量比为1∶7，PEG6000与PEG4000质量比为1∶3，滴速为54min^-1，药液温度为75℃，所建模型显著。滴丸在pH1.2的盐酸溶液中30min内释药最快，达到90%以上，其次为pH4.5、pH6.8、去离子水。所制3批滴丸重现性好，体外溶出相似（f ₂>85），稳定性好。药物在滴丸中主要以无定形状态存在，可提高难溶性药物的溶出，为卡维地洛新的口服速释剂型的开发提供参考。     

Preparation and characterization of genistein containing poly(ethylene glycol) microparticles

The purpose of this study was to prepare, characterize, and evaluate genistein‐containing microparticles with enhanced dissolution profile using poly(ethylene glycol) (PEG) as polymer matrix. Genistein loaded microparticles were prepared by a solvent evaporation process and their surface, thermal, chemical, and dissolution properties were analyzed by microscopy, differential scanning calorimetry, ATR‐FTIR spectroscopy, and USP dissolution apparatus II, respectively. The wettability index was also determined. Genistein exhibited an elongated crystal habit. However, the drug containing PEG microparticles were discrete and quasispherical. The ATR‐FTIR studies performed on the formulation suggested hydrogen bonding between the drug and the polymer matrix. Thermal analysis indicated a conversion of the crystalline form of the drug to an amorphous form. Genistein, exhibiting low solubility and high permeability, is a Class II drug of the Biopharmaceutical Classification Scheme. However, there was a ～9‐fold increase in the rate of dissolution of genistein in the case of all formulations as compared to native genistein. This study showed that genistein could be effectively encapsulated into PEG microparticles using an emulsion‐solvent evaporation technique, therefore avoiding the potential disadvantages of other solid dispersion techniques. This approach provided a significant enhancement in the drug dissolution profile. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2070–2078, 2006     

Micronization of Gefitinib Using Solution‐Enhanced Dispersion by Supercritical CO2

The antineoplastic gefitinib has a low aqueous solubility, leading to poor absorption rates. To overcome this problem, microparticles (MP) were prepared using solution‐enhanced dispersion by supercritical fluids (SEDS) with supercritical CO₂ and the cosolvents dichloromethane and ethanol. The results showed that the use of SEDS resulted in the formation of smaller particles and rendered the usually heterogeneous crystals of the crude drug pure and uniform. Furthermore, the reduction in the MP size increased the dissolution rate of gefitinib, and in vitro cytotoxicity assays indicated that the MP inhibited the proliferation of A549 cells to a larger extent than did the crude drug. Given the beneficial properties of the MP, SEDS could potentially be used to micronize drugs for therapeutic applications.     

Dissolution enhancement of flavonoids by solid dispersion in PVP and PEG matrixes: A comparative study

Polyvinylpyrrolidone (PVP) and poly(ethylene glycol) (PEG) solid dispersion systems with flavanone glycosides, naringin and hesperidin, and their aglycones, naringenin and hesperetin, were prepared, using solvent evaporation method, to enhance their dissolution rates that may affect their bioavailability. Drug release of both flavanone glycosides and their aglycones was directly affected by the physical state of solid dispersions. Powder‐XRD technique in combination with scanning and transmission electron microscopy revealed that PVP polymer formed amorphous nanodispersion systems with flavanone aglycones, while such systems could not be formed with their glycosides, which are bulkier molecules. Fourier transform infrared spectra suggest the presence of hydrogen bonds between PVP carbonyl groups and hydroxyl groups of both flavanone aglycones. These interactions prevent the crystallization of naringenin and hesperetin aglycones in PVP matrix. On the other hand, the ability of PEG carrier to form hydrogen bonds with flavanone glycosides or aglycones was limited, and as a result both flavanone glycosides and their aglycones remain in the crystalline form. For this reason, the solubility enhancement of PEG solid dispersions was lower than when PVP was used as drug carrier. At pH 6.8, the % release of naringenin and hesperetin from PVP/naringenin–hesperetin (80/20 w/w) solid dispersion was 100% while in PEG solid dispersions, it was not higher than 60–70%. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 460–471, 2006     

Impregnation of PVP microparticles with ketoprofen in the presence of supercritical CO2

The aim of the work is to enhance the oral bioavailability of ketoprofen by inserting it into a water-soluble polymer, poly(vinylpyrrolidone) (PVP) K30, using supercritical carbon dioxide as the impregnating solvent. Ketoprofen is a non-steroidal anti-inflammatory drug (NSAID) characterized by low solubility and a low dissolution rate in the gastrointestinal tract, PVP is a biocompatible water-soluble polymer with a fast dissolution rate and supercritical CO₂ is a clean non-toxic solvent that is able to plasticize amorphous polymers.The physical state of the drug in the polymer has been investigated through Fourier Transform Infrared (FTIR) spectroscopy and powder X-ray diffraction (PXRD) and it has been compared with that of the PVP-ketoprofen physical mixtures. The results of the analyses show that an amorphous solid dispersion of the drug in the polymer can be obtained even at high concentrations.Impregnated polymer powders were compressed into tablets and the release kinetics was evaluated to study the drug dissolution rate. The release curves of the physical mixtures, with the same drug content, were also measured and compared with those of the impregnated polymer tablets. The results show that the release mechanism depends on the tablet composition and that it is necessary to work with not too high a drug content to obtain a large enhancement of the dissolution kinetics.     

308.2 K三元体系KCl+PEG10000/20000+H2O相平衡及热力学计算

采用等温溶解平衡法和浊点法分别测定了308.2 K时三元体系KCl+PEG10000/20000+H₂O的固液平衡组成和液液平衡组成,同时测定了固液平衡时体系的密度和折射率。根据实验数据,绘制了两个三元体系308.2 K时的完整相图、双液线对比图和结线-组成图。研究发现：三元体系KCl+PEG10000/20000+H₂O 308.2 K时的完整相图均包含6个区域：不饱和液相区（L）,2个一固一液区（L+S）,双液相区（2L）,两液一固区（2L+S）,两固一液区（L+2S）;其中,一液两固区（L+2S）中的两种固相分别为KCl和PEG10000/20000。在完整相图中,一固一液区面积最大,双液相区面积最小。对比308.2 K时聚乙二醇分子量为1000、4000、6000、10000和20000的KCl+PEG+H₂O体系可知：分子量为1000、4000和6000时,体系中仅存在固液相平衡关系;分子量为10000和20000时,体系中同时存在固液和液液相平衡关系,且随着聚乙二醇分子量的增加,双液线向原点移动,双液相区（2L）和两液一固区（2L+S）增大,不饱和液相区（L）和一固一液区（L+S）均减小。采用Chen-NRTL-PDH热力学模型进行了液液相平衡计算,计算结果与实验数据吻合较好。     

Cogrinding as an approach to enhance dissolution rate of a poorly water-soluble drug (gliclazide)

Gliclazide is practically insoluble in water. In order to improve the drug dissolution rate, cogrinding method was used as an approach to prepare gliclazide coground/solid dispersions (SDs) in the carriers such as povidone (PVP-K30), crospovidone and microcrystalline cellulose (Avicel PH 101) with different drug to carrier ratios. The dissolution rate of gliclazide from the SDs was measured at two physiological pH values of 1.2 and 7.2 simulating gastric and intestinal fluids using USP dissolution apparatus II. The concentration of the dissolved drug in the medium was determined by direct or first-derivative UV spectroscopy. The dissolution rates of the formulations were dependent on the nature and ratio of drug to carriers in SDs and the corresponding physical mixtures as well as the pH of the medium. At a higher pH the drug has a faster dissolution than at a lower pH. The fastest dissolution rates were observed from coground formulations with the drug to carrier ratio of 1:5. The amount of drug dissolved in 15 min from these SDs was varied from 96% in the case of Avicel SD to 100% for SD of PVP. Whereas the amount of drug released in the same time from unground drug powder (UD), ground drug powder (GD) and all physical mixtures was between 60 and 80%. These results indicate that the dissolution rate is highly enhanced from the SDs. DSC as well as X-ray diffraction showed reduced drug crystallinity in SDs. Scanning electron microscopy and particle size analysis revealed significant decreased particle size of the drug in SDs. FT-IR spectroscopy demonstrated no detectable interactions between the drug and carriers. In addition to latter evidence, increased wettability and hydrophilicity of drug particles and deaggregation brought about by the carriers are the reasons for enhanced drug dissolution from the SDs. One of the possible advantages of formulating an insoluble drug such as gliclazide is that if it is used in preparation of capsules or tablets of the drug, its dose might be reduced which is economically beneficial.     

超临界流体沉积技术制备负载型金属催化剂的研究进展

综述了近年来超临界流体沉积技术在制备负载型金属纳米催化剂方面的应用及研究进展,介绍了近年来学者们利用超临界流体特殊的溶剂化特征、近乎于零的表面张力、高扩散系数、低黏度、易调变等优势,制备负载型金属纳米催化剂的研究成果。主要从超临界流体沉积过程中金属前驱盐的溶解、吸附、还原3个方面分别进行了阐述。集中讨论了对沉积效果影响显著的溶解度、吸附热力学、扩散动力学以及还原方法等问题。此外,还针对目前超临界流体沉积技术在制备金属纳米复合材料中所遇到的提高金属利用率、颗粒尺寸控制、分散性等焦点问题进行了讨论。     

A new model for predicting solute solubility in supercritical fluids based on the Wilson equation

In this work, a new model based on the Wilson solution theory was proposed for predicting the solubility of solids in supercritical fluid (SCF) with and without cosolvent(s) of binary and ternary systems via computation of activity coefficients. For binary systems the model contains two adjustable parameters, while for ternary systems there are four adjustable parameters. The calculated results of the proposed model were compared with that of the literature models, and it is shown that the proposed model is a more accurate one.     

Hyperbranched poly(glycerol esteramide): A biocompatible drug carrier from glycerol feedstock and dicarboxylic acid

Polymer carrier with biodegradable, biocompatible as well as solubility enhancing properties are highly looked upon in the pharmaceutical industry to improve the drug delivery systems. A series of hyperbranched poly(glycerol esteramide) (HPGEA) with M_w of 5000–12,000 Da, degree of branching of 57%–62%, and hydroxyl values of 200–280 mg KOH/g sample were synthesized through polycondensation of N,N-bis(2-hydroxyethyl)stearamide (diethanolamide) and poly(glycerol ester) (PGE). The HPGEAs were characterized by ATR-FTIR, GPC, ¹H and ¹³C-NMR, and DSC. The enthalpy of fusion of HPGEAs (43–84 J g⁻¹) were lower than the commercial polymers (193–391 J g⁻¹), indicating its potential as drug carrier for solid dispersion (SD). HPGEA-based SDs showed substantial enhancement in solubility and release rate than pure drug, commercial polymer-based SDs, as well as commercial formulation. The safety of HPGEAs and HPGEA-based SDs were proven through MTT assay with IC₅₀ of 2400–9800 and 1200–3500 μg ml⁻¹, respectively.     

CsCl-PEG8000-H2O三元体系288.2、298.2、308.2K相平衡测定

采用等温溶解法和浊点法研究了288.2、298.2、308.2 K下三元体系CsCl-PEG8000-H₂O的相平衡关系,采用经验方程分别对双液线和结线数据进行了拟合,绘制了完整相图。研究发现CsCl-PEG8000-H₂O体系在288.2、298.2、308.2 K下同时存在固液平衡与液液平衡关系,其完整相图均由不饱和液相区（L）、两个一液一固区（L+S）、双液相区（2L）、两液一固区（2L+S）和两固一液区（2S+L）构成;随着温度升高,不饱和液相区（L）、双液相区（2L）、一液一固区（L+S）、两液一固区（2L+S）均增大,两固一液区（2S+L）减小。对比288.2、298.2、308.2 K下三元体系CsCl-PEG1000/4000/6000/8000-H₂O完整相图,结果表明：288.2、298.2 K时,仅CsCl-PEG1000-H₂O体系存在固液平衡关系,CsCl-PEG4000/6000/8000-H₂O体系同时存在固液和液液平衡关系;308.2 K时,CsCl-PEG1000/4000/6000/8000-H₂O体系同时存在固液和液液平衡关系;双液相区（2L）随聚乙二醇分子量增大而增大。     

Influence of the microwave technology on the physical-chemical properties of solid dispersion with Nimesulide

This work describes a new approach to prepare solvent-free solid dispersions (SDs) for Nimesulide (NMS), involving the use of microwaves irradiation (MW). In particular, the microwave technology has been considered in order to prepare an enhanced release dosage form for the poorly soluble drug Nimesulide (NMS), employing Gelucire^® 50/13 and Poloxamer 188 (Lutrol^® F 68) as surfactant carriers. Their physico-chemical characteristics and dissolution properties were compared to the corresponding physical mixtures and the drug alone. The results attested a correspondence of the solid state of the drug before and after the irradiation treatment and that an amorphisation form of the drug in SD systems was obtained. After six months this data was confirmed. These results, together with the presence of the selected carriers, determined a remarkable enhancement of solubility and an in vitro dissolution rate of the drug suggesting that the microwave technique could be considered as a new and interesting method to prepare drug-polymer systems.     

Prediction of Solubility of Cholesterol in Supercritical Solvents

In this study the solubility of cholesterol was calculated in two supercritical pure solvents (carbon dioxide and ethane) as binary systems, and four supercritical solvent/co-solvent systems as ternary systems (cholesterol/carbon dioxide/methanol, cholesterol/ethane/acetone, cholesterol/ethane/hexane, cholesterol/ethane/propane) in various temperatures by SRK, PR, and SAFT equations of state. Pure molecular parameters of SAFT equation of state were obtained by fitting vapor pressure and liquid density data. Also the molecular parameters of cholesterol were obtained by fitting the solubility data of binary systems in one temperature, then they were used for the same system in other temperatures and for ternary systems with the same solvent. Results show that the SAFT equation of state can predict the trend and amount solubility of cholesterol in supercritical solvents much better than the other equations of state.     

超临界流体改质煤焦油研究进展

中国是一个多煤少油的国家，煤制油技术在我国有着广泛的应用前景。由于超临界流体对有机物有较好的溶解性，因此越来越多地应用到煤焦油深加工过程中。本文总结了超临界流体改质煤焦油过程中，操作参数对煤焦油轻质化的影响和强化改质方法，重点分析了超临界水和超临界甲醇，超临界水改质煤焦油主要体现在物理上的溶解和分散作用，而超临界甲醇除此之外，有一定的供氢能力，可以为反应提供氢，但是供氢能力有限。因此，本文又讨论了添加催化剂、自由基引发剂、加氢等手段强化超临界流体改质煤焦油。在此基础上对超临界流体改质煤焦油进行了展望，将超临界流体的萃取和超临界改质耦合在一起，充分发挥超临界流体优越性；选择新的超临界流体、催化剂等促进煤焦油轻质化。     

超临界CO2流体中染料溶解度研究进展

综述了超临界CO2流体中染料溶解度的测试装置与方法。分析了超临界CO2流体工艺参数与染料化学结构对分散染料溶解度的影响规律；总结了国内外近二十年的分散染料在超临界CO2流体中溶解度数据，并介绍了分散染料在超临界CO2中的溶解度增溶技术。指出加强染料结构对其溶解性能作用原理及影响规律剖析，超临界CO2中染料溶解行为数据库构建，染料拼色与配色研究三方面为未来的研究重点。     

喜树碱-七元瓜环包合物的制备及溶解性的考察

采用共蒸发法制备了喜树碱一七元瓜环固体包合物,x-射线粉末衍射及红外光谱证实喜树碱与七元瓜环形成了固体包合物。通过紫外分光光度法考察了包合物的包合率、溶解度和溶出速度。包合物的产率和包合率都达到了80％以上,包合物能使药物的溶解度提高了近70倍,在pH=1．00介质中10min内药物即可达到100％的溶出。     

Development of artificial neural network models for supercritical fluid solvency in presence of co-solvents

This paper presents the application of artificial neural networks (ANN) to develop new models of liquid solvent dissolution of supercritical fluids with solutes in the presence of cosolvents. The neural network model of the liquid solvent dissolution of CO₂ was built as a function of pressure, temperature, and concentrations of the solutes and cosolvents. Different experimental measurements of liquid solvent dissolution of supercritical fluids (CO₂) with solutes in the presence of cosolvents were collected. The collected data are divided into two parts. The first part was used in building the models, and the second part was used to test and validate the developed models against the Peng-Robinson equation of state. The developed ANN models showed high accuracy, within the studied variables range, in predicting the solubility of the 2-naphthol, anthracene, and aspirin in the supercritical fluid in the presence and absence of co-solvents compared to (EoS). Therefore, the developed ANN models could be considered as a good tool in predicting the solubility of tested solutes in supercritical fluid.