Effect of Tocopheryl Polyethylene Glycol Succinate on the Percutaneous Penetration of Minoxidil from Water/Ethanol/Polyethylene Glycol 400 Solutions

ABSTRACT

We described to achieve the local retention of minoxidil which has penetrated the skin with minimization of its absorption into the general circulation and elimination of local irritation induced by propylene glycol. The effect of tocopheryl polyethylene glycol succinate (TPGS) on the penetration flux of minoxidil and its retention in the skin from topical minoxidil formulations consisting of water, alcohol, and polyethylene glycol 400 was characterized by an experimental design of ten solvent formulations in this study. Results show that the addition of TPGS was only able to improve the solubility of minoxidil in those solvent systems containing higher proportions of water and PEG 400, and the extent of improvement was also more profound with the addition of TPGS at concentrations higher than 5%. For those solvent systems containing a higher fraction of alcohol, an insignificant change in minoxidil solubility with increasing added amounts of TPGS was noted even with the tendency to decrease the solubility of minoxidil with higher amounts of TPGS. Increasing the amount of TPGS added gradually increased the flux and the corrected flux from solvent formulations with a lower solubility parameter, but decreased those from solvent systems with a higher solubility parameter. With the addition of TPGS, solvent formulation F6 (alcohol:PEG 400 of 50:50) was demonstrated to be the optimal choice by having an improved local effect and a reduced systemic effect compared to the reference of 2% Regaine®. Tocopheryl polyethylene glycol succinate (TPGS) was mainly retained locally in the stratum corneum, and the amount was proportional to the increase in the amount of TPGS added to these ten solvent formulations.     

Phase Formation in Extraction of Metals from Aqueous Salt Solutions with Polyethylene Glycol: 2. Polyethylene Glycol-Water Binary System

The experimental data on water activity in PEG solutions as influenced by the PEG concentration and its molecular weight were analyzed in terms of the polymer solution theory. This analysis shows that nonideality of PEG-water solutions is mainly caused by the athermal effect, namely, by a large difference in the size of water and PEG molecules which, according to Flory theory, causes the increase in the entropy of mixing. The influence of van der Waals interactions and hydration on the solution nonideality was also considered. The PEG hydration number is 2 at the critical temperature of formation of the two-phase system and increases to 4 at lower temperatures. Adequate simulation of the nonideality of the systems concerned is reached with the finite value of the coordination number. In spite of weakness of the van der Waals interactions in the PEG-water systems, their contribution to the nonideality is sufficient to provide a two-phase system. The phase diagrams of the PEG-water system at elevated temperatures are discussed.     

聚乙二醇的等温结晶动力学

用差示扫描量热仪(DSC)研究了聚乙二醇(PEG)的等温结晶动力学。结果表明,在较高温度下处理PEG后,等温结晶过程中,Avrami指数n≈4,表明PEG以均相成核的三维球晶方式生长,同时计算得到结晶活化能为72.013 kJ/mol;而在较低温度处理PEG后,等温结晶过程中,Avrami指数n≈3,表明PEG以异相成核的三维球晶方式生长,结晶活化能为234.791 kJ/mol,比较高温处理后的结晶活化能高,说明PEG的结晶能力随热处理温度的降低而降低。     

4,4'-偶氮二(4-氰基戊酸)聚乙二醇酯大分子自由基引发剂的合成及表征

采用4,4′-偶氮二(4-氰基戊酸)与五氯化磷反应制备了4,4′-偶氮二(4-氰基戊酰氯)。通过聚乙二醇(PEG-1000)和4,4′-偶氮二(4-氰基戊酰氯)进行缩合反应得到了水溶性的4,4′-偶氮二(4-氰基戊酸)聚乙二醇酯大分子自由基引发剂。利用红外光谱(FT-IR)、紫外光谱(UV)、核磁共振(1H-NMR)、凝胶渗透色谱(GPC)对其结构进行了确认和表征。利用差示扫描量热法(DSC)研究了其热分解性能。结果表明,该引发剂的热分解活化能Ea为120.2 kJ/mol,频率因子Ad为1.165×1014s-1。     

不同相对分子质量聚乙二醇的热氧降解行为

3种不同相对分子质量的聚乙二醇(PEG)在80℃经过不同的老化时间,均发生了不同程度的热氧降解。采用红外光谱法、凝胶渗透色谱法和核磁共振波谱法研究了不同相对分子质量聚乙二醇热氧降解的行为及降解产物结构,定量表征了不同相对分子质量聚乙二醇的降解程度。结果表明,老化时间越长,3种PEG降解生成的小分子酯类化合物越多。其中PEG10000最稳定,不易发生热氧降解,PEG800降解程度最大。     

不同含量聚乙二醇对碳化硅喷雾造粒的影响

通过研究碳化硅及其烧结助剂碳化硼、纳米碳黑在水溶液中的共分散性.制得了分散性良好的混合浆料·研究结果发现碳化硅及其烧结助剂碳化硼、纳米碳黑在碱性条件下可以实现共分散.同时聚乙二醇(PEG)作为浆料的分散剂和粉体的粘结剂,PEG含量对碳化硅喷雾造粒有重要的影响,结果显示随着PEG含量的增加,喷雾造粒的球状颗粒形貌趋于规整,粉体的流动性增加.     

Anomalous Behavior of Low Temperature Specific Heat in HgCr2Se4

Low temperature specific heat (C _p ) characterization on high-quality HgCr₂Se₄ single crystal was performed between 0.5 K and 10 K. The result provides conceivable evidence for the existence of competing ferromagnetic (FM) and antiferromagnetic (AFM) interactions in narrow temperature and temperature windows. The result suggests that magnetic interactions competition, as well as the Schottky anomaly, neglected previously in HgCr₂Se₄ due to the fragile AFM interaction and spin-lattice coupling, also play key roles in giving rise to the exotic magnetic behaviors.     

Dissolution Behavior of Griseofulvin Solid Dispersions Using Polyethylene Glycol, Talc, and Their Combination as Dispersion Carriers

Griseofulvin solid dispersions were prepared using polyethylene glycol 6000 (PEG), talc, and their combination as carriers by the solvent method. The dissolution of griseofulvin from these dispersions was studied. It was found that in these carriers the drug dissolution rate was a function of drug loading. The dissolution rate from dispersions prepared using PEG was similar to that from PEG/talc dispersions, especially at a low percentage of drug loading. Dispersions of PEG and PEG/talc provided dissolution rates faster than those from dispersions of talc. The incorporation of talc in PEG yielded dispersions with properties of less tackiness and ease for handling. Dissolution kinetics, based on the Hixson-Crowell equation, was used to determine the characteristics of griseofulvin particles in dispersions. Linear relationships were obtained for PEG and PEG/talc dispersions that indicated the presence of a uniformly sized monoparticulate system, whereas deviation from linearity was observed for talc dispersions. This appeared to be a multiparticulate system in which particles were present as free form and adsorbed form on the surface of talc.     

聚乙二醇模板剂制备介孔材料的研究进展

聚乙二醇作为模板剂被广泛用于介孔材料的制备。介绍了使用单一聚乙二醇模板剂合成硅基、非硅基、复合类介孔材料的研究工作,探讨了聚乙二醇与表面活性剂、非表面活性剂类物质作复合模板剂制备介孔材料的方法。综述了聚乙二醇单一模板剂及复合模板剂制备介孔材料的机理。     

Tensile and Fatigue Analysis of 3D-Printed Polyethylene Terephthalate Glycol

Journal of Failure Analysis and Prevention - This paper investigates the tensile and fatigue behavior of polyethylene terephthalate glycol (PETG) parts manufactured by fused filament fabrication...     

Modeling Viscosity of Multicomponent Electrolyte Solutions

A comprehensive model for calculating the viscosity of aqueous electrolyte solutions has been developed. The model includes a long-range electrostatic interaction term, contributions of individual ions, and a contribution of specific interactions between ions or neutral species. The long-range electrostatic term is obtained from the Onsager–Fuoss theory, whereas the individual ionic contributions are calculated using the Jones–Dole B coefficients. A technique for predicting the temperature dependence of the B coefficients has been developed on the basis of the concept of structure-breaking and structure-making ions. The contribution of specific interactions between species, which is dominant for concentrated solutions, has been found to be a function of the ionic strength. The model reproduces the viscosity of aqueous systems ranging from dilute to concentrated solutions (up to ca. 30m) at temperatures up to 573 K with an accuracy that is appropriate for modeling industrially important systems. In particular, the viscosity of multicomponent systems can be accurately predicted using parameters obtained from single-solute systems.     

自由基聚合法制备聚乙二醇双丙烯酸酯水凝胶

以过二硫酸胺(APS)/四甲基乙二胺(TMEDA)氧化-还原体系为引发体系,通过活性自由基溶液聚合法制备了交联网状聚乙二醇双丙烯酸酯(PEGDA)共聚物水凝胶支架,探讨了APS/TMEDA的引发聚合机理。研究结果表明,单体分子量越大,凝胶化时间越短,凝胶化时间随着PEGDA单体浓度的增大、温度的升高和加速剂用量的增大而减小。研究了不同单体浓度对水凝胶溶胀度及力学性能的影响,结果表明,单体溶液浓度越大,水凝胶的平衡溶胀率越小、压缩模量越强。     

Rectal Absorption of Phenytoin in Rabbits from Polyethylene Glycol Suppositories

Abstract

Various suppositories containing phenytoin and phenytoin sodium were formulated with different polyethylene glycol combinations. The three formulae that had the best in vitro release rate were administered to rabbits. Phenytoin was well absorbed from the suppositories, and the results show that rectal administration of phenytoin can be an alternative to oral administration.     

In vivo Retention Time Evaluation of Polyethylene Glycol Suppository Bases

Ninety six (96) healthy male volunteers between the ages of 21 and 35 received two experimental polyethylene glycol suppository bases and one commercially available base. A comparison of the two experimental bases with the commercially available base indicates that the base containing polyethylene glycol 1000-4000 (65:35) is superior and that the base containing polyethylene glycol 1540-6000 (30:70) is probably comparable to the commercial product. It is concluded that these polyethylene glycols can be used as suppository bases without undue reaction.     

A Note on the Solubility of Progesterone in Aqueous Polyethylene Glycol 400

Abstract

The solubility curve of progesterone in aqueous polyethylene glycol (PEG) 400 at ambient room temperature (～25°C) is bimodal, a break occurring at approximately 60% w/w PEG.

It is speculated that the presence of unbound water in the PEG 400/water system depresses the solubility of progesterone in PEG 400 disproportionately.     

表面修饰聚乙二醇粒子的非等温结晶过程

采用乙基纤维素对聚乙二醇（PEG）粒子进行表面修饰,通过对修饰后PEG粒子和未修饰PEG粒子进行差示扫描量热（DSC）测试,研究PEG材料尺寸对非等温结晶过程的影响.结果发现：表面修饰PEG粒子在球晶生长碰到皮材时结晶结束,而未修饰PEG粒子在球晶生长一段时间后相互碰撞挤压直到填满所有空隙后结晶才结束;表面修饰后结晶半时间和结晶最快时间变短;表面修饰PEG粒子和未修饰PEG粒子在尺寸小于400μm时,表面修饰PEG粒子的结晶峰峰位向高温移动.     

Stability and Dissolution Rates of Corticosteroids in Polyethylene Glycol Solid Dispersions

A study has been made to examine the stability and dissolution rates of prednisolone, prednisone and hydrocortisone formulated as solid dispersions in polyethylene glycols. Of the five PEG samples used, three enhanced the chemical instability of the steroids; the effect being dependent on the PEG sample and storage conditions of the solid dispersions. Dissolution rates of the steroids were relatively fast from the solid dispersions and showed no significant changes upon storage. Using two methods of analysis (direct UV spectrophotometry and the USP blue tetrazolium method), it is concluded that the chemical instability of the steroids in some PEG samples was due to alterations in the dihydroxy acetone side chain. One of the decomposition products found appeared to be an acidic compound resulting from oxidation of the C₁₇ side chain. The oxidation is presumably accelerated by a peroxide impurity in PEG samples.     

Enhanced Dissolution of Ibuprofen Using Solid Dispersion with Polyethylene Glycol 20000

To improve its dissolution, ibuprofen solid dispersions (SDs) were prepared in a relatively easy and simple manner, characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), and evaluated for solubility and in vitro drug release. Loss of individual surface properties during melting and re-solidification as revealed by SEM micrographs indicated the formation of effective SDs. Absence or shifting toward the lower melting temperature of the drug peak in SDs in DSC study indicated the possibilities of drug–polymer interactions. FTIR spectra showed the presence of drug crystalline in SDs. The effect of improved dissolution on the oral absorption of ibuprofen in rats was also studied. Quicker release of ibuprofen from SDs in rat intestine resulted in a significant increase in AUC and C_max, and a significant decrease in T_max over pure ibuprofen. Preliminary results from this study suggested that the preparation of fast dissolving ibuprofen SDs by low-temperature melting method using polyethylene glycol 20000 as a meltable hydrophilic polymer carrier could be a promising approach to improve solubility, dissolution, and absorption rate of ibuprofen.     

双峰分布聚乙烯的动态流变行为

以六种不同分子量分布特征的聚乙烯为研究对象,通过动态流变、高压毛细管流变以及凝胶渗透色谱(GFC)等分析测试手段,对这六种聚乙烯的结构和性能进行对比分析.高压毛细管的结果表明,A样品表现出更好加工稳定性和更宽的加工速率窗口,结合该样品的分子量及分子量分布特别是动态流变行为,笔者认为,样品中高低分子量部分的微相分布状态对...