Dissolution Characteristics of Benzoic Acid and Salicylic Acid Mixtures in Reactive Media

The dissolution rates of mixtures of the two acids, benzoic acid and salicylic acid were determined in a phosphate buffered medium. Dissolution properties from compressed discs under sink conditions were essentially linear. Plots of dissolution rate versus compact composition deviated from the two component models for both non-interacting and interacting components. Dissolution rates, particularly for benzoic acid at intermediate weight fractions, were lower than predicted by the theory for two non-interacting components. These lower than expected rates were explained in terms of the physicochemical changes occurring in the microenvironment at the solid liquid interface.     

高效毛细管电泳法测定杀菌防腐剂中的苯甲酸和水杨酸

本文研究了用高效毛细管电泳(HPCE)法测定苯甲酸和水杨酸的最佳分离条件。将该方法用于杀菌防腐剂中的苯甲酸和水杨酸的测定时,具有快速、简单、试剂用量少等特点。     

Batch Variation of Magnesium Stearate and its Effect on the Dissolution Rate of Salicylic Acid from Solid Dosage Forms

The effects of different batches of magnesium stearate on the release of salicylic acid from capsules and from a compacted formulation have been investigated. The results indicate that retardation of salicylic acid release becomes independent of the particle size of magnesium stearate when the blending of the two substances prior to encapsulation or compaction is prolonged for a sufficient time.

Variation in the release rates observed after prolonged blending times have been shown to exhibit a rank order correlation with the different hydrophobicities of the batches of magnesium stearate as indicated by the results of contact angle measurements on drops of dissolution medium on compacts of this lubricant.

Determination of the surface tension of an aqueous extract of each batch of lubricant has indicated that water-soluble, surface-active impurities may be responsible for this apparent variation in the degree of hydrophobicity and hence for the change in the release rate of salicylic acid from solid dosage forms when they are manufactured with different batches of magnesium stearate.     

高效液相法测定酱油中山梨酸、苯甲酸

在酱油样品处理时分别加入亚铁氰化钾和乙酸锌溶液沉淀蛋白质、脂肪并过滤后进行测定。试验结果表明在相应的试验浓度范围内具有良好的线性关素,相关系数大于0.997,回收率在93.2%~105.8%之间,准确度高、重现性好。     

Percutaneous Absorption of Salicylic Acid in Rabbits

The pharmacokinetic parameters defining the percutaneous absorption of salicylic acid in rabbits have been investigated. A one compartment open model with apparent first order absorption was found to describe adequately the blood level data.     

毛细管区带电泳法测定饮料中苯甲酸和山梨酸

应用毛细管区带电泳技术,建立了饮料中苯甲酸、山梨酸测定方法,并通过对电泳缓冲溶液浓度及pH、进样溶液pH等电泳条件的优化,提高了方法的灵敏度。苯甲酸检出限0.4mg/L,山梨酸检出限0.2mg/L,本方法的回收率在96％～102％之间。该方法具有前处理简便、快速、准确等特点,饮料只需用缓冲液稀释即可直接进样,3分钟内出结果,重现性好。     

Dissolution Characteristics of Interactive Powder Mixtures. Part One: Effect of Solubility and Particle Size of Excipients

Abstract

Interactive mixtures of fine cohesive drug powders and coarse free flowing excipients are reported to increase dissolution rates of poorly soluble drugs. However, dissolution rates are known to be affected by the solubility characteristics of the excipients as well as excipients surface characteristics after mixing with lubricant.

In this study the effects of solubility and particle size of excipients on dissolution of micronized griseofulvin from interactive powder mixtures were investigated. Quantitative assessment of dissolution from such mixtures showed that systems containing soluble excipients increased dissolution of the drug more efficiently than mixtures prepared using insoluble excipients. The role of the soluble excipient was more significant after mixing with magnesium stearate. Excipients of smaller particle sizes increased dissolution more efficiently than their large size counterparts. Effects of particle size were particularly significant in case of water insoluble excipients.     

Dissolution Rates of Trimethoprim-Sulphamethoxazole and Trimethoprim Tablets in Aqueous Media

Abstract

Dissolution rates of trimethoprim and sulphamethoxazole from combination tablets showed a rapid release of trimethoprim in acid media from all formulations. Sulphamethoxazole showed a more variable release pattern and faster release in dilute acid medium compared with the less acidic simulated gastric fluid. Tablets containing only trimethoprim showed a release rate into hydrochloric acid media that was dependent upon pH. Approximately twice the amount of trimethoprim was released in twenty minutes at pH 1.32 compared with pH 6.50.     

苯甲酸改性纳米氧化锌的制备及表征

利用苯甲酸对纳米氧化锌进行表面改性,用亲油化度和吸水率表征改性效果,确定其最佳改性工艺为:苯甲酸质量分数为15%,改性温度为100~105℃,改性时间为2 h。通过X射线衍射、红外光谱、透射电镜、沉降实验和接触角测试,对改性前后的样品进行表征。结果表明,苯甲酸对纳米氧化锌的改性属于化学改性,苯甲酸的羧基与纳米氧化锌表面的羟基发生键合反应,从而改变了纳米氧化锌的性能;改性后的纳米氧化锌样品结晶度高,分散性好,疏水性明显提高。     

The Solubility of Salicylic Acid in Supercritical Carbon Dioxide

The possibility of using the method of supercritical fluid extraction for purifying the product of synthesis of salicylic acid is revealed and confirmed experimentally. A continuous-flow experimental setup is used to investigate the solubility of salicylic acid and phenol in supercritical CO₂ and to purify the product of synthesis of salicylic acid at a temperature of 308 K in the pressure range from 7.8 to 12 MPa. The salicylic acid content of the resultant product conforms to the requirements of the State Pharmacopoeia.     

Dissolution Characteristics of Pharmaceutical Equivalents

The in-vitro release of diltiazem from pharmaceutical equivalents of sustained release tablets, commercially available in Italy, was studied.

The in-vitro release profiles were determined by means of different methods and apparatus. Paddle, basket, Poole, Diffutest and Stricker methods were compared.

The absorption rates in artificial gastric and enteric juices by means of lipid barriers were calculated.

Some preparations showed a diffusion mechanism, some a first-order release.

The differences among the dissolution profiles of the formulations were enhanced with the Strieker method.     

Dissolution Characteristics of Pharmaceutical Equivalents

Abstract

The in-vitro release of diltiazem from pharmaceutical equivalents of sustained release tablets, commercially available in Italy, was studied.

The in-vitro release profiles were determined by means of different methods and apparatus. Paddle, basket, Poole, Diffutest and Stricker methods were compared.

The absorption rates in artificial gastric and enteric juices by means of lipid barriers were calculated.

Some preparations showed a diffusion mechanism, some a first-order release.

The differences among the dissolution profiles of the formulations were enhanced with the Strieker method.     

Solid State and Dissolution Rate Characterization of Co-Ground Mixtures of Nifedipine and Hydrophilic Carriers

ABSTRACT

Co-ground powders of the poorly water-soluble drug nifedipine and a hydrophilic carrier, [partially hydrolyzed gelatin (PHG), polyvinylpyrrolidone (PVP), sodium dodecyl sulfate (SDS), hydroxypropyl methylcellulose (HPMC), polyethylene glycol (PEG), urea or Pluronic F108] were prepared in order to improve the dissolution rate of nifedipine. The effects of type of grinding equipment, grinding time, and type of hydrophilic carrier on the crystallinity of nifedipine (x-ray diffraction and differential scanning calorimetry) on the interaction between drug and carriers (differential scanning calorimetry), on the particle size and appearance (scanning electron microscopy), on the wettability (contact angle measurements), and on the drug release were investigated. Grinding nifedipine together with these carriers improved the dissolution rate. PHG-ground mixtures resulted in the fastest dissolution rate followed by PVP, SDS, HPMC, Pluronic, urea, and PEG. This effect was not only due to particle size reduction, which increased in the order PHG < PEG = SDS < Pluronic < drug < urea < HPMC < PVP, but also resulted from the ability of some carriers (PVP and HPMC) to prevent reaggregation of the finely divided drug particles. PVP, HPMC, and PHG formed a powder with amorphous drug. The carriers improved the wettability of the ground products in the order HPMC < drug < urea < PVP < SDS < PHG < PEG < Pluronic. Differential scanning calorimetry (DSC) measurements gave valuable information about the nature of drug crystallinity and the interactions with the carriers within the ground mixtures.     

水杨酸分光光度法测定水溶液中硝酸根浓度的研究

随着工农业生产的迅速发展,工业品以及化肥被大量使用,我国的水环境硝酸盐污染日益严重[1]。当前,我国水环境中硝酸根的标准测定方法主要有酚二磺酸法、离子色谱法、紫外分光光度法等[2]。本研究利用硝酸盐物质在碱性溶液中与水杨酸钠作用,生成黄色的酚硝基衍生物这一特性,利用行分光光度计对溶液中硝酸盐的浓度进行测定。该方法操作简单,成本低,结果令人满意。     

环烷酸中亚磷酸三苯酯对A3钢的缓蚀性能和膜的溶解性能

采用静态挂片和SEM方法,考察了亚磷酸三苯酯在环烷酸腐蚀体系中对A3钢的缓蚀性能.结果表明,亚磷酸三苯酯具有很好的缓蚀性能,它可以在金属表面形成致密的膜,该膜在不添加缓蚀剂的情况下,在环烷酸中可以保持60 h以上的耐腐蚀性能,显示了亚磷酸三苯酯作为缓蚀剂具有很好的后效性.     

水杨酸原位表面改性纳米TiO2的制备及性能研究

通过控制四氯化钛(TiCl4)的水解速度,制备出水杨酸(SA)原位表面修饰的TiO2纳米颗粒(TiO2/SA).通过X射线衍射仪(XRD),高分辨透射电子显微镜(HRTEM),红外光谱仪(FT-IR),热分析(TG-DTA)和X射线光电子能谱(XPS)等实验分析手段对表面改性前后的TiO2纳米颗粒进行了表征,结果表明表面修饰水杨酸的TiO2纳米颗粒在乙醇中有良好的分散性,将TiO2/SA加入到光信息存储薄膜材料(PVA/AM)中,能大大提高材料的衍射效率,降低布拉格偏移.     

Hydrate Related Dissolution Characteristics of Norfloxacin

Abstract

The effect of moisture and temperature on the physical and chemical stability of solid oral dosage forms of Norfloxacin was studied. The physical properties of the dosage form, i. e. breaking strength and disintegration time were not affected adversely. Dissolution characteristics of Norfloxacin tablets were found to be affected by humidity conditions. Tablets with poor dissolution characteristics were improved to satisfactory rates by exposure to 21–25°C/75% relative humidity. Exposure to lower humidities and higher temperatures adversely affected dissolution rates. Once favorable dissolution rates were attained, however, they remained unchanged in spite of dehydration of the tablets.     

Metrological Characteristics of K-1 and K-3 Reference Benzoic Acids

A principle is presented for reproducing the unit of combustion energy, the joule, on the GÉT 16-96 State Primary Standard, which is based on using high-purity benzoic acid grade K-1. Metrological characteristics are given for various types of benzoic acid produced in various countries and used in combustion calorimetry. A comparison is made of the combustion energies for Russian K-3 benzoic acid and American 39i, which have been obtained with a GÉT 16-96.     

Impedance Behavior of Anodic Dissolution of Vanadium in Sulphuric Acid

The anodic dissolution of vanadium in 0.5 H₂SO₄ in the potential range of E_corr to 2000 mV (SCE) Was investigated by DC polarization electrochemical impedance spectroscopy, (EIS). The impredance behaviour can be satisfactory described by a series of corrosion reactions where changes in the surface during the various stages of corrosion are emphasized. Study of the effect of temperature on the vanadium at open circuit potential and the value of activation energy support one-electron transfer step as the rate-determining corrosion process.