Evaluation and comparison of five matrix excipients for the controlled release of acrivastine and pseudoephedrine

For treatment of allergic rhinitis, acrivastine with pseudoephedrine in Semprex®-D conventional capsules requires dosing every 6-8 hours. This study was designed to develop a controlled release matrix tablet of acrivastine and pseudoephedrine and evaluate 5 different matrix excipients for their in vitro controlled-release profiles. Compritol® 888ATO, Eudragit® RS, Methocel® K100M, Polyox® WSR301 and Precirol® ATO5 were used alone or in varying combinations for the formulation of controlled release matrix tablets. In vitro drug dissolution and mathematical modeling were used to characterize drug release rate and extent. All tablet formulations yielded quality matrix preparations with satisfactory tableting properties. Due to the aqueous solubility of pseudoephedrine and the size of the dose, none of the matrix excipients used alone prolonged drug release significantly to meet the desired twice-daily administration frequency. The use of two excipients in combination, however, significantly decreased the dissolution rate of both active ingredients. A combined lipid-based Compritol® and hydrophilic Methocel® produced optimal controlled drug release for longer than 8 hours for both acrivastine and pseudoephedrine.     

Nanoparticle engineering processes for enhancing the dissolution rates of poorly water soluble drugs

Poor water solubility is an industry wide issue, especially for pharmaceutical scientists in drug discovery and drug development. In recent years, nanoparticle engineering processes have become promising approaches for the enhancement of dissolution rates of poorly water soluble drugs. Nanoparticle engineering enables manufacturing of poorly water soluble drugs into nanoparticles alone, or incorporation with a combination of pharmaceutical excipients. The use of these processes has dramatically improved in vitro dissolution rates and in vivo bioavailabilities of many poorly water soluble drugs. This review highlights several commercially or potentially commercially available nanoparticle engineering processes recently reported in the literature for increasing the dissolution properties of poorly water soluble drugs.     

动力堆燃耗测定的样品溶解

文章介绍动力堆燃料燃耗测定中样品的溶解方法,试验不同浓度ＨＮＯ３－ＨＣｌ混合液在沸腾温度下溶解ＵＯ２冷样品的效果,以萤光光度计测定溶解液的透明度予以判别。用７．５ｍｏｌ．ｌ＾－１ＨＮＯＥ－ＨＣｌ混合液（ｃ（ＨＮＯ３）：ｃ（ＨＣｌ）＝４：１）,溶解热样品,溶解液涂片在超显微镜下检查未见不溶颗粒存在。     

Dissolution of magnetite coupled galvanically with iron in environmentally friendly chelant solutions

The galvanic coupling between magnetite and iron in ethylenediaminedisuccinic acid (EDDS) solutions both with and without added iron(II) ions has been studied using electrochemical methods. The galvanic coupling accelerates the corrosion of iron due to the small shift in its potential in the anodic direction. At the same time, the potential of magnetite is cathodically polarized away from the potential range where the only faradaic process—the reductive dissolution of magnetite—takes place and results in a considerable decrease in its dissolution. Magnetite dissolves faster at the galvanic potential when [EDDS] ? [Fe²⁺] whereas iron is affected to a much lesser extent. The ratio between the rates of dissolution of magnetite at the galvanic potential to that at its steady state potential tends to decrease at higher temperatures and at higher EDDS and Fe²⁺ concentrations. This study shows that temperature plays a decisive role in the dissolution of magnetite coupled to iron. To completely remove it from the iron surface, high temperatures should be used. Corrosion inhibitors have to be considered when high losses of the base metal cannot be tolerated.     

Dissolution behavior of spent MgO–C refractory in the CaO–SiO2–FeO slag system as a steelmaking flux

A large amount of spent MgO–C refractory is generated in steel plant every year. Because of the similarities in chemical and mineralogical composition of slag formers and MgO–C refractory, it is possible to reuse the spent MgO–C refractory as a steelmaking flux. To achieve this goal, it should promote the dissolution of MgO–C refractory during slag forming. In this study, the effect of slag composition on the dissolution behavior of spent MgO–C refractory in the CaO–SiO₂–FeO slag system and the dissolution kinetics were investigated. It showed that the dissolution rate of MgO–C refractory was controlled by surface chemical reaction. The dissolution of MgO–C refractory led to an increase in the MgO content in slag while the FeO content decreased because the graphite in refractory was oxidized by FeO. Increasing temperature significantly promoted the dissolution of MgO–C refractory. The MgO–C refractory was readily dissolved in the low-basicity slag. A higher FeO content in slag was beneficial for the oxidation of graphite in refractory, resulting in better dissolution. The dissolution thickness of MgO–C refractory could exceed 4.0 mm under these conditions and its dissolution supplied some MgO to slag.