Effect of Particle Size on the Dissolution Characteristics of Chlorthalidone

Abstract

The particle size reduction of chlorthalidone by fluid energy milling, Alpine milling and Fitzpatrick milling were evaluated. The desired particle size was achieved by both the fluid energy milling and Alpine milling processes. Alpine mil1ing, however, is a more complex process and is susceptible to product decomposition, whereas fluid energy milling is a simple and efficient process without any risk of product decomposition. The desired particle size cannot be achieved by Fitzmilling because of the low probability of impaction force on particles. The dissolution rate of the chlorthalidone from chlorthalidone/propranolol hydrochloride tablets (25/80 mg) prepared with fluid energy milled chlorthalidone was significantly better than the tablets prepared with Fitzpatrick - milled chlorthalidone. The minimum effective specific surface area of chlorthalidone needed for maximum dissolution in water was found to be around 3.5 m²/g.     

Nitrofurantoin: Particle Size and Dissolution

Tablets manufactured from micronized anhydrous nitrofurantoin exhibited unsatisfactory dissolution properties, whereas excellent results were obtained with unmilled drug material having fine particle size.     

Autohated Deterhination of Dissolution Rate: Effect of Particle Size Distribution

The effect of particle size distribution on the dissolution of salicylic acid in an automated dissolution apparatus has been studied. Tablets were prepared by individually weighing 200 mg of the drug particles having a narrow size distribution, compressing the tablets using a hydraulic press and employing identical compression force for the same time period for each tablet. The results showed that the range values obtained were not significantly different from those obtained when the particle size was not controlled. However, the range values obtained from the dissolution of drug particles recovered from the tablet formulation were found to be similar to the range values obtained from the dissolution of the tablet formulation, indicating that compression during tabletting was responsible for observed differences.     

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.     

Effect of Particle Size on the Dissolution Rate of Monophenylbutazone Solid Dispersion in Presence of Certain Additives

Abstract

Monophenylbutazone is a very sparingly soluble drug. The effect of particle size on the dissolution characteristics of monophenylbutazone in a dissolution medium of 0.1 N hydrochloric acid and 0.1 N hydrochloric acid to which was added 0.005% Tween 80, was carried out. The enhancement of the dissolution rate of the medicament was attained by formulating the drug in both solid dispersion and physical mixture using urea and polyethylene glycol 4000 as carriers. A comparative dissolution behaviour of the medicament in different solid dispersion and physical mixture ratios were investigated at particle, size of < 63 μ. Drug-urea solid dispersion of a ratio 5:95% produced the highest dissolution rate.     

Effect of Stearic Acid Particle Size on Surface Characteristics of Film-Coated Tablets

Raw material specifications are vital for many excipients used in the manufacture of tablets. Stearic acid powder is widely used in the pharmaceutical industry as a tablet lubricant. This study shows that the variation in particle size of stearic acid not only affects die wall lubrication properties (ejection force) but also affects surface characteristics of film-coated tablets. A coarser grade of stearic acid can dislodge from tablet surfaces during the film-coating process leaving pit marks, whereas a finer grade of stearic acid (less than 100 mesh) results in film-coated tablets having very smooth surfaces. The mechanism of pitting on the tablet surface is described. A specification for stearic acid particle size to overcome this problem is suggested.     

Effect of Particle Size and Excipients on the Dissolution Rate of Metronidazole from Solid Dosage Forms: I

The use of metronidazole in the treatment of Trichomoniasis, Giardiasis, Amoebiasis and infections caused by anaerobic microbes has been well established. This communication outlines efforts made to design a metronidazole formulation with better absorption properties than the “KLION-Tablet”, currently manufactured by the Chemical Works of Gedeon Richter Ltd., Budapest, A relatively low solubility of the drug in water, and improper selection of vehicles contribute to low dissolution rate, hence limiting the absorption. Particle size reduction and the incorporation of lactose in the finer aggregating powder, showed increased dissolution rate.     

Effect of Particle Size and Excipients on the Dissolution Rate of Metronidazole from Solid Dosage Forms: II

In-vitro dissolution tests were carried out with tablets prepared from different particle size ranges of metronidazole. Influence of tablet binding agents (Methylcellulose, polyvinyl pyrrolidone - (PVP), potato starch and gelatin) on the drug release were investigated under similar conditions. Comprimates containing PVP and drug with particle size 1.75 μm (in lactose mixture) gave optimum results. These findings may open new ways of formulating a metronidazole tablet exhibiting improved drug - liberation, subsequently with a better bioavailability than the KUON^R-Tablet manufactured in Hungary.     

Effect of Particle Size and Excipients on the Dissolution Rate of Metronidazole from Solid Dosage Forms: I

Abstract

The use of metronidazole in the treatment of Trichomoniasis, Giardiasis, Amoebiasis and infections caused by anaerobic microbes has been well established. This communication outlines efforts made to design a metronidazole formulation with better absorption properties than the “KLION-Tablet”, currently manufactured by the Chemical Works of Gedeon Richter Ltd., Budapest, A relatively low solubility of the drug in water, and improper selection of vehicles contribute to low dissolution rate, hence limiting the absorption. Particle size reduction and the incorporation of lactose in the finer aggregating powder, showed increased dissolution rate.     

Effect of Particle Size and Excipients on the Dissolution Rate of Metronidazole from Solid Dosage Forms: II

Abstract

In-vitro dissolution tests were carried out with tablets prepared from different particle size ranges of metronidazole. Influence of tablet binding agents (Methylcellulose, polyvinyl pyrrolidone - (PVP), potato starch and gelatin) on the drug release were investigated under similar conditions. Comprimates containing PVP and drug with particle size 1.75 μm (in lactose mixture) gave optimum results. These findings may open new ways of formulating a metronidazole tablet exhibiting improved drug - liberation, subsequently with a better bioavailability than the KUON^R-Tablet manufactured in Hungary.     

Effect of Stearic Acid Particle Size on Surface Characteristics of Film-Coated Tablets

Abstract

Raw material specifications are vital for many excipients used in the manufacture of tablets. Stearic acid powder is widely used in the pharmaceutical industry as a tablet lubricant. This study shows that the variation in particle size of stearic acid not only affects die wall lubrication properties (ejection force) but also affects surface characteristics of film-coated tablets. A coarser grade of stearic acid can dislodge from tablet surfaces during the film-coating process leaving pit marks, whereas a finer grade of stearic acid (less than 100 mesh) results in film-coated tablets having very smooth surfaces. The mechanism of pitting on the tablet surface is described. A specification for stearic acid particle size to overcome this problem is suggested.     

分散剂用量对几种纳米氧化锆粉体尺寸表征的影响

本文研究了三种不同来源的纳米氧化锆粉体在尺寸表征中的影响因素．其中,加入的分散剂用量不同,测得的粉体颗粒尺寸有很大差别,不足或过量的分散剂影响粉体的颗粒尺寸分布．这种影响是通过改变粉体表面的电荷分布来实现的．超声时间长短是影响粉体尺寸表征的另一个重要因素．     

分级轮转速对粒径分布的影响

通过计算流体力学软件Fluent对FTW-350型涡轮空气分级机内部的分级流场进行数值模拟,根据模拟结果对不同分级轮转速时分级机内部流场的动态压力、湍动能和流动速度的分布特性进行对比分析;通过实验研究涡轮空气分级机中分级轮转速对粒径分布的影响,在每种分级轮转速时进行3种不同的加料速度实验,对激光粒度仪测得的分级产物的累积粒径、平均粒径、累积体积分布和粒径频率分布进行对比分析。结果表明:转速增加有利于分级流场的稳定,并且在转速较小时,增大分级轮转速有利于改善分级产物的粒径分布;分级轮转速变化对粒径分布的影响随着加料速度的增大不断减小。     

基于激光粒度仪测量油品喷雾粒径的方法研究

为了测量油品喷雾过程的雾化性能,通过对喷嘴雾化粒径的指标和雾化粒径测定方法的分析,利用激光粒度仪及粒径发生装置设计喷嘴雾化实验系统,并对实验系统的工作原理进行描述;在不同喷雾压力下测定煤基柴油特征平均粒径dv10、dv50、dv90、d[3,2]、d[4,3]数据。结果表明:柴油雾化过程分为形成阶段、扩散阶段、稳定阶段;喷雾压力越大,雾滴特征平均粒径dv10、dv50、dv90、d[3,2]、d[4,3]参数值越小,雾化效果越好,并且随着喷雾压力的增大,液滴雾化粒径减小的趋势变缓。     

Effect of Particle Size on Direct Compaction of Urea Fertilizer

The effect of particle size on compaction properties and characteristics of urea tablets manufactured from available urea granules (TG tablets) and ground urea powders (TP tablets) was investigated. The compaction properties, namely, plastic work, elastic work, friction work, and maximum ejection pressure were analyzed from the force-displacement profile of the compaction process. Five applied pressures ranging between 37.67 MPa and 188.35 MPa were used to compact the materials using a universal testing machine. Characteristics of the tablets tested were mechanical strength and the release of ammonium ion through dissolution test. The results demonstrated that TG tablets underwent high plastic work and elastic work but low friction work compared to the TP tablets. TG tablets released lower amount of ammonium ion compared to the TP tablets at almost all applied pressures, except at 75.34 MPa. This study provides a valuable data for evaluating the behavior of urea in the form of granules and powders during the compaction process as well as the suitability in choosing the form of raw material for the production of urea tablets.     

Effect of Amorphous Content on Dissolution Characteristics of Rifampicin

Rifampicin, one of the main first line anti-TB drugs, shows variable bioavailability in different marketed preparations and reasons cited include physiological, degradation, manufacturing/ processing, solid state, and bioavailability assessment procedure. Although the amorphous form of a drug is expected to exhibit higher solubility, the amorphous rifampicin has been reported to have a solubility disadvantage as compared to crystalline form II, which is used in marketed preparations. Amorphous form was generated and characterized by solid-state characterization techniques. Physical powder mixtures of form II with varying amounts of amorphous form were prepared, which were then subjected to solid-state characterization techniques and further evaluated for their dissolution behavior. Differential scanning calorimetry (DSC) scans show that area enclosed by integral of melting endotherm can be used for quantification of crystalline component, which can then be used to estimate amorphous content. No definite trend was evident in powder dissolution of mixtures that could implicate solubility difference of amorphous form. Intrinsic dissolution rate (IDR) results indicate that amorphous content has no effect on dissolution profiles of crystalline rifampicin.     

Effect of Particle Size Distribution of Calcined Diatomites on the Extinction Performance

Calcined diatomite was first investigated as matting agent for formulating high-performance coating. Jet milling and sieving or sedimentation methods were employed to obtain rational particle size distributions. It was found that the optimal size distribution of the particles with the diameters of D₁₀ = 2.54 µm, D₂₅ = 5.04 µm, D₅₀ = 9.74 µm, D₇₅ = 18.80 µm, and D₉₀ = 31.66 µm showed the best extinction performance, with the gloss and extinction being 2.9 and 3.3 and 32.6% and 50.7% determined at incidence angles of 60° and 85°, respectively.     

基于粒度仪的双枪喷涂雾化场的粒度的研究

目的 在保证喷涂雾化表征均匀性的前提下实现宽幅覆膜,提高覆膜的效率,以期得到均匀一致的大豆蛋白覆膜。方法 利用粒度仪测量不同干涉程度下的大豆蛋白液双枪喷涂雾化场的索特平均直径（Sauter Mean Diameter,SMD）,利用Spraylink软件处理粒度数据,得到粒度数据并对比。结果 双枪喷涂喷雾场的SMD随着液压的增大先增大后趋于平稳,随着气压的增大先减小后趋于平稳。当液压分别为0.08 MPa和0.16 MPa时,SMD基本不随偏转程度的变化而变化;当液压为0.24 MPa时,SMD随着偏转程度的增大而增大。双枪喷涂喷雾场的径向SMD从中心到边缘缓慢减小,在干涉区域内的轴向2点粒径基本相等。结论 当液压为0.08 MPa、气压为0.24 MPa、偏转角为0°时,SMD相对较小。文中的研究为实现宽幅覆膜奠定了理论基础。     

悬浮法成型UPR微粒的粒径及其分布

以不饱和聚酯(UPR)为原料,采用悬浮法制备粒径在120～250 μm的UPR微粒.考察了搅拌速度,油水比、分散剂及电解质对聚合物颗粒平均粒径及粒径分布的影响.