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.     

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

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 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 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.     

Effect of Particle Size on the Dissolution Characteristics of Chlorthalidone

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.     

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.     

Correlation of the Particle Size Distribution Parameters with Sieving Rate Constant

Controlling the particle size distribution (PSD) of raw materials, intermediates, and end products is very critical to the success of the powder technology related processes. This study presents the evaluation of the sieving characteristics of some industrial minerals, namely, quartz, talc, and barite, and the establishment of possible correlations between the PSD and kinetics parameters. PSD of the ?600 µm fractions of quartz, talc, and barite minerals were plotted in Schuhmann mathematical approach. The size modulus (k_s) and distribution modulus (α_s) were obtained for each mineral. Then, sieving kinetics study was carried out for each mineral to determine optimum sieving time and sieving rate constant (k_k). Further, the size distribution parameters were correlated with the sieving rate constant values for those minerals. While distribution modulus (α_s) increases, size modulus (k_s), and average sieving rate constant values (k_k) decrease. The correlations were found to be k_s = ?293.52α_s + 730.87 and k_k = ?0.0041α_s + 0.0454. The results showed that near-mesh particles play important role in the overall kinetic process.     

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.     

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。     

乙草胺微囊悬浮剂的粒度及其分布

采用原位聚合脲醛树脂法制备乙草胺微囊悬浮剂,利用激光粒度仪、光学显微镜、扫描电子显微镜等研究剪切速率、芯材黏度及固化阶段搅拌速率等对乙草胺微囊悬浮剂粒度分布的影响。结果表明:乳化过程中,控制剪切速率不变,通过添加质量分数为6.25%的甲苯可以有效减小乳液的粒度;在固化阶段,选择600 r/min的搅拌速率能够减少微囊之间的粘连与破囊现象。     

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.     

Particle Size Determination of a Three-Component Suspension Using a Laser-Scattering Particle Size Distribution Analyzer

In this study, a rapid and accurate particle size determination method using a light-scattering particle size analyzer was developed to measure the particle size and size distribution of a suspension containing three solid components: clotrimazole, triamcinolone, and sarafloxacin, which have different refractive indices. To ensure that data represent the size distribution of the primary particles of the suspension, the optimal sonication prior to and during measurement was detemined. It was found that the results obtained using the average relative refractive index (RRI) of the three components agreed with the results obtained using three individual RRIs. In addition, the results from two analysts demonstrated good reproducibility of this method. The size distribution data of the suspension were also compared to those of the bulk drugs. The results showed that the median particle size of this three-component suspension is relatively close to that of clotrimazole, which accounts for 80% of solid particles in the suspension. Furthermore, the results obtained using the light-scattering technique were comparable to those obtained using a polarized light microscope equipped with an image analyzer, indicating acceptable accuracy of this technique.     

导叶式旋风管入口颗粒粒度分布对分离效率的影响

为深入研究导叶式旋风管的分离机理,用不同粒度分布的SiO2颗粒对分离总效率与粒级效率进行了对比研究。实验结果表明:入口颗粒的粒度分布不但对旋风管的分离总效率有影响,而且对粒级效率也有较大影响;不同粒径大小的颗粒在旋风管中的分离机理不同。     

Relationship Between Particle Size and Dissolution Rate of Bulk Powders and Sieving Characterized Fractions of two Qualities of Orthoboric Acid

We have carried out a study of the particle size distribution and aqueous dissolution rate of two commercially available qualities of orthoboric acid, labeled “crystal” (ABC) and “powder” (ABP). In a previous work, we have shown that the two commercial qualities of orthoboric acid chosen as model compound (“powder” and “crystal”) are related to the same crystal network in spite of their dvferent names. However, these two qualities have very different size particle distributions, as previously determined by sieving and confirmed by the present laser light scattering study. Dissolution testing is performed under sink conditions and show that the bulk ABC quality dissolves far more rapidly that the bulk ABP quality, For each quality, dissolution rates of four sieved particle size fractions (0-90 μm; 90-125 μm; 125-180 μm; 180-250 μm) were compared. Concerning the ABC quality, comparisons were also done with three other particles size fractions: 250-355 μm, 355-500 μm, and 500-710 μm. This study used the dQ/dt versus t profile. Dissolution profiles of the fractions enclosing particles with a size superior to 125 μm are very close. On the other hand, fractions enclosing particles with a size smaller than 90 μm present a different profile and a slower rate of dissolution.     

Relationship Between Particle Size and Dissolution Rate of Bulk Powders and Sieving Characterized Fractions of two Qualities of Orthoboric Acid

Abstract

We have carried out a study of the particle size distribution and aqueous dissolution rate of two commercially available qualities of orthoboric acid, labeled “crystal” (ABC) and “powder” (ABP). In a previous work, we have shown that the two commercial qualities of orthoboric acid chosen as model compound (“powder” and “crystal”) are related to the same crystal network in spite of their dvferent names. However, these two qualities have very different size particle distributions, as previously determined by sieving and confirmed by the present laser light scattering study. Dissolution testing is performed under sink conditions and show that the bulk ABC quality dissolves far more rapidly that the bulk ABP quality, For each quality, dissolution rates of four sieved particle size fractions (0-90 μm; 90-125 μm; 125-180 μm; 180-250 μm) were compared. Concerning the ABC quality, comparisons were also done with three other particles size fractions: 250-355 μm, 355-500 μm, and 500-710 μm. This study used the dQ/dt versus t profile. Dissolution profiles of the fractions enclosing particles with a size superior to 125 μm are very close. On the other hand, fractions enclosing particles with a size smaller than 90 μm present a different profile and a slower rate of dissolution.