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.     

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.     

激光粒度分析和筛分法测粒径分布的比较

分别采用筛分法和马尔文激光粒度分析仪两种方法对16种颗粒的粒径分布进行了测量。通过比较,发现两种测量手段得到的粒径分布结果存在较大的差异,马尔文激光粒度方法对颗粒粒径的测量结果偏小,受颗粒形状的影响很大;筛分法对微细颗粒的测量误差较大,但对大粒径颗粒的测量较为准确。通过对不同粒径段灰颗粒的显微照相,发现细颗粒的团聚是筛分法测量小颗粒结果偏小的主要原因。     

Dissolution Properties of Piroxicam Powders and Capsules as a Function of Particle Size and the Agglomeration of Powders

The poor dissolution characteristics of relatively insoluble drugs have long been a problem to the pharmaceutical industry. An example is piroxicam, a highly potent anti-inflammatory agent. In many countries, a large number of generic piroxicam products are available to the prescriber. The aim of this study was to investigate the cause of the dissolution problems experienced by manufacturers of generic piroxicam capsules. Two raw material batches and the dissolution properties of several piroxicam capsules were studied. Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD) results showed that the two raw material samples were identical with respect to polymorphic modification. The particles of powder 1 were smaller than those of powder 2, but the dissolution of powder 1 was much slower than that of powder 2. The dissolution results for the capsules showed a marked difference among different brands, with capsule C not meeting the USP tolerance. Adding surfactant to the dissolution medium increased the dissolution of both powder 1 and capsule C. Failure of powder 1 or capsule C to meet USP dissolution criteria could result in differences in product efficacy, as well as in potential side effects. Such observations should be taken into account along with other relevant considerations when decisions regarding the generic substitution of oral piroxicam products are made.     

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.     

Relationship Between Dissolution Rate and Bioavailability of Sustained-Release Ibuprofen Capsules

Dissolution studies of three marketed brands of ibuprofen sustained-release (SR) capsules were conducted on USP XIX dissolution apparatus 1, using buffers simulating the gastrointestinal tract (GIT) pHs. The products showed almost identical drug release pattern in dissolution studies. A single-dose crossover oral bioavailability study revealed statistically significant differences in C_max, T_max, AUC and percent bioavailability values among the SR products but no such differences are evident in the t_1/2a, K_a, t_1/2e, and K_e. Retard quotient values were used to evaluate the sustained-release nature of the products. Statistical moment parameters such as MRT, MAT, and MDT were related with the dissolution parameters. Statistically significant correlations were observed between MRT_{in vitro} and MRT_{in vivo} or MDT_{in vivo} T_50% and T_max; and T_90%, and C_max, or AUC¹²₀. The determination of MRT_{in vitro}, T_50%, and T_90%, may be useful as quality control parameters to which each batch of the ibuprofen SR products could be submitted.     

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.     

The Wetting and Dissolution Rate of Phenobarbitone Powders

Abstract

The wetting of phenobarbitone powders by solutions of sodium lauryl sulphate has been measured. Large changes in contact angle and adhesion tension occur at low surfactant concentrations followed by more gradual changes at higher concentrations. The dissolution rates of phenobarbitone from capsules reflect these changes showing that initially, dissolution is penetration rate limited.     

The Wetting and Dissolution Rate of Phenobarbitone Powders

The wetting of phenobarbitone powders by solutions of sodium lauryl sulphate has been measured. Large changes in contact angle and adhesion tension occur at low surfactant concentrations followed by more gradual changes at higher concentrations. The dissolution rates of phenobarbitone from capsules reflect these changes showing that initially, dissolution is penetration rate limited.     

废玻璃粉粒度分布与活性指数的灰色关联分析

经过不同研磨时间制得4组不同粒度的废玻璃粉,采用激光粒度分析仪测定废玻璃粉的粒度分布;采用灰色关联分析方法分析废玻璃粉粒度分布对活性指数的影响。结果表明:只有当废玻璃粉的粒径小于一定的值时才具有火山灰活性;对废玻璃粉活性指数起关键作用的粒径范围为6.414~20.710μm。     

Influence of Particle Size and Heating Rate on Decomposition of BC Dry Chemical Fire Extinguishing Powders

Pyrolysis of BC dry chemical fire extinguishing powders which are useful for Class “B” and Class “C” fires was conducted on a thermogravimetric analyzer with sample loading of 10–25 mg under dynamic air atmosphere. The effect of particle sizes (medium value 48.99, 27.24, 4.93 µm) and heating rates (10, 15, and 20°C min^?1) were examined. The pyrolysis kinetics of the samples was analyzed using a distribution activation energy model. It was found that the decomposition temperature decreased and the pyrolysis rate increased after the samples were milled. The agglomeration of particles during production did not have an appreciable influence on the pyrolysis process of the samples in our experimental conditions. The activation energy value was 77.13?219.78 kJ · mol^?1, 58.18?288.67 kJ · mol^?1, and 44.59?209.17 kJ · mol^?1 for the powder of particle size 48.99, 27.24, 4.93 µm. We should use micro powder in fire extinguishing.     

Changes in the Particle Size and Size Distribution During Compaction of two Pharmaceutical Powders with Dissimilar Consolidation Mechanisms

Five different size fractions (32–44 um, 53–63 urn, 75–90 um, 105–124 um, and 124–177 um) of heavy magnesium carbonate and Avicel PH102 were compressed into 12.5 mm diameter compacts by means of a hydraulic press at two pressures. Compacts of the 75–90 um fraction of both substances and their binary mixtures in three different ratios were also prepared at eight different pressures. The subsequent compacts were disintegrated by sonication, and the size of the resultant particles analysed. It was found that the median particle diameter of both powders and disintegrated compacts was affected by sonication time and by the amount of water present in the ultrasonic bath. However a standard method was established.

The results showed that the particle size of the disintegrated compacts might be affected by both the initial particle size and the differences in the consolidation mechanisms of these two substances. However changes in the particle size of the binary mixtures are dependent on the relative concentration and the consolidation mechanism of the components in the mixtures.     

筛分法和激光粒度法联合测定陆源碎屑岩粒度

用筛分法和激光粒度法联合测定陆源碎屑岩粒度,对激光粒度法的分析数据进行了校正,以保证两种方法的分析数据配套衔接.通过对比不同地质年代沉积岩的岩心校正前后概率累积频率曲线,校正后的曲线能更好地表征碎屑岩粒度的分布.对影响马尔文Mastersizer 2000激光粒度仪背景测量的进样器搅拌转速A、泵速B、超声强度C三个因子...     

筛分法测定钛精矿粒度分布

采用干式筛分法(机械筛分法)对粗粒级钛精矿进行粒度分布测定研究,利用统计置信区间表征各粒级粒度分布测定结果。结果表明:按筛分终点原则确定合理的筛分时间为11 min;在测定次数为12,显著性水平α为0.05的条件下,重复测定的各粒级粒度分布测定值用格拉布斯准则判定未发现离群值;在测定次数为12的条件下,各粒级粒度分布测定值的相对标准偏差为1.0%~4.5%,精密度和重现性满足筛分法粒度测定的要求。     

Relationship Between the pH of the Diffusion L'Ayer and the Dissolution Rate of Furosemide

Sodium bicarbonate and ascorbic acid, both highly water-soluble materials, were used to modify the initial dissolution rate of furosemide from tablet formulations in various dissolution media. The observed differences in the initial dissolution rates of the drug have been correlated with changes in the pH of the diffusion layer brought about by the diluents. The initial dissolution rate of furosemide was shown to be dependent on and controlled by the pH of the diffusion layer while the bulk exerted only a secondary effect by controlling the magnitude of the pH-change through its buffer capacity.     

Relationship Between the pH of the Diffusion L'Ayer and the Dissolution Rate of Furosemide

Abstract

Sodium bicarbonate and ascorbic acid, both highly water-soluble materials, were used to modify the initial dissolution rate of furosemide from tablet formulations in various dissolution media. The observed differences in the initial dissolution rates of the drug have been correlated with changes in the pH of the diffusion layer brought about by the diluents. The initial dissolution rate of furosemide was shown to be dependent on and controlled by the pH of the diffusion layer while the bulk exerted only a secondary effect by controlling the magnitude of the pH-change through its buffer capacity.     

An Innovative Device for Quantification of Percolation and Sieving Segregation Patterns-Single Component and Multiple Size Fractions

Segregation occurs during most particulate materials-related unit operations including mixing, conveying, discharging, filling, and compaction. A redesigned second-generation primary segregation shear cell (PSSC-II) was fabricated to simulate and quantify percolation and sieving mechanisms-based segregation. Several binary mixtures were tested to quantify the effect of size ratios and absolute size. The constituents of binary mixtures studied were spherical glass beads. Three binary size ratios, 4:1, 6:1, and 8:1, were tested. For a given size ratio, three different absolute coarse (710-850, 1000-1200, and 1400-1700 μm) to fine particle sizes were studied. The experimental results showed that the PSSC-II was capable of quantifying segregation potential for various materials. Several physical parameters such as segregation rate (SR), phase of segregation rate (PSR), distribution of segregation rate (DSR), maximum segregation rate (MSR), and normalized segregation rate (NSR) were created to describe the quantity of segregation to a certain level. It was concluded that: (1) Generally, the segregation rates increase with the increase in size ratio. A linear relationship between NSR and size ratio exists for glass beads (R² = 0.99). (2) Segregation rate also increases with absolute size. NSR increases linearly with absolute size for glass beads (R² = 0.99). Furthermore, a quantitative relationship exists between certain size ratios and segregation rates, i.e., while size ratio increased two-fold from 4:1 to 8:1, the NSR increased approximately six-fold. (3) The largest magnitude of the NSR occurred where both absolute size and size ratio were at their largest values. (4) The DSR for the binary mixture of glass beads was mainly concentrated in the center region of the shear box for larger size ratios such as 8:1 and 6:1, whereas, for smaller size ratios such as 4:1, the DSR is approximately uniformly distributed. (5) Both duration of lag phase (DLP) and duration of acceleration phase (DAP) decrease with increase in size ratios and in absolute sizes. The smaller the DLP and DAP, the larger the MSR.     

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.