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Pharmaceutical Powders (pharmaceutical + powder)
Selected AbstractsAgglomeration modeling of small and large particles by a diffusion theory approachAICHE JOURNAL, Issue 5 2009Alvaro Realpe Abstract The interaction particle-binder during the wet granulation process plays a major role in the agglomeration of particles. This interaction has been modeled by a force balance acting on the particle where the binder's viscous force increases the strength of liquid bridge and facilitates the particle agglomeration. In this work, agglomeration kernels based on Brownian movement approach of small particles in the binder layer, the size ratio between particles (monodispersed and polydispersed), and binder's viscous forces were considered to model the wet granulation process of pharmaceutical powders in a laboratory-scale high shear mixer. The assumptions of no-stationary and pseudostationary behavior were suitable to describe the growth kinetics of the two stages (fast and slow) observed. A volume ratio of 150 between large and small particles produces the most effective granulation growth. The developed kernels were tested simulating experimental data obtained from a high shear mixer. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Evaluation of a rotary tablet press simulator as a tool for the characterization of compaction properties of pharmaceutical productsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2010F. Michaut Abstract The Stylcam 100R, a rotary press simulator, was designed to simulate speed profiles of rotary tablet presses. Such a simulator was qualified by numerous laboratories and, actually, its ability to be used for studying the behaviour of powders under pressure should be examined. Then, the purpose of this work was to investigate the performances of the Stylcam 100R for characterizing the compaction behaviour and the tabletting properties of pharmaceutical powders. The compressibility of three pharmaceutical excipients (microcrystalline cellulose, dicalcium phosphate dihydrate and ,-lactose monohydrate) was studied. Four compression speeds were used on the compaction simulator. Force,displacement cycles were associated with two energy parameters, the specific total energy (Estot) and the specific expansion energy (Esexp). The mean yield pressure was calculated from Heckel's plots obtained with the in-die method. The diametral tensile strength of compacts was measured in order to evaluate mechanical properties. To evaluate the accuracy of all these parameters, a comparative study was carried out on an eccentric instrumented press. The values of energy parameters and tensile strengths of tablets are close between the eccentric press and the compaction simulator, whatever the compression speed on the latter. The mean yield pressure values obtained using the two presses are different. Finally, the Stylcam 100R seems to be a good tool for characterising tabletting properties of powders, except for the Heckel's model probably due to an unadapted equation of deformation and a lack of accuracy of the displacement transducers. Future improvements should allow correcting these two points. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2874,2885, 2010 [source] Thermal expansion of organic crystals and precision of calculated crystal density: A survey of Cambridge Crystal DatabaseJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 5 2007Changquan Calvin Sun Abstract True density is a physical property of both fundamental and practical importance to the study of pharmaceutical powders. True density may be calculated from crystal structure. However, precision of such calculated density is not well understood. Furthermore, thermal expansion properties of organic crystals have rarely been characterized. A survey of Cambridge Crystal Database is conducted to assess (1) precision of calculated crystal density from crystal structure; (2) thermal expansion properties of organic crystals. It is shown that calculated crystal density exhibits, on average, a relative standard deviation (RSD) of ,0.4%. It is found that crystal density generally increases linearly with decreasing temperature provided no phase change occurs. Slope of the line, termed thermal density gradient, of organic crystals ranges between 0.04 and 1.74 mg,cm,3,K,1 with an average of ,0.2 mg,cm,3,K,1. It is shown that majority polymorph pairs exhibit significantly different thermal expansion behavior and their density,temperature lines can cross. This likely contributes to the less than perfect prediction of relative stability of polymorphs at ambient temperature using the density rule. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 1043,1052, 2007 [source] Analysis of the surface energy of pharmaceutical powders by inverse gas chromatographyJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2002Ian M. Grimsey Abstract The behavior of pharmaceutical solids, during either processing or use, can be noticeably affected by the surface energetics of the constituent particles. Several techniques exist to measure the surface energy, for example, sessile drop, and dynamic contact angle measurements. Inverse gas chromatography (IGC) is an alternative technique where the powder surface is characterized by the retention behavior of minute quantities of well-characterized vapors that are injected into a column containing the material of interest. Recently published articles using IGC on pharmaceutical powders have ranged from linking surface energetic data with triboelectric charging to studying the effect of surface moisture on surface energetics. Molecular modelling has also recently been used to explore the links between IGC data and the structural and chemical factors that influence surface properties, thereby achieving predictive knowledge regarding powder behavior during processing. In this minireview, the reported applications of IGC in the analysis of pharmaceutical powders are summarized and the major findings highlighted. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:571,583, 2002 [source] Automated Digital Image Based Measurement of Boundary Fractal Dimension for Complex NanoparticlesPARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 1 2003Ramitha Wettimuny Abstract There is a growing realization that complex nanoparticles produced by combustion reaction, precipitation, and spray technology using supercritical fluids, are fractally structured. The boundary fractal dimension is linked to the flow, packing and consolidation dynamics of nanopowders. It also contains information on the formation dynamics of the nanoparticles produced by various methods. Extraction of the fractal dimension information embodied in the nanoparticle's fractal structure is hampered by the lack of automated characterization algorithms for processing images of particles. This paper describes an efficient algorithm for analyzing digitized images of fractally structured nanoparticles and presents a computer program that automates the procedure using digital image processing techniques. The program functionality is demonstrated and discussed using digital images of typical pigment, ceramic and pharmaceutical powders. [source] | ||||||||||