Biomedical subjects
Publications and source records attributed to B Selmeczi.
The authors prepared potassium aspartate matrix tablets in combination with polyvinyl chloride. The physical parameters were measured and the dissolution rates were determined. During the in vitro release rate experiments, it was determined that the dissolution kinetics obey both zero order and Higuchi diffusion model order kinetics.
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Direct compression of phenylbutazone is possible only with addition of excipients of several kinds, because its material properties are unfavourable. It is necessary to use besides disintegrant glidant, lubricant and antistatic agents too. The authors investigated the influence of two microcrystalline cellulose binders (Avicel and Heweten) for the pressability of phenylbutazone and on properties of the tablets, respectively. It was determined the physical parameters of the tablets and the dissolution characteristics of the active ingredient. It has been found, that Heweten optimized the exactness of dosage of the tablets as well as resulted in a faster dissolution than Avicel. Therefore, Heweten proved to be the more suitable binder.
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When the pressing force increased in the examined system, so did the mechanical firmness of the tablets. A logarithmic connection exists between the pressing force and the compression strength and between the pressing force and the porosity, while the connection between the pressing force and the abrasion loss was a connection of power-function. The changing of the pressing force don't alter significantly the disintegration time of the tablets and the dissolution rate of the drug. However there is a considerable difference between the dissolution rate of the sulfathiazolee-powder and that of the tablets. The binders used in the pressing process were surface-active, therefore they accelerated the dissolution by moistening the surface of the sulfathiazol crystals.
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Experimental studies on the effect of various micronized celluloses (Avicel PH 101 and Heweten 40) on the compressibility and the dissolution of sulphathiazole showed that the binding power of Heweten 40 is inferior to that of Avicel PH 101, whereas the mechanical strength of the tablets conforms to specifications. Referring to the dissolution rates, it can be said that the use of Heweten 40 is more advantageous.
The authors prepared a spray-dried sulphathiazole product consisting of hollow pellets, the drug being in the form of its metastable modification I (melting point, 200 degrees C). On the basis of force-time diagrams and of current parameters relative to the elasto-plastic deformability of substances intended for tabletting, the compression behaviour of the spraydried product was compared with that of sulphathiazole (modification I) tempered at 180 degrees C for 150 min. Scanning-electron-microscopic studies on tablet surfaces offered further insight into the compressibility of the spraydried product.
The authors performed scanning-electron-microscopic studies to investigate the texture of sulphathiazole tablets. This method permitted to demonstrate the texture-forming effect of micronized celluloses used as dry binding agents. The differences in dissolution rate are interpreted.
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The authors studied the alterations of the texture and of the physical properties of Furosemid tablets, which are prepared with the aid of hydroxypropylcellulose mucilage, that occur during storage. Klucel MF mucilage proved to be a very good binding agent. Though the film bursted on drying during storage, by which the pore volume of the tablets increased, the mechanical strength remained almost unchanged. The cause of this is the formation of solid bridges.