Characterization and Utilization of Acid-modified Rice Starches for Use in Pharmaceutical Tablet Compression
| Hlavní autori: | , , , |
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| Médium: | Článok |
| Jazyk: | angličtina slovenčina |
| ISSN: | ISSN 0038-9056 |
| On-line prístup: | http://www.viks.sk/chk/star_10_03_464_475.doc |
| Abstrakt: | Summaries. Acid modified, agglomerated starches offer specific advantages as fillers in production of pharmaceutical tablets. Spray drying can improve processing of tablet mixtures significantly. In order to investigate prerequisites in utilization of rice starch, non-waxy and waxy types were partially hydrolyzed in 6 % (w/v) HCI solution at room temperature for varied length of time to obtain rice starches with increased crystallinity (so-called crystalline rice starches). Scanning electron micrographs of native and highly crystalline starches were used to study the morphological changes and to suggest the mode of acid attack during hydrolysis. Exo-corrosion distributed over the surface of acid-modified waxy rice starch (AWRS) was observed after 192 h of hydrolysis. In contrast, the surface of acid-modified rice starch (ARS) remained unchanged at 192 h of acid hydrolysis. The amylose content and the median particle size (diameter) were reduced with increasing hydrolysis time. It was found by X-ray diffraction that the relative crystallinity of acid-modified starches at >95% relative humidity was clearly increased with prolonged hydrolysis time. For studying tablet properties spherical agglomerates of the native and acid modified starches were directly compressed at 4 kN to obtain tablets. Crushing strength and disintegration time of tablets increased with relative crystallinity. In contrast, tablet friability was reduced. Concerning tablet functionality, the crystalline starches were positioned in overlapping ranges between the common commercial tablet fillers (micro-crystalline cellulose, pregelatinized starch and lactose, respectively). Conclusions. As could be expected from a previous study [5], long-term hydrolysis with 6 % hydrochloric acid at room temperature resulted in serious changes in structure of granular rice starch (ARS) and waxy rice starch (AWRS). The acid attack resulted in decreases in amylose content and median particle size while relative crystallinity was increased. The water molecules present in starch granules promoted the rearrangement of starch molecules to form lamellae, and thus increased the relative crystallinity. The higher ordered structure of acid-modified starches used as fillers in tablet compression resulted also in more pronounced crushing strength and produced longer disintegration time, which contrasted with friability of the tablets. The highly crystalline and spherically agglomerating granules of the produced starch modifications demonstrated substantial improvements in functional properties and could therefore be employed as alternative tablet fillers in the relevant pharmaceutical industry. In summary, it could be concluded that relative crystallinity proved to be an important factor in tablet compression with agglomerated crystalline rice starch. Because of the economic advantage that can be derived from the investigated data, modified rice starches - non-waxy and waxy ones - offer an interesting potential for application as tablet fillers. |
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| ISSN: | ISSN 0038-9056 |
