| Precipitated silica as flow regulator. | |
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MedLine Citation:
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PMID: 18595668 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Flow regulators are added to solid pharmaceutical formulations to improve the flow properties of the powder mixtures. The primary particles of the flow regulators exist in the form of huge agglomerates which are broken down into smaller aggregates during the blending process. These smaller aggregates adsorb at the surface of the solid's grains and thus diminish attractive Van-der-Waals-forces by increasing the roughness of the host's surface. In most cases amorphous silica is used as flow additive but material properties like particle size or bond strength influence the desagglomeration tendency of the agglomerates and thus the flow regulating potency of each silica. For some silica types we will show that the differences in their flow regulating potency are due to the rate and extent by which they are able to cover the surface of the host particles. Binary powder mixtures consisting of a pharmaceutical excipient and an added flow regulator were blended in a Turbula mixer for a defined period of time. As pharmaceutical excipient corn starch was used. The flow regulators were represented by a selection of amorphous silicon dioxide types like a commercial fumed silica and various types of SIPERNAT precipitated silica provided by Evonik-Degussa GmbH, Hanau, Germany. Flowability parameters of the mixtures were characterized by means of a tensile strength tester. The reduction of tensile strength with the blending time can be correlated with an increase in fragmentation of the flow regulator. |
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Authors:
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Anne-Kathrin Müller; Joanna Ruppel; Claus-Peter Drexel; Ingfried Zimmermann |
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Publication Detail:
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Type: Journal Article Date: 2008-05-28 |
Journal Detail:
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Title: European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences Volume: 34 ISSN: 0928-0987 ISO Abbreviation: Eur J Pharm Sci Publication Date: 2008 Aug |
Date Detail:
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Created Date: 2008-07-22 Completed Date: 2008-10-03 Revised Date: 2009-11-19 |
Medline Journal Info:
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Nlm Unique ID: 9317982 Medline TA: Eur J Pharm Sci Country: Netherlands |
Other Details:
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Languages: eng Pagination: 303-8 Citation Subset: IM |
Affiliation:
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Pharmaceutical Technology, Institut of Pharmacy and Food Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Chemical Precipitation Chemistry, Pharmaceutical Excipients / chemistry Particle Size Powders Rheology Silicon Dioxide / chemistry* Starch / chemistry Technology, Pharmaceutical / methods Tensile Strength |
| Chemical | |
Reg. No./Substance:
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0/Excipients; 0/Powders; 7631-86-9/Silicon Dioxide; 9005-25-8/Starch |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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