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Powder flow in an automated uniaxial tester and an annular shear cell: a study of pharmaceutical excipients and analytical data comparison.
MedLine Citation:
PMID:  23043592     Owner:  NLM     Status:  Publisher    
Background: An automated version of uniaxial powder flow testing has recently been developed and there is a need for experimental data from pharmaceutical powders. Purpose: To compare the novel testing method with an annular shear cell using different pharmaceutical excipients. A particular aim was to gain an improved understanding of potential differences in the obtained flow results. Methods: Nine excipients were studied with both flow testers at different consolidation levels. Unconfined yield strengths were determined at similar major consolidation stresses. Finally, an anisotropic stress factor was calculated and the fractal character of the powders was assessed by means of image analysis in a rotating drum. Results: Data correlated generally well; however, the unconfined yield strength from uniaxial testing resulted mostly in lower values compared to annular shear cell testing. Differences were specific for the given excipients and mannitol demonstrated the highest discrepancy of measured flow parameters. The differences were first discussed by considering wall friction, anisotropy of forces, brittleness as well as the fractal nature of the powder surface. This heterogeneity of the powder as well as the anisotropy of forces was also found to be important for the relative flow index. Conclusions: The automated uniaxial method demonstrated faster and more reproducible flow testing as compared to an annular shear cell. Therefore, the new method has a high potential in pharmaceutics for example in the quality-control of powders.
Martin Kuentz; Peter Schirg
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-8
Journal Detail:
Title:  Drug development and industrial pharmacy     Volume:  -     ISSN:  1520-5762     ISO Abbreviation:  Drug Dev Ind Pharm     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-9     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7802620     Medline TA:  Drug Dev Ind Pharm     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
University of Applied Sciences and Arts Northwestern Switzerlandx , Institute of Pharma Technology, Gründenstr.40, CH-4132, Muttenz , Switzerland.
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