Macroindentation hardness measurement - Modernization and applications

Sarsvat Patel, Changquan Calvin Sun

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


In this study, we first developed a modernized indentation technique for measuring tablet hardness. This technique is featured by rapid digital image capture, using a calibrated light microscope, and precise area-determination. We then systematically studied effects of key experimental parameters, including indentation force, speed, and holding time, on measured hardness of a very soft material, hydroxypropyl cellulose, and a very hard material, dibasic calcium phosphate, to cover a wide range of material properties. Based on the results, a holding period of 3 min at the peak indentation load is recommended to minimize the effect of testing speed on H. Using this method, we show that an exponential decay function well describes the relationship between tablet hardness and porosity for seven commonly used pharmaceutical powders investigated in this work. We propose that H and H at zero porosity may be used to quantify the tablet deformability and powder plasticity, respectively.

Original languageEnglish (US)
Pages (from-to)262-267
Number of pages6
JournalInternational journal of pharmaceutics
Issue number1-2
StatePublished - Jun 15 2016

Bibliographical note

Funding Information:
C.S. thanks PhRMA Foundation for a Sabbatical Fellowship in Pharmaceutics ( 2014-2015 ) and Lundbeckfonden for partial support, which facilitated the completion of this manuscript.

Publisher Copyright:
© 2016 Elsevier B.V.

Copyright 2016 Elsevier B.V., All rights reserved.


  • Indentation
  • Plasticity
  • Powder technology
  • Tableting


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