Measuring the hydrophobicity of lubricated blends of pharmaceutical excipients

Marcos Llusa, Michael Levin, Ronald D. Snee, Fernando Muzzio

Research output: Contribution to journalArticle

23 Scopus citations


This paper discusses how the hydrophobicity of lubricated pharmaceutical formulations is affected by process variables such as shear rate and strain. Hydrophobicity is a critical property that affects the dissolution of powder formulations, tablets and capsules as well as the performance of tablet coating and granulation operations. In this paper, hydrophobicity is measured using a modified Washburn method. Results show that, in the absence of lubricant, the hydrophobicity of powders does not change substantially as a function of shear rate or strain. However, when magnesium stearate is present (concentrations studied here range between 0.5% and 2%), hydrophobicity increases as a function of strain, shear rate and lubricant concentration. Observed changes range over several orders of magnitude, readily explaining common "overlubrication" observations of delayed drug dissolution.

Original languageEnglish (US)
Pages (from-to)101-107
Number of pages7
JournalPowder Technology
Issue number1
StatePublished - Feb 20 2010

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)


  • Dissolution
  • Lubrication
  • Magnesium stearate
  • Wettability

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