AAPS PharmSciTech

, Volume 15, Issue 1, pp 131–139 | Cite as

Influence of Starting Material Particle Size on Pellet Surface Roughness

  • Srimanta Sarkar
  • Bee Hwee Ang
  • Celine Valeria Liew
Research Article


The purpose of this study was to investigate the effect of pelletization aids, i.e., microcrystalline cellulose (MCC) and cross-linked polyvinyl pyrrolidone (XPVP), and filler, i.e., lactose, particle size on the surface roughness of pellets. Pellets were prepared from powder blends containing pelletization aid/lactose in 1:3 ratio by extrusion–spheronization. Surface roughness of pellets was assessed quantitatively and qualitatively using optical interferometry and scanning electron microscopy, respectively. Both quantitative and qualitative surface studies showed that surface roughness of pellets depended on the particle size of XPVP and lactose used in the formulation. Increase in XPVP or lactose particle size resulted in rougher pellets. Formulations containing MCC produced pellets with smoother surfaces than those containing XPVP. Furthermore, surface roughness of the resultant pellets did not appear to depend on MCC particle size. Starting material particle size was found to be a critical factor for determining the surface roughness of pellets produced by extrusion–spheronization. Smaller particles can pack well with lower peaks and valleys, resulting in pellets with smoother surfaces. Similar surface roughness of pellets containing different MCC grades could be due to the deaggregation of MCC particles into smaller subunits with more or less similar sizes during wet processing. Hence, for starting materials that deaggregate during the wet processing, pellet surface roughness is influenced by the particle size of the material upon deaggregation.


extrusion–spheronization filler particle size pelletization aid surface roughness 



The authors wish to acknowledge research funding support from GEA-NUS Pharmaceutical Processing Research Laboratory fund (N-148-000-008-001) and A*STAR SERC grant number 102 161 0049 (R-148-000-157-305).


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Copyright information

© American Association of Pharmaceutical Scientists 2013

Authors and Affiliations

  • Srimanta Sarkar
    • 1
  • Bee Hwee Ang
    • 1
  • Celine Valeria Liew
    • 1
  1. 1.GEA-NUS Pharmaceutical Processing Research Laboratory, Department of PharmacyNational University of SingaporeSingaporeSingapore

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