Understanding die fill variation during mini-tablet production

Hui Ping Goh, Paul Wan Sia Heng, Celine Valeria Liew

Research output: Contribution to journalArticleResearchpeer-review

21 Citations (Scopus)


Reproducibility of die fill during tablet production is critical to ensure consistent tablet drug content and mechanical attributes. In the production of mini-tablets, tablets smaller than 6 mm, achievement of uniform die fill is much more challenging. Powder flow is often associated with die fill accuracy but this relationship has not been well characterised especially for mini-tablets. In this study, flow properties of different types of granules were characterised. Mini-tablets of 1.8 and 3 mm diameters were prepared from the granules using a rotary press with multiple-tip compression tooling. A methodology was established to evaluate mini-tablet die fill variation within and across compaction cycles using data from compression roller displacement and mini-tablet weight. Both sizes of mini-tablets showed similar extents of inter-cycle weight variation that could be associated with granules’ inter-particulate friction. However, smaller mini-tablets had higher intra-cycle weight variation due to their narrower die orifices. Multivariate and univariate analyses suggested that gravity fill influenced intra-cycle weight variation of 3 mm mini-tablets while suction fill was associated with that of 1.8 mm mini-tablets. Possible differences in die fill mechanisms between the mini-tablet sizes were identified and this provided a better insight into die fill variations during the production of mini-tablets.

Original languageEnglish
Pages (from-to)279-286
Number of pages8
JournalInternational Journal of Pharmaceutics
Issue number1-2
Publication statusPublished - 20 Dec 2017
Externally publishedYes


  • Die fill
  • Mini-tablet
  • Multiple-tip tooling
  • Powder flow
  • Weight variation

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