Continuous direct tablet compression: Effects of impeller rotation rate, total feed rate and drug content on the tablet properties and drug release

Maiju A. Järvinen, Janne Paaso, Marko Paavola, Kauko Leiviskä, Mikko Juuti, Fernando Muzzio, Kristiina Järvinen

Research output: Contribution to journalArticle

28 Scopus citations


Context: Continuous processing is becoming popular in the pharmaceutical industry for its cost and quality advantages. Objective: This study evaluated the mechanical properties, uniformity of dosage units and drug release from the tablets prepared by continuous direct compression process. Materials and methods: The tablet formulations consisted of acetaminophen (3-30% (w/w)) pre-blended with 0.25% (w/w) colloidal silicon dioxide, microcrystalline cellulose (69-96% (w/w)) and magnesium stearate (1% (w/w)). The continuous tableting line consisted of three loss-in-weight feeders and a convective continuous mixer and a rotary tablet press. The process continued for 8min and steady state was reached within 5min. The effects of acetaminophen content, impeller rotation rate (39-254rpm) and total feed rate (15 and 20kg/h) on tablet properties were examined. Results and discussion: All the tablets complied with the friability requirements of European Pharmacopoeia and rapidly released acetaminophen. However, the relative standard deviation of acetaminophen content (10% (w/w)) increased with an increase in impeller rotation rate at a constant total feed rate (20kg/h). A compression force of 12kN tended to result in greater tablet hardness and subsequently a slower initial acetaminophen release from tablets when compared with those made with the compression force of about 8kN. Conclusions: In conclusion, tablets could be successfully prepared by a continuous direct compression process and process conditions affected to some extent tablet properties.

Original languageEnglish (US)
Pages (from-to)1802-1808
Number of pages7
JournalDrug Development and Industrial Pharmacy
Issue number11
StatePublished - Nov 1 2013


All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmaceutical Science
  • Drug Discovery
  • Organic Chemistry


  • Acetaminophen
  • Content uniformity
  • Continuous direct tablet compression
  • Continuous powder mixing
  • Crushing strength
  • Dissolution
  • Tablet mechanical properties

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