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

M.A. Järvinen (Corresponding Author), Janne Paaso, M. Paavola, K. Leiviskä, Mikko Juuti, F. Muzzio, K. Järvinen

Research output: Contribution to journalArticleScientificpeer-review

28 Citations (Scopus)


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 8 min and steady state was reached within 5 min. The effects of acetaminophen content, impeller rotation rate (39–254 rpm) and total feed rate (15 and 20 kg/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 (20 kg/h). A compression force of 12 kN 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 8 kN. 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
Pages (from-to)1802-1808
Number of pages6
JournalDrug Development and Industrial Pharmacy
Issue number11
Publication statusPublished - 2013
MoE publication typeA1 Journal article-refereed



  • acetaminophen
  • content uniformity
  • continuous direct tablet compression
  • continuous powder mixing
  • crushing strength
  • dissolution
  • tablet mechanical properties

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