title: Continuous direct tablet compression: effects of impeller rotation rate, total feed rate and drug content on the tablet properties and drug release.
abstract: BACKGROUND
  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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: School of Pharmacy, University of Eastern Finland , Kuopio , Finland.
authors.forename: Maiju A
authors.initials: MA
authors.lastname: Järvinen
authors.forename: Janne
authors.initials: J
authors.lastname: Paaso
authors.forename: Marko
authors.initials: M
authors.lastname: Paavola
authors.forename: Kauko
authors.initials: K
authors.lastname: Leiviskä
authors.forename: Mikko
authors.initials: M
authors.lastname: Juuti
authors.forename: Fernando
authors.initials: F
authors.lastname: Muzzio
authors.forename: Kristiina
authors.initials: K
authors.lastname: Järvinen
mesh_terms: D000082:Acetaminophen / Q000737:chemistry*; D018712:Analgesics, Non-Narcotic / Q000737:chemistry*; D001331:Automation; D002482:Cellulose / Q000737:chemistry*; D055598:Chemical Phenomena; D003102:Colloids; D004339:Drug Compounding; D005079:Excipients / Q000737:chemistry*; D005387:Finland; D006244:Hardness; D007700:Kinetics; D055595:Mechanical Phenomena; D008958:Models, Molecular; D011786:Quality Control; D012822:Silicon Dioxide / Q000737:chemistry*; D012995:Solubility; D013229:Stearic Acids / Q000737:chemistry*; D013607:Tablets; D013678:Technology, Pharmaceutical; D013718:Tensile Strength
chemical_list: D018712:Analgesics, Non-Narcotic; D003102:Colloids; D005079:Excipients; D013229:Stearic Acids; D013607:Tablets; D000082:Acetaminophen; C031183:stearic acid; D012822:Silicon Dioxide; D002482:Cellulose; C109691:microcrystalline cellulose