Resolving the rapid water absorption of porous functionalised calcium carbonate powder compacts by terahertz pulsed imaging

Research output: Contribution to journalArticleScientificpeer-review

Researchers

  • Daniel Markl
  • Parry Wang
  • Cathy Ridgway
  • Anssi Pekka Karttunen
  • Prince Bawuah
  • Jarkko Ketolainen
  • Patrick Gane

  • Kai Erik Peiponen
  • J. Axel Zeitler

Research units

  • University of Cambridge
  • Omya International AG
  • University of Eastern Finland

Abstract

Cost effectiveness, ease of use and patient compliance make pharmaceutical tablets the most popular and widespread form to administer a drug to a patient. Tablets typically consist of an active pharmaceutical ingredient and a selection from various excipients. A novel highly porous excipient, functionalised calcium carbonate (FCC), was designed to facilitate rapid liquid uptake leading to disintegration times of FCC based tablets in the matter of seconds. Five sets of FCC tablets with a target porosity of 45-65% in 5% steps were prepared and characterised using terahertz pulsed imaging (TPI). The high acquisition rate (15Hz) of TPI enabled the analysis of the rapid liquid imbibition of water into these powder compacts. The penetration depth determined from the TPI measurements as a function of time was analysed by the power law and modelled for both the inertial (initial phase) and Lucas-Washburn (LW, longer time Laplace- Poiseuillian) regimes. The analysis of the hydraulic radius estimated by fitting the liquid imbibition data to the LW equation demonstrates the impact of the porosity as well as the tortuosity of the pore channels on the liquid uptake performance. The tortuosity was related to the porosity by a geometrical model, which shows that the powder compact is constructed by aggregated particles with low permeability and its principal axis perpendicular to the compaction direction. The consideration of the tortuosity yielded a very high correlation (R 2 =0.96) between the porosity and the hydraulic pore radius. The terahertz data also resolved fluctuations (0.9-1.3Hz) of the liquid movement which become more pronounced and higher in frequency with increasing porosity, which is attributed to the constrictivity of pore channels. This study highlights the strong impact of a tablet's microstructure on its liquid penetration kinetics and thus on its disintegration behaviour.

Details

Original languageEnglish
Pages (from-to)1082-1090
JournalChemical Engineering Research and Design
Early online date2018
Publication statusPublished - Apr 2018
MoE publication typeA1 Journal article-refereed

    Research areas

  • Functionalised calcium carbonate, Liquid imbibition, Modelling, Pharmaceutical tablets, Porous media, Terahertz pulsed imaging

ID: 17360863