TY - JOUR
T1 - Resolving the rapid water absorption of porous functionalised calcium carbonate powder compacts by terahertz pulsed imaging
AU - Markl, Daniel
AU - Wang, Parry
AU - Ridgway, Cathy
AU - Karttunen, Anssi Pekka
AU - Bawuah, Prince
AU - Ketolainen, Jarkko
AU - Gane, Patrick
AU - Peiponen, Kai Erik
AU - Zeitler, J. Axel
PY - 2018/4
Y1 - 2018/4
N2 - 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.
AB - 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.
KW - Functionalised calcium carbonate
KW - Liquid imbibition
KW - Modelling
KW - Pharmaceutical tablets
KW - Porous media
KW - Terahertz pulsed imaging
UR - http://www.scopus.com/inward/record.url?scp=85040551698&partnerID=8YFLogxK
U2 - 10.1016/j.cherd.2017.12.048
DO - 10.1016/j.cherd.2017.12.048
M3 - Article
AN - SCOPUS:85040551698
SN - 0263-8762
SP - 1082
EP - 1090
JO - Chemical Engineering Research and Design
JF - Chemical Engineering Research and Design
ER -