A two-phase flow model simulating water penetration into pharmaceutical tablets
The purpose of the study is introduce a two-phase flow model to simulate water penetration into pharmaceutical tablets. This model was built by integrating Darcy’s law with the continuity principle, on the premise that water penetration was driven by capillary actions. Notably, this model concerned both the ingress of water (wetting phase) and simultaneous displacement of air (non-wetting phase). Due to the interference of the two fluids, the relative permeability and capillary pressure vary during water penetration.
Evolution of these parameters was incorporated in the model. Calibration of the model by water penetration experiments of the microcrystalline cellulose (MCC) tablet yielded an average pore radius of 42 nm. This derived result was corroborated by FIB-SEM analysis revealing the presence of extensive microporosity within MCC particles with an average radius of ∼30 nm. Further validation was achieved through close resemblance between the simulated and experimental water penetration profiles of MCC tablets possessing different porosities.
Overall, this study underscored the advantage of the two-phase flow model over single-phase flow models, by capturing the dependence of permeability and capillary pressure on water saturation. Therefore it holds promise for an enhanced description of water penetration into tablets.
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Materials
Microcrystalline cellulose (Avicel PH-101; abbr. MCC) was obtained from FMC Biopolymer (Pennsylvania, USA). Magnesium stearate (Ligamed MF-2-V-MB; abbr. MgSt) was provided by Peter Greven GmbH (Venlo, Netherlands).
Karthik Salish, Prajwal Thool, Yuri Qin, Phillip D. Yawman, Shawn Zhang, Chen Mao, A two-phase flow model simulating water penetration into pharmaceutical tablets, International Journal of Pharmaceutics, Volume 660, 2024, 124383, ISSN 0378-5173, https://doi.org/10.1016/j.ijpharm.2024.124383.
Read also our introduction article on Magnesium Stearate here:
