A two-phase flow model simulating water penetration into pharmaceutical tablets.

Area of Science:

• Pharmaceutical Science
• Fluid Dynamics
• Materials Science

Background:

• Understanding water penetration into pharmaceutical tablets is crucial for drug dissolution and stability.
• Existing models often simplify fluid interactions, neglecting the complex interplay between water and air phases.

Purpose of the Study:

• To introduce and validate a novel two-phase flow model for simulating water penetration into pharmaceutical tablets.
• To incorporate capillary action, relative permeability, and capillary pressure dynamics into the model.
• To compare the two-phase model's performance against single-phase models and experimental data.

Main Methods:

• Integrated Darcy's law with the continuity principle to model two-phase flow (water and air).
• Incorporated the evolution of relative permeability and capillary pressure as functions of water saturation.
• Calibrated the model using water penetration experiments on microcrystalline cellulose (MCC) tablets.
• Validated results with FIB-SEM analysis of MCC particle porosity.

Main Results:

• The model successfully predicted water penetration profiles in MCC tablets.
• Calibration yielded an average pore radius of 42 nm for MCC, consistent with FIB-SEM (∼30 nm).
• The two-phase model demonstrated superior accuracy over single-phase models by capturing saturation-dependent parameters.

Conclusions:

• The developed two-phase flow model provides a more realistic simulation of water penetration into tablets.
• The model's ability to account for dynamic changes in permeability and capillary pressure enhances predictive power.
• This approach offers significant potential for optimizing tablet formulations and manufacturing processes.