Pore network within tablets structurally regulates sustained drug release from insoluble matrix tablets.

Area of Science:

• Materials Science
• Pharmaceutical Sciences
• Chemical Engineering

Background:

• Controlled and sustained-release formulations are crucial in drug delivery.
• The microstructure evolution and its impact on drug release in matrix tablets are not fully understood.
• Understanding structure-transport relationships is key for optimizing drug release profiles.

Purpose of the Study:

• To investigate the dynamic microstructure evolution of matrix tablets during drug release.
• To establish the relationship between the initial formulation structure and drug transport pathways.
• To provide microstructure-resolved insights into sustained-release mechanisms.

Main Methods:

• Synchrotron radiation X-ray microtomography (SR-μCT) was employed to visualize the internal structure.
• Pore network analysis was used to quantify structural characteristics and transport pathways.
• Potassium chloride (KCl) was used as a model drug in matrix tablets.

Main Results:

• Pore networks are directly influenced by the spatial distribution of drug crystals, not random.
• Initially isolated pore domains merge into a percolating network, facilitating drug transport.
• Increased diffusion distance is offset by enhanced network connectivity and transport area.
• The tablet membrane maintains structural integrity during the dissolution process.

Conclusions:

• Pore network evolution critically governs drug release from matrix tablets.
• The study introduces the structural diffusion index (SDI) to characterize pore network changes.
• This research provides a framework for designing advanced controlled-release formulations by regulating pore networks.