Microcrystalline cellulose-water interaction--a novel approach using thermoporosimetry

Area of Science:

• Pharmaceutical Sciences
• Materials Science
• Physical Chemistry

Background:

• Microcrystalline cellulose (MCC) is a widely used excipient in pharmaceutical formulations.
• Understanding water interactions within MCC is crucial for optimizing drug delivery and manufacturing processes.
• The physical state of water significantly impacts the properties of wet granulation.

Purpose of the Study:

• To investigate the different water fractions present in microcrystalline cellulose (MCC) and silicified MCC wet masses.
• To determine the effect of granulation on these water fractions and the pore size distribution.
• To compare dynamic and isothermal step melting procedures in thermoporosimetry.

Main Methods:

• Thermoporosimetry combined with solute exclusion technique was employed.
• Analysis of both ungranulated and granulated MCC wet masses.
• Measurement of water fractions and pore size distributions in wet granules.

Main Results:

• Four distinct water fractions were identified: nonfreezing, freezing bound, free, and bulk water.
• Granulation led to a decrease in bulk water and an increase in freezing bound and free water.
• Granulated MCC wet masses exhibited a higher capacity for retaining water within particles.

Conclusions:

• Thermoporosimetry and solute exclusion provide valuable insights into MCC-water interactions.
• Granulation significantly modifies the physical state of water within MCC wet masses.
• The observed changes in water fractions during granulation are comparable to the effects of beating on cellulose fibers in papermaking.