Microstructure of calcium stearate matrix pellets: a function of the drying process

Area of Science:

• Pharmaceutical Sciences
• Materials Science

Background:

• Drying is a critical pharmaceutical process often underestimated for its impact on drug product properties.
• Calcium stearate (CaSt) is utilized as a matrix former in drug delivery systems.

Purpose of the Study:

• To investigate the influence of different drying techniques on the microstructure of ibuprofen-loaded CaSt pellets.
• To correlate microstructural changes with in vitro drug dissolution profiles.

Main Methods:

• Pellets were prepared using wet extrusion and spheronization with ibuprofen and CaSt.
• Drying was performed using desiccation, fluid-bed drying, and lyophilization.
• Microstructural analysis (porosity, specific surface area) and in vitro dissolution testing were conducted.

Main Results:

• All drying methods increased pellet porosity and specific surface area.
• Fluid-bed drying temperature influenced specific surface area, with lower temperatures yielding higher values.
• In vitro dissolution profiles showed a nonlinear relationship with the specific surface area.

Conclusions:

• The drying conditions strongly dictate the microstructure (porosity, pore size, specific surface area) of CaSt pellets.
• Microstructural modifications achieved through drying directly impact ibuprofen dissolution behavior.