A primary drying model-based comparison of conventional batch freeze-drying to continuous spin-freeze-drying for unit...

Area of Science:

• Pharmaceutical Technology
• Chemical Engineering
• Process Intensification

Background:

• Conventional batch freeze-drying is time-consuming for unit doses.
• A novel continuous spin-freeze-drying technology has been developed.
• Mechanistic modeling is crucial for optimizing freeze-drying processes.

Purpose of the Study:

• To compare conventional batch freeze-drying with continuous spin-freeze-drying.
• To develop and validate mechanistic primary drying models for both methods.
• To analyze and compare key process outputs like drying endpoint and temperature profiles.

Main Methods:

• Development of mechanistic primary drying models for batch and spin-freeze-drying.
• Experimental determination of input parameters (e.g., R_p, K_v, P_tot).
• Model-based comparison and experimental validation of process parameters and outcomes for model formulations.

Main Results:

• Spin-frozen formulations exhibited lower dried product layer resistance (R_p) than batch-frozen ones.
• Spin-freezing increases surface area and reduces dried layer thickness, leading to shorter drying times.
• Both mechanistic models accurately predicted primary drying endpoint and product temperature, with spin-freeze-drying showing faster kinetics.

Conclusions:

• Continuous spin-freeze-drying offers significantly reduced primary drying times.
• The technology maintains excellent cake structure and appearance.
• Mechanistic modeling is effective for optimizing and validating spin-freeze-drying processes.