Authors:

Chi-En Huang

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About Paper:

Lyophilization, or freeze-drying, is essential for producing stable pharmaceutical products with long shelf lives at room temperature. However, optimizing the process remains a challenge due to its inefficiency, cost, and variability. This study focuses on comparing two methods for measuring mass transfer resistance (Rp) in lyophilization, aiming to make the fitting process more accessible and efficient for new users, since lyophilization processes are often designed by professionals without an engineering background. The first method uses a similar approach to LyoPRONTO, an existing tool that includes freezing and primary drying calculators, a design-space generator, and a primary drying optimizer. It calculates heat transfer from shelf to product, using experimentally measured temperatures, and subsequently determines Rp directly from experimental measurements by solving relevant heat and mass transfer equations, then employs a curve fit to give a smooth functional form for Rp. The second approach assumes a functional form for Rp, solves model equations without measurements, and adjusts tuning parameters so that model temperatures match experimental temperatures as closely as possible. Preliminary results and experience indicate that the first method is sensitive to early-time behavior which may not be well-described by the model equations, so the second method can improve the reliability and robustness of Rp measurements. Comparing these methods for representative cycles, we evaluate their accuracy and efficiency in predicting Rp. By documenting and making the better method more accessible, this research addresses inefficiencies in the lyophilization process, guiding the development of more efficient protocols and reducing time and cost. Keywords: Lyophilization; Freeze Drying; Mass Transfer; Heat Transfer; Primary Drying

Source:

Purdue University / 2024

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Co-authors:

Chi-En Huang