Bioprocessing Practical Technologies for Lyophilization Understanding and Controlling Process

F reeze-drying or lyophilization is a process that removes water from a substance. This dehydration process is performed under vacuum while the substance is in a frozen state. Lyophilization technology is used to freeze-dry products such as biologicals, bacterial cultures, analytical chemistry moieties, and therapeutic molecules (e.g., antibodies, vaccines, drugs, and heat-sensitive proteins). Lyophilizing such products, particularly liquid formulations, vastly increases their shelf-life and stability. The lyophilization process comprises three essential steps: pretreatment, freezing, and drying. Pretreatment can be in the form of additives that stabilize the product, bulking agents that add mass to the product, or filtration to reduce volume and concentrate the product. The manner in which the product is frozen in the freezing step in large part determines the quality of lyophilization. Snap or fast freezing causes smaller pore size in the resultant product cake. This, however, decreases lyophilization efficiency as vapor has a more difficult path to exit the product. Slow freezing causes bigger pore size and results in better lypohilization efficiency. During drying, the primary drying step removes about 90% of the water. The remaining 10% bound water is removed during the secondary drying step.