Principle of Lyophilization
Lyophilization is based on the principle of sublimation. Sublimation is the change of phase from solid to a gas without passing through a liquid state. This sublimation is the effect of the applied vacuum on the system.
Key parameters of the recipe may include:
- Shelf Temperature
- Product Temperature
- Chamber Pressure
- Primary drying
- Secondary Drying
Definitely, these recipes should comply with process validation requirements. Sometimes these recipe parameters may change from time to time based on the process dynamics and hence may require time to time verification.
Before initiating the Lyophilization process, Cleaning in Place, Pressure Leak Test, and Sterilization in Place cycles are carried out to ensure the system is ready to process.
Critical Aspects for Lyophilization
1. Critical Quality Attributes (CQAs)
These attributes include physical, chemical, or biological characteristics required to ensure the desired product quality.
Examples of Lyophilization CQAs:
- Appearance
- Moisture Content
2. Critical Process Parameters (CPPs)
Critical Process Parameters define how the process interacts with the product.
Examples of Lyophilization CPPs:
- Temperature of Freezing the product
- Primary Drying temperature and pressure (vacuum)
- Secondary Drying temperature and pressure (vacuum)
3. Critical Material Attributes (CMAs)
In order to manufacture quality products, attributes determine the criticality of the properties of the materials.
Examples of Lyophilization CMAs:
- Heat transfer capability of the shelves
- Product and Eutectic temperature
- Product structure
- Conductivity of water vapors
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