After the verification of the filtration process is completed, the product properties and process conditions should be evaluated periodically to determine whether it is necessary to be revalidated.

Main Point

At a minimum (but not limited to) the following should be evaluated to determine if revalidation is required:

1. The flow rate per unit area is higher than the verified flow rate

2. The filter pressure difference exceeds the verified pressure difference

3. The filtering time exceeds the verified time

4. Increase the filtration capacity without changing the filtration area

5. Filtration temperature change

6. Product prescription changes

7. Changes in filter sterilization conditions or sterilization methods

8. The filter manufacturer changes, the filter production process changes, or the membrane material or structural composition of the filter changes