Follow
Tests carried out to verify and assure the quality and readiness of the filter membrane regarding the regulatory requirements are called filter integrity tests. If failed, shows that the filter is no longer re-usable, and also the previously filtered batch needs inspection. The machine that performs this task is called filter integrity machine. It needs to comply with Class B and Digital Devices under Part 15 of FCC regulations. These machines generally work on the principle of differential pressure.
The performance of any sterilizing filter is directly associated with the retention of bacterias below 0.22 µm. So, different size filters are used in sequence to reduce the load on a single small-sized filter. The first filter has a 0.45 µm size followed by 0.22 µm. Later, they get sterilized with steam for another batch process. These filters require filter integrity testing both before and after use if tested non-destructively.
The two cases to perform filter integrity testing are:
1. New Filters
2. Filters that require re-use
– In the first case, filter manufacturers themselves perform the testing along with certificates and documentation. If so, it is not mandatory for drugmakers to test new filters. However, they may do to have more confidence.
– Meanwhile, the second case often requires testing to check the intactness of the pore size of the membrane. Testing the differential pressure helps to assure the integrity of the filter. Agar plates re-check that no bacteria crossed the 0.22 µm filter.
