The worst conditions in the actual production filtration process (interpretation: the higher the filtration temperature, the longer the filtration time, the larger the batch size, and the higher the pressure difference, the worst conditions are the worst conditions ) . Microbiologically challenge the product solution or product replacement solution to confirm the microbial retention capacity of the sterilizing filter.

Before carrying out the bacterial retention test, the activity test (survival test) is used to confirm the survival of the challenged microorganisms in the drug under the process conditions, so as to determine a reasonable bacterial challenge method.

Main Point:

1. Pseudomonas diminuta is the standard challenge organism for bacterial retention testing in sterile filtration validation. (Pseudomonas diminuta was selected as the standard challenge microorganism: a. It is a water-borne Gram-negative bacterium, which is widely representative of possible contaminating bacteria in the pharmaceutical production process; b. The size of the bacterium is very small, The diameter is about 0.3~0.4μm, and the length is 0.6~1.0μm; c. It is not pathogenic and can produce unicellular bacteria with reproducible size and shape relatively stably)

2. The microbial retention test usually includes three batches, at least one of which should be a filter membrane with low bubble point (low specification). (Interpretation: Among the three batches, two batches are randomly selected commercial normal specification filter membranes, and the third batch, the low bubble point filter membrane, is a specially produced filter membrane close to the bubble point limit. Membrane, which is manufactured with a slightly different process than normal specifications, represents the “worst case” for membrane filtration.)

3. Low bubble point requirement: within 10% of the standard bubble point value. (For example, assuming a filter, the standard bubble point value provided by the supplier is 50psi, and the bubble point of the low bubble point membrane is usually between 50-55psi. The lower the bubble point value, the more representative the worst condition.)

4. If the low bubble point filter membrane is not used in the verification, the bubble point value of the standard solution filter membrane/core used in the actual production must be higher than the minimum bubble point of the filter membrane actually used in the verification test value.

5. Set up a 0.45um parallel control. (Interpretation: 0.45μm In order to exclude the influencing factors of the experimental bacteria, if the downstream of the 0.45μm filter is sterile, the experimental bacteria do not meet the requirements.)

6. As much as possible, challenge microorganisms should be directly inoculated in the drug for bacterial challenge.

7. If an alternative solution is used for testing, provide reasonable data and explanations.

8. For the same family of products, that is, products with the same components but different concentrations, the method of challenging the limit concentration can be used for verification. (Interpretation: For the bacterial challenge experiment, the influencing factors are more complicated, including the influence of the product on the membrane, and the influence of the product on the size and shape of the bacteria. Therefore, there are usually products with different concentrations of the same components in high, medium and low levels. It is usually recommended to challenge the highest and lowest concentrations were tested.)