Sterility Test Validation Note

It is important to determine if the test article that will be tested for sterility contains elements that will interfere with the growth of microorganisms within the growth media used for the assay. This validation testing is commonly referred to as a Bacteriostasis/Fungistasis (B/F) test. The validation test is typically required only once for a given sample type, provided that no additional changes to the source, product, formulation or manufacturing process occurred. However, validation testing could be performed on a periodic basis to confirm that no significant changes have occurred to the product or process that may affect the sterility assay results. MDS offers Sterility testing and Sterility test validation (B/F test). These testes can be performed individually or concurrently. At the client's discretion, once the sterility test is completed, the post-sterility-test samples can be used for the validation testing to avoid the use of additional samples

Sample Requirements by Test Article Type

• Cell & Virus Bank Testing
  Cell and virus banks manufactured under cGMP conditions require sterility testing be performed per the appropriate test methods outlined in the pharmacopeias and the 21 CFR 610.12. Neither the USP, EP nor 21 CFR 610.12 provide sampling requirement guidelines for cell and virus banks. However, ICH Q5D "Derivation and Characterization of Cell Substrates Used for the Production of Biotechnological/Biological Products" states that sterility testing will be performed on individual containers. It also states that 1% of the bank or no less than 2 containers will be tested. This recommendation has become a standard industry practice.
  
  
• Unprocessed Bulk Testing (For Protein and Virus Products)
  Within the biotherapeutics industry "Unprocessed Bulk" has many other descriptions, including cell/viral harvest, clarified cell/viral harvest, end of production cells or cells at the limit of in vitro cell age. Although the pharmacopeias and 21 CFR 610.12 do not reference or provide sterility guidelines for these sample types, the FDA documents ""Points to Consider in the Characterization of Cell lines Used to Produce Biologicals" (1993) and "Points to Consider in the Manufacture and Testing of Monoclonal Antibody Products for Human Use" (1997) do reference the need for sterility or bioburden testing on each unprocessed bulk lot. These two documents reference the 21 CFR 610.12 for guidelines on the appropriate sterility test methods to use. Since there is no reference in the pharmacopeias or 21 CFR 610.12 specifically related to unprocessed bulk material, no sampling guidelines are available either. However, industry practice is to use the sampling guidelines stated for bulk drug substance as detailed in the 21 CFR 610.12. Thus 10 mL/media (for a total of 20 mL) is recommended for sterility testing of unprocessed bulk material.
  
  
• Bulk Drug Substance (BDS) Testing
  Sterility testing is required on each manufactured BDS lot. Sampling requirements for Bulk Drug Substance is defined in 21 CFR 610.12, which states that no less than 10 mL will be tested. It is not clear if that is meant for each media or if the amount is to be split into the two test media. Industry practice has taken a conservative approach and 10 mL of BDS is tested in each media. Thus a total of 20 mL is required for sterility testing.
  
  
• Final Drug Product (FDP) Testing
  Sterility testing is required on each manufactured FDP lot. Sampling requirements for final drug product are provided in the pharmacopeias. The following tables outline the requirements as stated in the current USP.

Batch Size	Minimum Number to be Tested in Each media
100 or less	10% or 4 containers, whichever is greater
101 – 500	10 containers
>500	2% or 20 containers, whichever is less
Bulk– Up to 4 containers	Each container
5 – 50	20% or 4 containers, whichever is greater

  

For information regarding available sterility assays or to discuss the sterility test method most appropriate for your sample type, please contact us services@mds-usa.com