Radiation Sterilization: Product Bioburden and Verification Dose

WuXi AppTec supports the best practice of monitoring bioburden quantitatively and qualitatively to ensure the established radiation dose is valid.

For many medical device manufacturers, radiation sterilization is a critical element of sterility assurance programs. ISO 11137-1, ISO 11137-2 and ISO TS 13004 specify the requirements for establishing a sterilization dose based on known product bioburden, including quantity and resistance.

There are two approaches to radiation sterilization:

  • Knowledge of the bioburden, which is used to set the radiation dose
  • Selection of a sterilization dose of 25 or 15 kGy, or seven other pre-set doses, which are substantiated

Radiation sterilization validation uses a bioburden-based approach (unlike the overkill approach, which is frequently used for other modalities such as ethylene oxide and moist heat). This bioburden-based approach can present a challenge for manufacturers that have traditionally focused on bioburden quantity rather than bioburden type and resistance. Bioburden determination is an estimated value and typically varies over time. Best practice is to monitor bioburden quantitatively and qualitatively as an indication to ensure the established radiation dose is valid. To demonstrate this validity, a verification dose, which is a dose of radiation predicted to give a predetermined Sterility Assurance Level (SAL) of 10-1 or 10-2, is used.

A historical review of verification dose experiments conducted with WuXi AppTec over the past 10 years was performed. Findings from the review, which included positive sterility results with confirmed genus and species identifications, was presented in February 2018 at a peer-to-peer sterility sciences conference. Next week’s post will include a summary of the results and conclusions from this review.

For more information about best practices in radiation sterilization and how you can work with our experienced experts, contact us.

Contact Account Manager