A Radiation Sterilization Validation test determines the appropriate radiation sterilization dose for a product that requires a sterile label claim. It incorporates bioburden testing, a bioburden recovery efficiency test, a sublethal radiation dose (verification dose), a test of sterility, and method suitability (bacteriostasis/fungistasis) testing.

If a sterile label claim is required and the sterilization method will be radiation, a validation is required to determine the appropriate sterilization dose. Nelson Labs has vast experience providing validations for complex or unique products, or products which cannot handle large doses of radiation. Allowing for a more broader scope of products to be tested on. The testing complies with the radiation sterilization standard ANSI/AAMI/ISO 11137 and technical specification ANSI/AAMI/ISO 13004.

Similar to the Ethylene Oxide Sterilization method, one of the benefits of radiation sterilization testing is that it employs a cold gas sterilization process. Low temperature sterilization protects heat sensitive materials that cannot be exposed to high temperatures such as plastics, preventing destruction of the product. The radiation sterilization process also utilizes the terminal sterilization method which allows sealed medical devices to be processed while they are fully packaged.

Requirements of radiation validations and quarterly dose audits are provided in the ANSI/AAMI/ISO 11137 standard series.

Gamma irradiation is a commonly used method for sterilizing medical devices, and ISO 11137 provides guidelines for validating the radiation sterilization process. Here are key considerations for the gamma irradiation validation of medical devices in accordance with ISO 11137:

Biological Indicator (BI) Placement:

Place biological indicators (BIs) at critical locations on the medical device. BIs contain a known number of highly resistant microorganisms and serve as a challenge to the sterilization process. Monitor the BIs to confirm the effectiveness of the gamma irradiation.

Dosimetry System:

Implement a dosimetry system to measure and control the radiation dose delivered to the medical devices. This includes using dosimeters strategically placed throughout the load to ensure uniform dose distribution.

Dose Mapping:

Conduct dose mapping studies to ensure uniform radiation exposure throughout the entire product load. This is particularly important for large loads or loads with complex geometries to ensure that all areas receive the intended radiation dose.

Bioburden Assessment:

Determine the bioburden of the medical device, which is the population of viable microorganisms on the device before sterilization. This information helps establish the initial microbial load that the sterilization process must effectively eliminate.

Bioburden Reduction Studies:

Conduct bioburden reduction studies to determine the effectiveness of the gamma irradiation process in reducing the bioburden to an acceptable level. This may involve conducting validation runs with actual production units.

Dose Setting:

Establish the appropriate dose of radiation necessary to achieve the desired sterility assurance level (SAL). The SAL is typically expressed as a probability of survival, such as 10^-6, indicating a one in a million chance of a non-sterile unit.

Routine Dosimetry:

Implement routine dosimetry procedures during routine gamma irradiation cycles to ensure that the delivered dose remains consistent over time.

Validation Runs:

Perform validation runs using production-size batches of medical devices. Monitor and record critical parameters during these runs, and collect samples for bioburden testing and BI testing.

Dose Verification:

Verify the radiation dose delivered to the medical devices during the validation runs using dosimetry data. Ensure that the actual dose matches the intended dose.

Routine Monitoring:

Implement routine monitoring of the gamma irradiation process through ongoing bioburden assessments, BIs, and other relevant measures. Regularly review and record critical parameters during routine sterilization cycles.

Documentation:

Maintain comprehensive documentation of the gamma irradiation validation process, including protocols, results, and any deviations observed during the studies.

Requalification:

Requalify the gamma irradiation process when there are changes to the device design, manufacturing process, or sterilization conditions. Periodic requalification may also be necessary to ensure continued process effectiveness.

Product Compatibility:

Consider the impact of gamma irradiation on the materials and functionality of the medical devices. Perform compatibility studies to ensure that the sterilization process does not adversely affect the device's performance.

Regulatory Compliance:

Ensure that the gamma irradiation validation process complies with relevant regulatory requirements, such as those outlined in FDA guidance documents and international standards.

ISO 11137 provides a comprehensive framework for the validation of gamma irradiation processes. Manufacturers must carefully follow these guidelines, conduct thorough validation studies, and maintain ongoing monitoring to consistently achieve the required level of sterility assurance.

Applicable Standards

*ANSI/AAMI/ISO 11137
*ANSI/AAMI/ISO 13004