Factors Influencing Product Residuals

B.1 General Guidance

The guidance provided here assists in the uniform implementation of sterilization requirements, ensuring conformity with specified standards such as ISO 11135.

B.2 Sterilization Process Considerations

B.2.1 General Overview

To properly analyse residuals in EO sterilized devices, it is vital to recognize parameters affecting residual content. Understanding EO kinetics allows for “worst-case” representative analysis within product families.

B.2.2 Material Composition

Materials vary in their ability to absorb and release EO. Materials with free chloride ions may significantly increase ECH formation. Accurate analysis requires sampling based on both composition and device size.

B.2.3 Packaging Barriers

Packaging density and the number of layers act as barriers to aeration. Consideration of the sterilization container or pallet density is essential for consistent results.

B.2.4 Sterilization Cycle Parameters

Key factors include humidity, gas concentration, dwell time, temperature, and vacuum type. For controlled processes, the 95% upper confidence limit helps establish routine aeration times.

B.2.5 Aeration & Seasonal Variation

Aeration efficiency depends on temperature, air flow, and load configuration. Best practice involves placing samples in the worst-case pallet location (cold spots) during validation.

B.2.8 Repeat Sterilization

While EO residuals are generally not significantly impacted by multiple cycles, re-sterilization must be qualified. Testing of samples after double or triple exposure ensures comparable safety profiles.