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EO Sterilization Validation: Overkill with Benefits

By Courtney Lang, Study Director, EO Department, BS, RM(NRCM)

Ethylene oxide (EO) validation is conducted as part of a 510(k) or PMA submission. It validates the EO sterilization process as a whole and ensures that the process produces product that meets requirements for a sterility claim. The validation is specific to the product, loading configuration, cycle parameters and sterilization chamber.

EO validations are performed according to ISO 11135-1:2007, most commonly using the half-cycle approach of the overkill method. The half-cycle approach is conducted by performing a minimum of three half cycles and one full cycle, in the production vessel, using the established cycle parameters. The validation cycles are monitored using process challenge devices (PCDs) that have demonstrated greater resistance to sterilization than the device, as confirmed, in a relative resistance study. The ability of the sterilization process to inactivate the biological indicators (BIs), contained within the PCDs, demonstrates that the process meets requirements for a sterility claim.

Part of the validation consists of monitoring harmful residuals that may remain on the device after processing. The sterilant gas residue analysis determines the level of residual EO, ethylene chlorohydrin (ECH) and ethylene glycol (EG) on the device. The residual results must be below the required limits as established in ISO 10993-7, for the products intended use, to be considered safe for distribution.

Once the initial validation is completed, a requalification is to be performed annually to detect any inadvertent process changes. A requalification may also be necessary if any changes have been implemented that may affect the validity of the validation (i.e. changes to the device, manufacturing process, sterilization process, etc.).

Nelson Labs offers a variety of services to aide device manufacturers in all aspects of the validation process, from initiation to completion. This includes PCD and cycle development, and coordination of the validation with the contract sterilizer. Nelson Labs also offers services pertaining to maintaining the validation and routine production, such as requalification and lot release testing.