Effect of double ETO (Ethylene Oxide) Sterilization

[medwise]

Dear All,

We are doing a half-cycle validation of ethylene oxide sterilization. Our worst case device is made up of Makrolon (kind of plastic) and PVC tubing. This is a single use device and the areation period for acceptable EO residual is 20 days.

We are making 10 pallets for validation. Since this is a half cycle we wont be able to release it for sale. If we resterilise this product again after 20days can we sale this product or this 10 pallet is just a waste.

I understand that there would be some affect of EO gas if we resterilise it. Can anyone suggest me any studies or test method to determine the effect of resterilisation on the device? Is there any standard regarding this?

Any suggestions or advise will be much appreciated.

Thanks

Kindest Regards
Romit Singh

 

[MIREGMGR]

Re: Effect of double ETO Sterilization

Can anyone suggest me any studies or test method to determine the effect of resterilisation on the device? Is there any standard regarding this?

The standard is the same as applies to all other EtO sterilization issues, i.e. ISO 11135-1. If you want to be able to sterilize product twice when necessary, you need to encompass 2x sterilization within your validation process, including ISO 10993-7 residuals evaluation.

Once a 2x sterilization validation is achieved, future half cycle study product can be salvaged by re-sterilization. That however won't do you any good for the current process.

It's common to utilize accumulated scrap product, product process-setup output, physically similar but obsolete models, etc., to make up the bulk of a challenge load of this kind, so as to minimize the economic issues involved. Only the devices to be actually lab tested for verification must be actual current product. We keep challenge load stock in our warehouse for repeated use in re-validations.

 

[chris1price]

Hi

The main test after 2x exposure is going to be the effect on the EtO residuals and subsequent aeration time. If this is ok after 2x cycles, and the product is ok, then you should be able to argue that product exposed to just 1.5x cycles is ok as well.

Chris

 

[MIREGMGR]

The main test after 2x exposure is going to be the effect on the EtO residuals and subsequent aeration time. If this is ok after 2x cycles, and the product is ok, then you should be able to argue that product exposed to just 1.5x cycles is ok as well.

Product functionality validation/verification and sterile barrier packaging validation, both requiring accelerated aging backed up by real time aging, are parts of the sterilization validation process. Those can be significant issues in 2x validation, in addition to residuals.

I thought the implication was that a 2x validation did not yet exist for the product in question. I would agree that a 1.5x exposure would be supported by a 2x validation, but of course it wouldn't be supported by a 1x validation.

 

[medwise]

Hi Chris,

Please explain what does 2x means?

Regards
Romit

 

[medwise]

Re: Effect of double ETO Sterilization

Hi MIREGMGR,

I appreciate your immediate response.

Does this mean we have to do a full validation again in order to prove that we can resterilise our product from half-cycle?

Can you please explain what do you mean by 2x?

We did our full validation in 2007 and since then nothing has been altered. And we do our requalification anually. In full validation we did 3 half-cycle and a full cycle. Does 2x means that in the full validation we should do 6 half-cycle and 2 full cycle? I am confused.

Is there any other way out to use the product from half-cycle by doing any test? Having said that what if we wait for our product till the normal aeration time i.e.20 days and send it back for full sterilisation.

Thanks for your help.

Kindest Regards
Romit Singh

 

[harry]

Doesn't 2x = 2(times) = double ?

 

[Doug Tropf]

20 days of aeration seems exorbitant. We sterilize a variety of devices (kits mostly) and our longest aeration cycle is 72 hours.

 

[MIREGMGR]

Very extended aeration times aren't that uncommon in EtO sterilization of long tubing sets, particularly when the polymers in question have some degree of surface absorption of EtO but aren't fully EtO permeable so that molecular presence can escape through the bulk material to the outside. Tubing sets have very slow permeation through the free ends, no matter how many air changes/hour you run the aeration chamber at.

As Harry pointed out, "2x" means "twice" or "two times". Sorry to use slang.

The sterilization validation process involves not just establishing that you are achieving sterilization, but also that your sterile barrier packaging is correctly permeable without leaks or weaknesses, residuals are acceptable at time of release for shipping, and your product and packaging aren't degraded by the sterilization process either immediately or at the end of your claimed sterility period. (There are other elements of validation of your packaging, of course, but they're off topic for this thread.) Validating for "2x" means only that after the product is sterilized twice, it still passes all of the evaluations in addition to sterility.

 

[chris1price]

Hi

By 2x I mean running the same product through 2 full EtO cycles back to back. You would then check the product and packaging is acceptable and at the same time test for residuals to establish a double cycle aeration time.

This is common practice when using EtO to allow you to re-sterile product in case there is a sensor failure or other problem with the first cycle.

20 days aeration does sound long, but tubing can be difficult to fully sterilise and aerate.

Chris