Gamma Irradiation - dose audit and source replenishment

htcoztrk

Involved In Discussions
Hello all!

I'm a QA Manager in a medical device manufacturing company. We were doing EO sterilization for our products but now we have started to manufacture a device that not suitable for EO but required Gamma irridation. Neither I or company has no past with gamma as we are using EO for many years.
We completed validation process (dose setting, bioburdens, sterility and dose mapping) cooperated with a testing institue. Validation done according to Method 1 as recommended by lab chief. Now it's been 6 months since we perform the validation and we will start production. So we did perform bioburden tests on 10 products from one batch.
I read ISO 11137 however there are two issues that not clear to me. :bonk: I'll appreciate if you can help me if you have any experience or knowledge on these issues.

1) What does 'dose audit' mean? Is it enough if we test the avarage bioburden level on 10 units of product? Do we need to irridate the products in verification dose and perform sterility every 3 months or only if bioburden level is high? I saw that standard asks for 110 products for dose audit so do we really use all these number of product for dose audits?

2) We received a letter from our irridation sterilizer and they are replenishmenting the irridation source. IQ and OQ will be revalidated by sterilizer. However I wonder if replenishment of source is effecting our PQ validation? Is it enough if we perform only dose mapping or do we need to repeat all PQ process?

Thank you in advance for your helps. :thanks:
 

chris1price

Trusted Information Resource
Hi, I'll try to answer your questions, however i recommend reading section 10.2 of 11137-2 very carefully.

The dose audit can be thought of as a verificaton that nothig has changed in the product or processes. For Method 1, you select 110 pieces. you perform bioburden on 10 pieces. If the results are ok, sterilise the remaining 100 at the verification dose and test for sterility. You are allowed up to 2 positive results. The standard explains what to do if you get positive results.

Yes this has to be done every quarter. Once you have good data, the period can be increased to 12 months - take a look at 11137-1 section 12.1.3.2

This is one of the major issues with Method 1, testing 110 pieces every quarter can get expensive and time consuming. a VDMax method only uses 20 pieces.

When they change the radiatoin source, you should only need to redo the dose mapping. I do not think there is any need to do PQ or other tests.

Chris
 

htcoztrk

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Thank you for your replyChris. I'll check again carefully your reffered clauses of standard.

Meanwhile I have another question that I think you may have an answer. We have two product sterilized by gamma. Since the materials are different we performed two validation. I already completed bioburden test for 10 units from a batch and determined the avarage level for both of them. However it's been 40 days since product 1 and 20 days since product 2 and I did not send out any goods for irridation&sterility testing because I was thinking bioburden is enough. But we released some batch of goods because average bioburden levels was appropriate. Do I need to initiate a recall?
 

isolytical

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In today's regulatory environment the concept of continuous validation replaces periodic validation. There is an FDA guide that explains the current thinking.
 

htcoztrk

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In today's regulatory environment the concept of continuous validation replaces periodic validation. There is an FDA guide that explains the current thinking.

Thank you for your reply. I look into few guaidance from FDA however I couldn't find any date about this concept. Do you have any link or document in your hand? I'll appreciate if you can share it with me.
 

chris1price

Trusted Information Resource
Whether or not you perform a recall is a decision for your company and the regulatory climate you operate in (US, EU, etc). I would perform a risk assessment looking at the validation, the sterilisation batch data and the bioburden and asses the risks involved; together with getting the products on test and looking at the results.

Hopefully, the issue is just that you are not following ISO11137 (a regulatory risk) and not that you have a risk of non-sterile product.

If you decide not to, you should document the decision and have a CAPA or deviation in place.

Chris
 

htcoztrk

Involved In Discussions
Whether or not you perform a recall is a decision for your company and the regulatory climate you operate in (US, EU, etc). I would perform a risk assessment looking at the validation, the sterilisation batch data and the bioburden and asses the risks involved; together with getting the products on test and looking at the results.

Hopefully, the issue is just that you are not following ISO11137 (a regulatory risk) and not that you have a risk of non-sterile product.

If you decide not to, you should document the decision and have a CAPA or deviation in place.

Chris

Thank for your suggestion Chris. Would you perform the sterilisation audit simultaneously to sterility testing on sterilisation batch? Also should I consider to get sample from each batch that have been irridated since today for sterility testing or sampling from a representative batch?

-Hatice
 

mpfizer

Involved In Discussions
Hi, I'll try to answer your questions, however i recommend reading section 10.2 of 11137-2 very carefully.

The dose audit can be thought of as a verificaton that nothig has changed in the product or processes. For Method 1, you select 110 pieces. you perform bioburden on 10 pieces. If the results are ok, sterilise the remaining 100 at the verification dose and test for sterility. You are allowed up to 2 positive results. The standard explains what to do if you get positive results.

Yes this has to be done every quarter. Once you have good data, the period can be increased to 12 months - take a look at 11137-1 section 12.1.3.2

This is one of the major issues with Method 1, testing 110 pieces every quarter can get expensive and time consuming. a VDMax method only uses 20 pieces.

When they change the radiatoin source, you should only need to redo the dose mapping. I do not think there is any need to do PQ or other tests.

Chris
Hi,

I have a few questions on the above standard

if we have an average bioburden count of 15.6 cfu and the corresponding dose as per table 9 is 7.6kGy and if the average bioburden remains 15.6 or lower then why do we need to irradiate ten pcs. and check for sterility every quarter ? I am aware the standard says so but it does not make sense. Even if the bioburden count goes up to 1000cfu it would still be ok is that not right

we use VD MAX 25 where it is supposed to kill 1000 cfu , our bioburden count has never gone beyond 20 cfu.

Am i missing something ?

michelle
 
Last edited:

planB

Super Moderator
Michelle,

the purpose of the dose audit is to demonstrate that your current bioburden, which is defined as being both the number and resistance of micro-organism, is still under control and equivalent to the bioburden you determined during your initial validation. Since seasonal effects may play a role, the standard requires you to perform this activity quarterly.

Note that ISO 1137-2 offers you the possibility to switch to annual dose audits in case you have passed four consecutive quarterly dose audits (you will still have to determine bioburden quarterly though).

Hope this helps,
 
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