Dec 18, 2007

Sterlization finally resolved

I posted previously on failing a natural product sterility (NPS) test in a lot release using ethylene oxide (ETO) sterilization, and we finally have everything somewhat resolved, well really a couple weeks ago we did, but I've been too busy to post. An ISO 11135 lot release requires a half cycle, then biological indicator (BI) and NPS testing which must come back sterile, then a full cycle and further BI testing which comes back sterile. Residuals and pyrogen samples are taken from the full cycle. In the previous post I mentioned we failed the half cycle NPS testing.

After that we made our full cycle the half cycle and tested the full cycle samples for NPS and doubled the sterilization time for the rest of the samples (this still confuses some people at the company). Unfortunately those NPS samples failed as well, or more precisely one of forty samples failed on Day 7 of 14. All BI samples were negative. After much debate and me being the ever eager middleman between management and the sterilizer we decided to double our sterilization time once again then proceed. However, we had to start all over with the samples because we had used so many in testing.

While we were building more samples we looked into the NPS testing. The most notable thing was that we discovered we were using twice as many samples as required, 40 instead of 20. 20 samples assumes you use 10 samples with aerobic media and 10 samples with anaerobic media. You can even use 10 samples if you use the membrane method instead of using the two types of media on the device. For us, each sample was tested individually and had their own large media jar. We made a couple minor, mostly for show changes to how the test was conducted.

So we built more samples and re-sterilized at a fairly ridiculous length of time for the half cycle and twice this ridiculous length of time for the full cycle, the length of time is so high it borders on what the FDA considers non standard sterilization. Hopefully we can lower the time some in an actual sterilization validation in the future. Oddly (IMO), the sterilizer doesn't charge by time in the chamber, so sterilizing for 1 hour costs approximately the same as sterilizing for 5 hours.

It took much begging, but we actually managed to get these sterilized half and full cycle in less than three weeks. We passed all the required testing and we are finally on our way. There is another part to our product sterilization that I'll get back to when its done. Talking to the 510(k) consultant afterwards he said sometimes companies don't file with sterility test results. I'm not exactly sure what they're filing with then.

Since then we've been bench testing like crazy and I have been unsuccessfully trying to delegate tests, but it seems like we don't have any people that understand the product well enough to pass most tests on to. We did have a Dec 31 filing deadline, but its been moved. I am happy to say that my disposables part isn't the thing that is holding everything up despite a completely failed sterilization.


TaurusAngel said...

Hi, i am working in a medical device manufacturing company as a Sterilization Engineer, What i would like to know is how exactly the ETO sterilization chamber works? Thanking you in advance.

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