Designing an Ethylene Oxide Sterilization Process

[ahmed.bpharm]

Dear forum Members,

Ethylene Oxide Sterilization Process is complex process and not very simple as mentioned in guidelines and standards. We have validated our process on following parameters;

1) Temperature of Chamber: 65.
2) Humidity of Chamber: 60 -70 %.
3) Exposure Time: 8 hrs.
4) EO gas Admission Temp: 30-40.
5) EO gas Conc: 400 mg / L.
6) Pre-Vacuum: -40 KPa.
7) De-gassing: -40 KPa.
8) Aeration Cycle: 1 hr.

We are using EO-Cross Check chemical indicators to monitor sterilization parameters and SGM Bacillus atropheus 106 for microbiological monitoring.

We are facing now-a-days problem in achieving color change in chemical indicators. Is there any seasonal effect on EtO sterilization Process as our problem started in rainy days.

Expertise in EtO sterilization validation are required for help.


Ahmed Zafar.

 

[Stijloor]

Dear forum Members,

Ethylene Oxide Sterilization Process is complex process and not very simple as mentioned in guidelines and standards. We have validated our process on following parameters;

1) Temperature of Chamber: 65.
2) Humidity of Chamber: 60 -70 %.
3) Exposure Time: 8 hrs.
4) EO gas Admission Temp: 30-40.
5) EO gas Conc: 400 mg / L.
6) Pre-Vacuum: -40 KPa.
7) De-gassing: -40 KPa.
8) Aeration Cycle: 1 hr.

We are using EO-Cross Check chemical indicators to monitor sterilization parameters and SGM Bacillus atropheus 106 for microbiological monitoring.

We are facing now-a-days problem in achieving color change in chemical indicators. Is there any seasonal effect on EtO sterilization Process as our problem started in rainy days.

Expertise in EtO sterilization validation are required for help.


Ahmed Zafar.

Any comments/suggestions for Ahmed?

Thank you!

Stijloor.

 

[Ajit Basrur]

Did you look at our existing threads on same subject ? If not, pl scroll to the bottom of the page for related links.

 

[somashekar]

Dear forum Members,

Ethylene Oxide Sterilization Process is complex process and not very simple as mentioned in guidelines and standards. We have validated our process on following parameters;

1) Temperature of Chamber: 65.
2) Humidity of Chamber: 60 -70 %.
3) Exposure Time: 8 hrs.
4) EO gas Admission Temp: 30-40.
5) EO gas Conc: 400 mg / L.
6) Pre-Vacuum: -40 KPa.
7) De-gassing: -40 KPa.
8) Aeration Cycle: 1 hr.

We are using EO-Cross Check chemical indicators to monitor sterilization parameters and SGM Bacillus atropheus 106 for microbiological monitoring.

We are facing now-a-days problem in achieving color change in chemical indicators. Is there any seasonal effect on EtO sterilization Process as our problem started in rainy days.

Expertise in EtO sterilization validation are required for help.


Ahmed Zafar.

At the same time what has been your result from the microbiological monitoring ?
That it started in your rainy days is an observation but this system being a tightly closed loop, I do not envisage an effect due to weather. There could be problems in your EO cross check chemical indicator, its shelflife or your storage conditions of them.
Please do come back with more information and try making a change in your EO cross check chemical indicator to find if the indicator itself is an issue.

 

[ahmed.bpharm]

Dear Somashekar,

First of all thanks for reply, I confirmed the EO cross check chemical indicators by sending them to another competitor and in their sterilizer, all indicators changed their colors according to the standard with less EO concentration in less exposure time.

Recently i have increased my exposure time, results were improved over all but color change is not up to the standard. If temperature of gas admission matters, i have tried both EO / CO2 gas temperature up to 45 degree Celsius and also up to 11 degree Celsius but both have not improved color change.

Apparently EO gas penetration seems the issue, because 30-40 % indicators changes their color but other 70 % remains dull. Before 15 days the chemical indicators were changing their color routinely and accurately but all of sudden in 2 - 3 days the results came poor.

I have tried all the parameters, i.e. applying deep shallow pre-vacuum upto -80 KPa, Controlling flow rate in between 140- 150 L/min, Pre-heating in chamber, Increasing chambers temperature, by increasing and decreasing relative humidity, increasing exposure time and last by decreasing load density and inner spaces between cartons. Nothing is giving any hope for improvement.

Any engineering solution will be highly appreciated after my process parameters.

Thanks,

Ahmed Zafar.

 

[Qara123]

Apparently EO gas penetration seems the issue, because 30-40 % indicators changes their color but other 70 % remains dull. Before 15 days the chemical indicators were changing their color routinely and accurately but all of sudden in 2 - 3 days the results came poor.

Are the dull indicators randomly distributed across the load or do they tend to be concentrated at a certain location?

Q

 

[ahmed.bpharm]

Dear Q;

Well all the indicators placed at different locations in sterilizer chamber are dull but in some cycles 2-3 locations were identified where indicators changed their color as per standard while other 12 location distributed across whole sterilizer were same dull.

Today we have tried another experiment in which we placed open chemical indicators i.e. not blistered with syringes in unit cartons to check the penetration across two barriers which are outer master carton and inner unit cartons. Whole indicators changed their color equally and upto the standard, which finished my doubt about the penetration of EO /CO2 mixture from large master carton and smaller unit carton. The only thing which remains is now blister paper and poly film the last but not least barrier.
In the light of above experiment, we have decided to place some open blisters of syringes in master carton without unit carton hence reducing one barrier, secondly we pasted some blistered indicators outside the large master cartons to verify the penetration through blister paper and poly film.

hope that the cause of least penetration is due to blister paper and poly film.

Other questions in mind are some process parameters such as ; Chamber temperature, Chamber humidity, Steam pulses, Pressure of Steam, Pre-Heating time, Temperature of EO gas heat exchanger, Flow of EO gas, Pre-Vacuum to evacuate air from the cartons, Exposure time after gas completion, De-gassing and aeration cycles to reduce the EO residues. Some one having command on EO sterilizer will be highly appreciated if guide me through the above said parameters, ?I shall share my parameters as well.

Thanks for all the replies,


Ahmed Zafar.

 

[somashekar]

Your blister paper is made to permit penetration. However if you resort to printing on this paper any product information, then it will add to reduced levels of penetration. Hope that your printing (if any) is still keeping about 70% clear minus the sealing widths. Are you certain that there is penetration also through polyfilm ?