- Different types of sterilization methods used in pharmaceutical industries.
- Moist heat, dry heat and membrane filtration methods are used in majority of companies.
- For example in case of moist heat sterilization there are three basic parameters we need to check during sterilization process.
- These are temperature, pressure and time.
- Any process would be called successful if all these parameters are met.
- So, to monitor these parameters in sterilization process we require chemical indicators.
- Chemical Indicator classifications to understand performance parameters and tolerances of various Chemical Indicators.
- The appropriate Chemical Indicator can then be used to obtain the information needed to determine the effectiveness of the sterilization process.
- Chemical Indicator for the sterilization process being monitored.
- ISO 11140 are classified in to six groups.
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Class -1
Process indicators (tape roll, label) use with individual indicative.
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Class -2
Specific test indicators (Bowie –Dick test).
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Class-3
Single variable indicators.
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Class-4
Multi variable indicators.
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Class -5
Integrating indicators.
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Class-6 Emulating indicators.
1.
Class-1
( Process Indicators):
- Process Indicators are intended for use with individual units (example. Packs, containers, bottles…etc.) to indicate that the unit has been directly exposed to the sterilization process and to distinguish between processed and unprocessed units.
- They shall be designed to react to one or more of the critical process variables.
- These tapes or labels are pasted on the each articles of the load which we sterilize.
- After completion of the sterilization cycles we can check that whether the load has attained required temperature or not by observing the change in colour of the indicator tape like some indicator tapes changes colour from light yellow to black or from light green to dark green.
- By these indicator tapes we can also differentiate
between processed and unprocessed load.
2.
Class-2
(Specific test indicators):
- Class 2 indicators are intended for use in specific test procedure as defined in relevent sterilizer / sterilization standards.
- Bowie-Dick type tests are specific tests used for equipment control to evauate the sterilizer performance.
- These indicators are used in specific test. Bowie dick test is the example of this class of chemical indicator.
- In Bowie dick test we check the heat penetration.
- If steam properly penetrate in the load then there will be uniform colour change of the chemical
- Indicator sheet which is used in this process otherwise if colour change is not uniform it means air pockets are present inside the load or autoclave chamber.
- So by this chemical indicator, we can assure that heat penetration is
properly talking place within the load.
3.
Class-3
(Single variable indicators):
- A single variable indicator shall be designed to react to one of the critical variable and is intended to indicate exposure to a sterilization process at a stated values (SVs) of the chosen variable.
- Single variable indicators may also be used for exposure control monitoring.
- Determine the a specific temperature was reached at a specific location in the sterilizer chamber.
4.
Class
-4 (Multi variable indicators):
- A multi- variable indicator shall be designed to react to
two or more of the critical variable and is intended to indicate exposure to a
sterilization process at the stated value (SVs) of the chosen variables.
5.
Class-5
(Integrating indicators):
- Integrating indicators are the most accurate of the internal chemical indicators.
- Integrating indicators are used for pack control monitoring.
- They can also be used as an additional monitoring tool
6.
Class-6
(Emulating indicators):
- Emulating indicators are cycle verification indicators which shall be designed to react to all critical variables for specified sterilization cycle.
- The sated values (SVs) are generated from the critical variables of the specified sterilization process.
- This is the most accurate class of chemical indicators which
met all the three critical parameters of the sterilization process.
- For more information on the ISO 11140 - 1:2005 and USP general chapter 1209.
- All these indicators are very important tool for the monitoring of the sterilization process so have a continue watch over each sterilization cycle with these chemical indicators.
