One of the most important processes in the manufacture of pharmaceuticals is sterilization, especially for products intended to be sterile. The success of this sterilization will have a direct impact on the safety, quality and ultimately health of the product(s) being manufactured. The use of Biological Indicators (BIs) is a preferred method for the pharmaceutical industry to verify that they are operating effectively and provide safe and efficacious products.
A Biological Indicator is a resistance microorganism that is used to challenge the conditions of that sterilization process to show that the sterilization procedure achieves its intended result. The use alone, of the BI, in the sterilization process, will not provide assurance that the sterilization process is effective; its performance characteristics must also be validated. This is a require in accordance with the Good Manufacturing Practices (GMP) that the regulatory agency has published, and validation of the Biological Indicator is integral to the sterilization assurance process.
They are used to confirm that conditions for sterilization are sufficient to kill resistant microorganisms. A typical biological indicator will consist of:
1. Microbial spores that have some degree of resistance.
2. A carrier material; i.e., strip, disc, ampoule, or suspension.
3. A protective packaging.
Because microbial spores are known to be very resistant to destruction, if a sterilization process successfully destroys the microbial spores, then this provides confirmation of the effectiveness of that sterilization process.
1. Confirmation of sterilization effectiveness.
2. Validation of sterilization cycles.
3. Routine monitoring.
4. Protection of patients.
5. Meeting regulatory requirements.
Unlike physical or chemical indicators, biological indicators provide direct microbiological evidence of a successful sterilization process.
The higher the D-value, the more resistance of the biological indicator.
- Effectiveness of the sterilization cycle
- Challenge level of indicator
- The specific organism is in the indicator
- The spore population is accurate
- The resistance characteristics are acceptable
- The method of recovery is reliable
- Sterilization process
- Organism type
- Acceptance criteria
- Testing Method
The objective of the protocol is to show that the organism is both suitable as a biological indicator and reliable.
Verification by perform the following verification tasks:
- Confirmation of organism strain used
- Confirmation of purity of the organism used in the biological indicator.
- Confirmation of the organism as per supplier certification.
This will ensure the use of the correct resistant biological indicator.
- Recovery of spores from the bio-indicator
- Performing serial dilutions
- Performing a microbial plate count
- Comparing microbial plate count to specification
All results must be within predefined acceptance limits.
To determine the D Value perform the following tests:
- Place the Bio indicators (biological indicators) in sterilization conditions for various time intervals.
- Recover surviving spores from Bio-indicators.
- Calculate a log reduction from the recovered spores.
- Calculate the D Value mathematically.
This will show that the Bio-indicator provides an adequate challenge to the sterilization process.
Survival Time: The minimal amount of time that an indicator can survive and still be functional.
Kill Time: The minimum amount of time that will result in all of the indicators (3) being destroyed.
This is done to demonstrate/conform that the sterilization cycle acts predictably regarding the performance of the indicator.
The following procedures will be followed:
- Incubation of the microorganisms in a suitable growth medium
- Verification of the presence of microbial growth
- Confirmation that the growth medium will support recovery of the microorganisms
If the recovery methods are inadequate, there is a risk of obtaining false-negative results
Validation methods will include:
- Verification of the temperature of the incubator
- Confirmation of incubation time
- Testing of growth media for suitability
Different microorganisms have different requirements for incubation.
The following procedure will be followed:
- Inoculate the growth medium with a low microbial population
- Incubate in accordance with defined conditions
- Observe the growth of the microorganisms
Successful growth of microorganisms indicates that the medium is acceptable for recovery of microorganisms.
The following documentation must be maintained:
- Validation Protocol
- Raw Data
- Test Results
- Calculations
- Final Report
Complete documentation will establish compliance with GMP (Good Manufacturing Practices).
Examples of the acceptance criteria:
- Microorganism identity verification (or correct microbe identification)
- Adequate spore count
- D-value within specified parameters
- Deliverable recovery of live organisms
- Expected numbers of survivors and killed organisms observed
If any of the above criteria are not met, it will require a full investigation into why.
- Variable spore counts
- Incorrect incubation conditions
- Inefficient recovery of organisms
- Contamination during testing
By ensuring proper planning is executed and aseptic technique is employed when performing the validation can reduce the incidence of the above issues.
Typical applications:
- Monitoring autoclave cycles
- Qualification of sterilizers
- Validation of loads
Routine use of BIs assists with controlling the process of sterilization through the continued verification of effective processing.
- a change in sterilization cycle
- a change in BI supplier
- a change in incubation method
- modification to the sterilizer
Performing a regular review will maintain ongoing reliability of BIs.
- scientific justification
- proper validation
- routine monitoring
- adequate documentation
Not having properly validated BIs could lead to regulatory observations during inspections.
- Use of certified biological indicators.
- Adhere to standard microbiological methods.
- Thoroughly validate recovery methods.
- Maintain complete records.
- Train staff properly.
Following these best practices will help ensure effectiveness and compliance.
Sterilization assurance in pharmaceutical manufacturing is dependent upon validating biological indicators. Validation of biological indicators demonstrates that they are trustworthy, robust, and appropriate for use as a monitoring tool for sterilization procedures.
Structured procedures for validation, with appropriate documentation, will allow pharmaceutical manufacturers to guarantee proper sterilization controls and have the regulatory support needed to demonstrate that validated biological indicators can provide confidence that sterilization methods are consistently giving you protection on both product quality and patient safety.
- If the sterilization cycle changes
- If the BI supplier changes
- If the testing method changes
What Exactly are Biological Indicators?
Biological Indicators consist of a known number of viable microorganisms that have been developed into a standardized format or preparation and possess a known degree of resistance to a particular type of sterilization technique.They are used to confirm that conditions for sterilization are sufficient to kill resistant microorganisms. A typical biological indicator will consist of:
1. Microbial spores that have some degree of resistance.
2. A carrier material; i.e., strip, disc, ampoule, or suspension.
3. A protective packaging.
Because microbial spores are known to be very resistant to destruction, if a sterilization process successfully destroys the microbial spores, then this provides confirmation of the effectiveness of that sterilization process.
Importance of Biological Indicators
Biological indicators are among the most accurate means to evaluate sterilization technique effectiveness as they determine the effectiveness of a sterilization process by providing definite evidence of microbial destruction. Biological indicators may be used for:1. Confirmation of sterilization effectiveness.
2. Validation of sterilization cycles.
3. Routine monitoring.
4. Protection of patients.
5. Meeting regulatory requirements.
Unlike physical or chemical indicators, biological indicators provide direct microbiological evidence of a successful sterilization process.
Types of Biological Indicators
Different types of Biological Indicators are needed for effective sterilization.1. Steam Sterilization Indicators
Steam sterilization is often performed using Geobacillus stearothermophilus spores. They are particularly resistant to the effects of steam.2. Dry Heat Sterilization Indicators
Dry heat sterilization systems are generally tested using Bacillus atrophaeus spores.3. Ethylene Oxide (ETO) Sterilization Indicators
Bacillus atrophaeus spores are also the preferred biological indicator for ETO sterilization.4. Hydrogen Peroxide Sterilization Indicators
Hydrogen peroxide sterilization is tested using biological indicators made specifically for that process; however, the indicators will contain spores that are specifically suited for vaporized hydrogen peroxide sterilization processes.Key Characteristics of Biological Indicators
The characteristics of biological indicators used to monitor the effectiveness of pharmaceutical sterilization processes must include:- Resistance to the sterilization method employed
- The ability to maintain a stable population of spores over time
- Consistent performance of the spore population
- Ability to easily recover spores following their exposure to the sterilization process
What is D-Value?
D-value is the period of time necessary under a certain context to assure that 90% of the microorganism population, or 1 log reduction, has been removed.The higher the D-value, the more resistance of the biological indicator.
D-value Importance
D-value can be used to establish:- Effectiveness of the sterilization cycle
- Challenge level of indicator
Validation of Biological Indicators
Validation of BI stresses that the BI is appropriate for their intended use and that they produce consistent results. Validation assures that:- The specific organism is in the indicator
- The spore population is accurate
- The resistance characteristics are acceptable
- The method of recovery is reliable
Why Validation is Necessary
Biological indicators (BIs) that are inaccurate or not reliable can lead to erroneous results. Consequently, this could cause:- Release of a non-sterile product
- Unnecessary rejection of the batch
- Non-compliance with regulations
Validation Procedure for Biological Indicators
Validation requires a structured procedure.Step 1. Define Scope and Objective
The protocol for validation must clearly define the following:- Sterilization process
- Organism type
- Acceptance criteria
- Testing Method
The objective of the protocol is to show that the organism is both suitable as a biological indicator and reliable.
Step 2. Verify Organism Identity
Verification activity for biological indicators must be performed to confirm the identity of the organism being used in the Bio-indicator device.Verification by perform the following verification tasks:
- Confirmation of organism strain used
- Confirmation of purity of the organism used in the biological indicator.
- Confirmation of the organism as per supplier certification.
This will ensure the use of the correct resistant biological indicator.
Step 3. Verify Spore Population
The Bio-indicator must contain the specified number of spores. The verification of spore population is accomplished by:- Recovery of spores from the bio-indicator
- Performing serial dilutions
- Performing a microbial plate count
- Comparing microbial plate count to specification
All results must be within predefined acceptance limits.
Step 4. Determine D-Value
The resistance of the biological indicator is evaluated using the D Value of the biological indicator.To determine the D Value perform the following tests:
- Place the Bio indicators (biological indicators) in sterilization conditions for various time intervals.
- Recover surviving spores from Bio-indicators.
- Calculate a log reduction from the recovered spores.
- Calculate the D Value mathematically.
This will show that the Bio-indicator provides an adequate challenge to the sterilization process.
Step 5. Survival and Kill Time Study
The purpose of this study is to determine indicator performance when subjected to SterilizationSurvival Time: The minimal amount of time that an indicator can survive and still be functional.
Kill Time: The minimum amount of time that will result in all of the indicators (3) being destroyed.
This is done to demonstrate/conform that the sterilization cycle acts predictably regarding the performance of the indicator.
Step 6. Recovery Method Validation
After the indicator is subjected to sterilization, it must be possible to recover any surviving microorganisms.The following procedures will be followed:
- Incubation of the microorganisms in a suitable growth medium
- Verification of the presence of microbial growth
- Confirmation that the growth medium will support recovery of the microorganisms
If the recovery methods are inadequate, there is a risk of obtaining false-negative results
Step 7. Verification of Incubation Conditions
Incubating in the correct conditions is vital to the successful growth of microorganisms.Validation methods will include:
- Verification of the temperature of the incubator
- Confirmation of incubation time
- Testing of growth media for suitability
Different microorganisms have different requirements for incubation.
Step 8. Growth Promotion Test
Growth medium used for recovery must provide adequate support for the growth of microorganisms.The following procedure will be followed:
- Inoculate the growth medium with a low microbial population
- Incubate in accordance with defined conditions
- Observe the growth of the microorganisms
Successful growth of microorganisms indicates that the medium is acceptable for recovery of microorganisms.
Step 9. Documentation & Report
All validation activities must be documented appropriately.The following documentation must be maintained:
- Validation Protocol
- Raw Data
- Test Results
- Calculations
- Final Report
Complete documentation will establish compliance with GMP (Good Manufacturing Practices).
Acceptance Criteria
The validation protocols must include objective-based acceptance criteria to evaluate the biological indicators.Examples of the acceptance criteria:
- Microorganism identity verification (or correct microbe identification)
- Adequate spore count
- D-value within specified parameters
- Deliverable recovery of live organisms
- Expected numbers of survivors and killed organisms observed
If any of the above criteria are not met, it will require a full investigation into why.
Common Challenges in BI Validation
While validating biological indicators, there are common challenges organizations can encounter:- Variable spore counts
- Incorrect incubation conditions
- Inefficient recovery of organisms
- Contamination during testing
By ensuring proper planning is executed and aseptic technique is employed when performing the validation can reduce the incidence of the above issues.
Routine Monitoring Using Biological Indicators
After the initial validation, BI's should be used on a routine basis to monitor sterilization cycles.Typical applications:
- Monitoring autoclave cycles
- Qualification of sterilizers
- Validation of loads
Routine use of BIs assists with controlling the process of sterilization through the continued verification of effective processing.
Revalidation Requirements
Triggers for biological indicator revalidation may include:- a change in sterilization cycle
- a change in BI supplier
- a change in incubation method
- modification to the sterilizer
Performing a regular review will maintain ongoing reliability of BIs.
Regulatory Expectations
Regulatory authorities expect that biological indicators should meet these requirements:- scientific justification
- proper validation
- routine monitoring
- adequate documentation
Not having properly validated BIs could lead to regulatory observations during inspections.
Best Practices for Biological Indicator Validation
Best practice recommendations for biological indicator validation are:- Use of certified biological indicators.
- Adhere to standard microbiological methods.
- Thoroughly validate recovery methods.
- Maintain complete records.
- Train staff properly.
Following these best practices will help ensure effectiveness and compliance.
Sterilization assurance in pharmaceutical manufacturing is dependent upon validating biological indicators. Validation of biological indicators demonstrates that they are trustworthy, robust, and appropriate for use as a monitoring tool for sterilization procedures.
Structured procedures for validation, with appropriate documentation, will allow pharmaceutical manufacturers to guarantee proper sterilization controls and have the regulatory support needed to demonstrate that validated biological indicators can provide confidence that sterilization methods are consistently giving you protection on both product quality and patient safety.
Frequently Asked Questions (FAQs) on Validation of Biological Indicator
Q1. What is the purpose of a Biological Indicator?
Answer: Biological Indicators/BI are sterile, commercially-manufactured, resistant spores that you (the healthcare provider) can use to demonstrate the effectiveness of sterilization, "Is my sterilization process successful?".Q2. What is the value of Biological Indicators?
Answer: They are scientifically proven, mail-order, and provide direct microbial evidence that the conditions used to sterilize an object worked.Q3. What are the Organisms Used and Why?
Answer: The two most common organisms that are used as Biological Indicators are Geobacillus stearothermophilus and Bacillus atrophaeus.Q4. Define D-Value?
Answer: The D-value is the time it takes to reduce the number of viable spores (microbial organisms) by 90% or the time period needed to achieve that effect (under controlled laboratory conditions).Q5. What is Biological Indicator Validation?
Answer: BI validation ensures the competing organism(s) within the BI are both a reliable and resistive/appropriate choice(s) and determination of the BIs are reliable.Q6. What is the Value of Recovery Validation?
Answer: Performed after exposure to a sterilizing cycle to ensure that live organisms can be accurately counted.Q7. Specify when Validation/Re-validation is required?
Answer: Revalidation is required:- If the sterilization cycle changes
- If the BI supplier changes
- If the testing method changes
Q8. What do Regulators Expect?
Answer: Validated biological indicators, proper documentation, and compliance with Good Manufacturing Practices (GMP).
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