module 11 usp 1229 sterilization of compendial articles and usp … · 2021. 1. 18. · sterility...

USP <1229> Sterilization of Compendial Articles and USP

<1211> Sterility Assurance

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Sterility assurance for a lot/batch of product does not come from passing the tests in USP <71> Sterility Tests

A Reminder of the Challenge At Hand

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Probability of Passing the Sterility TestContamination Rate vs Sample Size

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Sterility assurance can be established only through the use of adequate sterilization cycles and subsequent aseptic processing, if any, and adherence to appropriate current good manufacturing practice. USP Chapters <1211>

Sterilization and Sterility Assurance of Compendial Articles and USP <1229> Sterilization of Compendial Articles address this

How Do You Gain Assurance of Sterility?

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Probability:

“The sterility of a lot purported to be sterile is therefore defined in probabilistic

terms, where the likelihood of a contaminated unit or article is acceptably remote.”

Another Reminder

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The generally accepted sterilization assurance level (SAL) is 10-6 microbial survivor probability or lower, i.e., assurance of no more than one chance in one million that viable microorganisms are present in the sterilized article or dosage

form.

Required “Probability”?

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Can we do better than 10-6?

Required “Probability”?

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With heat-labile articles, knowledge of the microbial bioburden present in the article prior to sterilization, based on examination, over a suitable time period, of a substantial number of lots of the presterilized product, is necessary for developing

the sterilization process.

Presterilization Bioburden

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� Bioburden is a potential risk to the patient not only because the sterilization process might not be completely effective, but also post-processing because of the possible presence of residual materials such as allergens, endotoxins, and

exotoxins.

� Monitoring of in-process bioburden of pharmaceutical components and products is an essential element of the overall contamination-control program for

appropriate sterilization process control.

� It may also have adverse impact on product quality and stability. Therefore, although bioburden may be confidently killed by destructive sterilization processes or removed by retentive processes (filtration), its proliferation before

sterilization should be avoided.

Bioburden Monitoring

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� Process controls and cleaning, sanitization, and disinfection programs provide active means for the control of bioburden population and support the sampling, enumeration, and characterization of bioburden necessary to assure that

sterilization processes are effective.

� Destructive sterilization processes, e.g., moist and dry heat sterilization, are developed and validated to kill microorganisms.

� The microorganisms least likely to be retained by a sterilizing filtration process

are those that are potentially smaller than the smallest pores in the filter matrix. Although size exclusion is an important factor, filters do not retain microorganisms solely by sieve retention.


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� Absorption, wherein microorganisms are retained within the filter matrix by entrapment or electrostatic forces, also is an important retention mechanism. The control of prefiltration bioburden is an important risk-mitigation factor in

retentive processes, and this is particularly true when adsorption may be a significant retention mechanism.

� The control of prefiltration bioburden is an important risk-mitigation factor in

retentive processes, and this is particularly true when adsorption may be a significant retention mechanism.


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� Bioburden removal capability therefore depends on the size and number of the bioburden microorganisms, the pore size distribution of the filter, the properties of the solution being filtered, and the filtration process parameters.

� Many products are inherently antimicrobial, and some formulations contain

antimicrobial preservatives, both of which can limit bioburden recovery. Products that are outside of the pH range of approximately 4–9, are strongly hypertonic or

strongly hypotonic, or have low water activity, may reduce the level of recoverable microorganisms.


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� Presterilization bioburden analysis should be conducted on samples that are representative of materials produced during routine preparation and processing.

� Sampling frequency should be established based on previous data, known

variability, batch size, material, process, and environmental influences.

� Bioburden should be recovered and enumerated from samples that are representative of the process material.

� Bioburden evaluation should focus on microorganisms that represent a greater

concern in the sterilization process.

� Total count methods should consider the properties of both the product under evaluation and the characteristics of the process that may affect recovery.

� Cultivation methods, diluents, and media selection must be based on past

experience with the manufacturing process and test material.


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� Bioburden screening for sterilizing filtration processes not yet subjected to formal validation can be performed by passing the material through a 0.45-micron -rated filter and examining the filtrate for viable microorganisms.

� Only those microorganisms that pass the 0.45-micron filter are of interest

because they present the greatest potential challenge to the sterilizing filtration process. They should be evaluated

� Against the upstream bioburden.

� Bioburden of greatest concern includes Pseudomonas, Brevundimonas,

Ralstonia, and Mycoplasma.


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� Microbiological attributes of materials before sterilization and the manufacturing process used for the materials (if applicable)

� Inherent antimicrobial properties of the materials

� Time limits for process execution

� Water activity of the material

� Environmental conditions within the facility

� Equipment design and cleaning

� Sanitization, decontamination, and other active microbial

� Control processes (such as prefiltration, temperature, pH, osmolarity, etc.)

Bioburden Control

The bioburden risk assessment should result in the establishment of critical control points and should include consideration of the following elements:

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� Controlling the bioburden of materials and products to be sterilized will ensure conformance to the levels required by the sterilization process validation.

� Additionally, controlling the bioburden levels of the items to be sterilized assures that residuals (e.g., allergens, endotoxins, and exotoxins) from that population

will also be controlled.

Bioburden Control

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D-Value Concept

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D-value

1 log � Time required to reduce population by 90% or 1 log

� Is only meaningful for the specified lethality conditions

� Moist and dry heat BI D-values have been extensively studied

� D-values for other sterilization methods typically have additional lethality parameters, e.g., RH,

concentration, temperature.

Note: Be careful using published D-values for environmental microorganisms

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The D-value is the time (customarily in minutes) or radiation dose (customarily in kGy) required to reduce the microbial population by 90% or 1 log10 (i.e., to a surviving fraction of 1/10) and must be associated with the specific lethal

conditions at which it was determined. For steam and dry heat, the D-value is a function of temperature. In gas sterilization (ethylene oxide, ClO2, or O3), D-values

are a function of the chemical concentration, relative humidity, and temperature. Similarly, for liquid chemical sterilization the D-value is a function of the temperature and sterilant concentration.

D-Value

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For example, if your product started with 100,000 cfu/g (105 cfu/g) and 1 minute of exposure to sterilizing conditions left 10,000 cfu/g (104 cfu/g), what is the D-Value?

D-Value

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Many sterilization process validations use biological indicators to determine how long an article would need to be exposed to the sterilizing conditions to acquire a sterilization assurance level (SAL) of at least 10-6

Determination of Time for Exposure to Sterilization

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[from <1229.5> Biological Indicators for Sterilization]

� “A biological indicator (BI) is a well-characterized preparation of a specific microorganism that has known resistance to a specific sterilization process.”

What’s a Biological Indicator?

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� What they are

� Uniformly resistant over time

� Non-pathogenic

� Easy to produce, use and test

� Stable over time

� Resistant to treatment

Biological Indicators

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� They are process measurement tools, much like the thermocouple.

� Their destruction in the PQ need NOT be mandatory.

� They should be placed in the load in difficult to penetrate locations.

� They come in many formats: strips, coupons, threads, wire, & suspension.

� Their resistance to the process must be known.

Biological Indicators

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� A minimum PNSU(SAL) of 10-6 is desired for all items.

� That means that in routine operation of the sterilizer, the possibility for a surviving bioburden microorganism must be less than 1 in 1,000,000.

� That has very little to do with the biological indicator resistance, and even less to do with BI population.

What is the Sterilization Objective?

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where:Nu = SAL / PNSUD = D-value of the natural bioburden

F = F-value (lethality / dose) of the processN0 = bioburden population

The lethality is measured in units of time at the D-value condition. This calculation works for all processes where the D-value can be determined.

Calculation of PNSU (SAL)

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Calculation of PNSU (SAL)

The bioburden defines these

The bioindicator and physical measurements

confirm this

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� The execution of sterilization processes can be supported by physical and chemical indicators and integrators that provide an indication that processing is completed. These are available in many different forms for use in conjunction

with many common sterilization processes.

� Sterilization indicators respond to sterilization process parameters in a nonquantitative fashion; i.e., they show passing or failing results. They are useful in an operating environment as a means to identify whether an item has

been exposed to a sterilization process. They are of minimal use in directly establishing process efficacy.

Sterilization Indicators and Integrators

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� Sterilization integrators are more sophisticated devices that react quantitatively in response to one or more of the critical sterilization parameters and yield a result that can be correlated to lethality. The most sophisticated integrators are

radiation dosimeters that are so accurate and robust that their use has displaced the use of biological indicators for the validation of radiation sterilization.

Sterilization Indicators and Integrators

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� An important consideration in any sterilization activity is the selection of an appropriate process from the many possible alternatives: steam, dry heat, gas, radiation, vapor, chemical, or filtration.

� The choice of the appropriate method for a given item requires knowledge of the

sterilization process and information concerning effects of the process on the material being sterilized.

� The selection of a particular sterilizing treatment and the details of its execution

often represent a compromise between the conditions required to destroy or remove the bioburden to the desired level and the impact of the sterilization process on the materials being processed.

� Sterilization processes should be sufficiently robust for certainty of microbial inactivation while avoiding adverse consequences to material quality attributes.

Sterilization Cycle Development

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“A balance must be maintained between the need to assure sterility of the article

and the preservation of its important characteristics as a finished sterile product,

process intermediate or laboratory aid.”

Maintaining a Balance

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� Overkill sterilization is a process where the destruction of a high concentration of a resistant microorganism supports the elimination of bioburden that might be present in routine processing. That objective can be demonstrated by attaining

any of the following: a defined minimum lethality; a defined set of process conditions or confirmation of minimum log reduction of a biological indicator.

� Used wherever possible, consistent with impact on the materials.

Overkill Method

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Overkill Method

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Complete destruction of the BI

Results in an overkill of the bioburden to a PNSU value at the intersection of these lines

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� Bioburden /Biological indicator sterilization is a method in which the incomplete destruction (or destruction of a modest population) of a resistant biological indicator can be used to demonstrate the capability of the process to reliably

destroy any bioburden. This is accomplished using detailed knowledge of the bioburden/biological indicator populations and their relative resistance.

� Used where product quality attributes may be adversely impacted by severe

processing conditions

Bioburden/ BI Method

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Biological IndicatorDeath Curve

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Microbial Death Curves

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Bioburden / BI Method

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Partial BI Destruction

Destruction of bioburden with PNSU indicated at the intersection

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� Bioburden sterilization is a method in which multiple bioburden isolates from the material are evaluated for resistance to the sterilization method and to demonstrate the lethality of the process. Frequent monitoring of the bioburden

population and resistance is mandatory for success.

� Used primarily for radiation sterilization, because of the inadequacy of biological indicators as “worst case” challenges.

Bioburden Method

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Bioburden Method

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Complete bioburden challenge destruction

Destruction of the production bioburden at PNSU here

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� The overkill method employs conditions that are capable of destroying a high concentration of a resistant biological indicator and thus are a greater challenge to material integrity and stability.

� Overkill is employed only where the items being sterilized can withstand

extended exposure to the sterilizing process and is used most commonly for metal, glass, and other items that are unaffected by process exposure.

� Its use is always preferable where materials can tolerate the more aggressive

conditions utilized


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� Bioburden/biological indicator (or combination) methods are appropriate when the product has some sensitivity to the sterilizing conditions.

� Analysts commonly use it for large- and small-volume parenterals, in-process solutions, and laboratory media for which the material properties would be

impaired by a lengthy exposure to the sterilizing conditions.

� The proper use of the method requires control over the presterilizationbioburden levels and confidence that the bioburden's resistance is such that it

will be destroyed during processing.

� The complete destruction of or the use of a high population of the bioburden/biological indicator is not necessary for use of this method because it

relies on differences in the relative resistance and population of the biological indicator and bioburden microorganisms.


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� The bioburden method bases the sterilization duration solely on the expected population and resistance of the bioburden on the materials. This is the method of choice for all radiation sterilization. It relies on periodic bioburden monitoring

and resistance screening to establish confidence in the method. The bioburden method does not require use of a biological indicator.

� Filtration is used for liquids and gases that either will not withstand heat,

radiation, or chemical sterilization processes or are more conveniently sterilized in-line.


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� The spores can be placed in the sterilization load in locations where physical parameter measurements such as temperature or gas concentration cannot be easily obtained (e.g., within needle lumens, syringes, and ampules) or where

measurement may alter the delivered conditions (e.g., sampling of the lethal gas). The biological indicator provides a means to directly assess the sterilizing

effect of the method in a manner not possible by physical measurements. The lethality-based physical measurement and biological inactivation data from a sterilization process should be in reasonable agreement. When this is not the

case, an investigation should be considered.

Biological and Physical Data

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� After a sterilization process has been initially validated, it must be maintained in that state to ensure continued acceptable operation.

� This is accomplished by a number of related activities that are essential for continued use of the method such as Calibration, Physical Measurements,

Physical Integrators/Indicators, Bioburden Sampling, Bioburden resistance determination, biological indicator resistance determination, supplier audits,

Change Control, Preventive Maintenance, Periodic Reassessment and Training.

Routine Process Control

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� Filtration is used for liquids and gases that either will not withstand heat, radiation, or chemical sterilization processes or are more conveniently sterilized in-line.

� What is fundamentally different about this mode of sterilization?

Sterilizing Filtration

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� Microbial retention in sterilizing filters relies on a combination of sieve retention and adsorption. Validation of sterilizing filtration therefore requires determination of the effect of the liquid on the filter, determination of the effect of the filter on

the liquid, and demonstration that the filter can consistently yield sterile solutions under the intended conditions of use.

Sterilizing Filtration of Liquids

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� B. diminuta (ATCC 19146) is used as the challenge organism unless it is not viable in the liquid to be filtered. Viability studies should be used to confirm that the liquid has no adverse effects on the challenge organism. If the challenge

organism is viable in the liquid to be filtered, the liquid should be inoculated to achieve a challenge level of 1 × 107 cfu/cm2, and the filtrate should be evaluated

for the presence of the challenge organism.


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� A method of describing filter-retaining capability is the use of the log reduction value (LRV). For instance, a 0.2-µm filter that can retain 107 microorganisms of a specified strain will have an LRV of not less than 7 under the stated

conditions.


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� If B. diminuta is not viable in the liquid, several options are available, and analysts can (1) modify the liquid to ensure the viability of the challenge organism (e.g., adjust pH or remove the bactericidal component), (2) reduce the

exposure time to ensure that the challenge organism remains viable, or (3) change the challenge organism from B. diminuta to one that has been isolated

from the liquid to be filtered. These studies should employ production process pressure differentials or process flux values as appropriate. If possible, the liquid to be filtered should be used.


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� A sterilizing-grade filter is one that is capable of retaining a minimum 1 × 107 cfuof B. diminuta (ATCC 19146) per square centimeter of effective filter area when tested in accordance with ASTM F838-05 (2013), Standard Test Method for

Determining Bacterial Retention of Membrane Filters Utilized for Liquid Filtration.

� The designation “sterilizing grade” implies a sterilizing action only if other

conditions are met, including the integrity test specification established by the filter manufacturer and validated by the user.

Sterilizing Grade Filters

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� Sterilizing-grade filters typically are microporous membranes that have nominal pore-size ratings of about 0.2 µm. These membranes are fabricated with various materials, have relatively narrow pore-size distributions, and can be integrity

tested. The integrity test results can be correlated with microbial retention.

� Membrane filters that have a nominal pore size of 0.45 µm can be validated to produce sterile filtrates under some conditions; for example, some liquids

require high differential pressures to achieve useful flow rates, and these pressures are not suitable for use with 0.2-µm–rated filters. When manufacturers use 0.45-µm filters, they should ensure particularly stringent

control of presterilization bioburden.

Sterilizing Grade Filters

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� Three different lots of filter membranes should be used for the microbial retention studies.

� The membranes should have pre-use integrity test values that are near the filter manufacturer's specification in order to minimize the possibility that production

filters will fail to meet the integrity test value established during the validation exercise.

� Successful microbial challenge studies result in no microorganisms detectable in

the filtrate.


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� Integrity testing can be used to show that a filter has the correct pore-size rating, is installed properly in its housing, and has not been damaged by the process used to sterilize it .

� These integrity test methods generally rely on detecting gas flow caused by

pressure differential across a wetted membrane

Filter Integrity Testing

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� The bioburden removal capability depends on the available filter retention capacity, which is a function of the inherent bioburden load present in the entire volume of the liquid to be filtered and the effective filter surface area.

� Microbial retention in sterilizing filtration is a function of the upstream bioburden.

Also, nonviable particulate matter that may be present in the solution can influence the retentive capacity of the filter.

� Therefore, the pre-filtration bioburden and particulate levels of the solution

should be minimized and controlled before the final sterilizing filtration step.

Pre-filtration Bioburden Control

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� Various filter configurations and processes can be used to control the bioburden and nonviable particulate levels presented to the final, sterilizing-grade filter. One configuration is a multi-filter arrangement that consists of two sterilizing-

grade filters (or a bioburden reduction filter followed by a sterilizing-grade filter) connected in series.

Pre-filtration Bioburden Control

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USP <1211>:

“While there is general agreement that sterilization of the final filled container as a dosage form or final packaged device is the preferred process for assuring the minimal risk of microbial contamination in a lot, there is a substantial class of

products that are not terminally sterilized but are prepared by a series of aseptic steps.”

Aseptic Processing

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� An aseptic process is designed to prevent the introduction of viable microorganisms into components at any point where no further step would eliminate them.

Aseptic Processing

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� The components of an aseptically processed article may have been sterilized by one of the processes described

� For example, a liquid may have been sterilized by filtration.

� The final empty container components would probably be sterilized by heat, dry heat being employed for glass vials and an autoclave being employed for rubber

closures

Aseptic Processing

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USP <1211>:

“The areas of critical concern are the immediate microbial environment where these presterilized components are exposed during assembly to produce the

finished dosage form and the aseptic filling operation.”

Aseptic Processing

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Critical requirements include:

An air environment free from viable microorganisms, of a proper design to permit effective maintenance of air supply units

The provision of trained operating personnel who are adequately equipped and

gowned.

Aseptic Processing

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� Periodic environmental filter examination

� Routine particulate and microbiological environmental monitoring

� May include periodic sterile culture medium processing

Aseptic Processing

Critical monitoring requirements include:

Aseptic Processing

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Sterile products

present the highest risk to patients

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Manufacture of sterile products must be of the highest control standards

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Customer Product is safe (sterile)

System Validated, repeatable, robust

Approach

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Sterile: complete and unequivocal absence of viable microorganisms

Aseptic: exclusion of viable microorganisms by controlling environment to maintain contamination at levels known to present minimal risk

Aseptic vs. Sterile

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The components of an aseptically processed article may have been sterilized by one of the processes described. For example, a liquid may have been sterilized by filtration

Aseptic Processing

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Aseptic processing involves the separate sterilization of the product and the packaging (container/closures) and the transfer of product into the container, followed by closure, all under microbiologically controlled conditions

Aseptic Processing

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How do we get an aseptic environment?

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Where Do Microbiological Contaminants Come From?

Highest Risk Lower Risk

Human Raw Materials Equipment Environment

module 11 usp 1229 sterilization of compendial articles and usp … · 2021. 1. 18. · sterility...

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