inprocess 1211

In-Process Changes to USP <1211> Sterilization & Sterility Assurance of Compendial Articles

James AgallocoAgalloco & Associates

DisclaimerThis presentation draws on in-process drafts currently in preparation within USP’s Microbiology Expert Committee.The interpretations and emphasis placed on subjects within this presentation are the author’s personal opinion and not official USP positions.The draft chapters that are issued by USP in Pharmacopeial Forum on these subjects differ somewhat from this presentation.

Who’s on the Micro Expert Committee?

James Akers, Ph.D., AK&A, ChairmanJames Agalloco, A&ADilip Ashtekar, Ph.D., Gilead SciencesAnthony Cundell, Ph.D., Merck & Co.Dennis Guilfoyle, Ph.D., FDA ORA liaisonRajesh Gupta, Ph.D., FDA CBER liaisonDavid Hussong, Ph.D., FDA CDER liaisonKaren McCullough, RMSRussell Madsen, TWGRanda Melhem, Ph.D. CBER liaisonJianghong Meng, Ph.D., University of Maryland,Leonard Mestrandrea, Ph.D., Mestrandrea LLCRainer Newman, Johnson & Johnson (retired)Mickey Parish, Ph.D., FDA CFSAN liaisonDonald Singer, GlaxoSmithKlineScott Sutton, Ph.D., Microbiology NetworkEdward Tidswell, Ph.D., BaxterRadha Tirumalai, Ph.D, USP Staff liaison

What’s Wrong?Despite the maturity of the subject, the practice of sterilization within the global healthcare industry has descended into rote repetition of wrong headed expectations.Regulatory obfuscation and industry apathy have caused all manner of unnecessary complications and added patient risks.Rather than making products safer, we may have actually increased patient risk!

Why did it go Wrong?We’ve largely ignored the core science that underlies all sterilization processes.We have relied on rote repetition of activities using overly simplistic models and ignored the core scientific principles upon which sterilization process must be constructed.If we haven’t made it sterilization any easier, we’ve sure made it dumber.

What are the Problems? - 1Failures to adequately sterilize.Aseptic processing where terminal sterilization could be used.Shortened expiration dates for products.Increased impurities, particles, extractables.Wasted energy costs and lost capacity due to over-processing.

What are the Problems? - 2Ignorance of the objectives.Oversimplification of key concepts.Inadequate training of industry.Confusion among disciplines.Excess caution built into protocols.Regulatory excess.Industry is risk averse to an extreme.Industry would rather switch than fight!

Sterilization Microbiology 101:

What you absolutely must know in only 5 slides!

What’s the Primary Objective?

A minimum PNSU of 10-6 is required.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.It has little to do with the biological indicator, and even less to do with the BI population.

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Biological IndicatorDeath Curve

BioburdenDeath Curve

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Microbial Death Curves

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Not Here

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D - Value

The D-ValueThe D-value is the time required to reduce a population of microorganisms by one log or a 90% reduction in count.A D-value is only meaningful if referenced to specified lethal conditions.For example D-values should always be referenced to a temperature, without that reference they have no meaning, i.e., moist heat D121.1°C or dry heat D170°C. For D-values in gases / liquids the agent concentration, RH and temperature must be indicated, i.e., D900 PPM, 75% RH,30°C

where: 

Nu = SAL / PNSU

D = D-value of the natural bioburdenF = F-value (lethality) of the processN0 = bioburden population

Calculation of PNSU (SAL)

What’s Been Missing?

Impact of Sterilization

A balance must be achieved between the need to maintain a safe, stable and efficacious product while providing sufficient lethality to attain a minimum level of sterility assurance.

The Forgotten ObjectiveAchieving sterility (aka minimum PNSU) is only half of what must be accomplished.In order to use the materials after the process their essential quality attributes have to be maintained.We can most definitely have too much of a good thing. If in the effort to kill microorganisms, we do lasting physical or chemical damage to the items being sterilized we have accomplished nothing of value.

Consequences of Over-processing

Reduce potencyIncreased degradation Increase in extractables / leachablesIncrease in particles – visible & sub-visibleLoss / weakening of package integrityAppearance changesChanges in physical propertiesLimited growth promotion (lab media)And most important of all – using an aseptic process instead of a terminal sterilization process.

What is USP’s Role?

USP’s General ChaptersUSP intends that General Chapters above 1000 will be entirely informational and will not contain monograph-related requirements. Topics that might be covered in informational chapters include: Background, theory, and future directions/applications Areas that need standards, e.g., nanotechnology Safety approaches and information Guidance chapters for good food and drug practices Drug development and registration documents Supply chain management documents, including GMP

analyses and comparisons Comparisons across the USP compendia.

General Chapter Management in the 2010–2015 Cycle, PF, Vol. 35, 5, Sept-Oct 2009

USP <1211> & Related Content

The core of this chapter dates to the 1980’s and the supportive elements were developed to address specific needs.The combined set of chapters is a patchwork quilt of somewhat disconnected ideas.Additionally, technological advances have made some of the content out of date.We did a quick fix in 2010 to fix the biggest problems and outlined a plan for a complete revision of all sterilization & sterility assurance related content.

<1211> The Planned Revision

Started Here: Sterilization at a more basic level: more instruction, less standardization

Individual chapters on each sterilization method: allows for easier revision.

Separate gas & vapor sterilization; Separate dry heat sterilization & depyrogenation; separate steam for parts and liquid filled containers; none of these are really the same process

New chapters on chemical sterilization: no prior information Aseptic processing as a separate chapter: not strictly a

sterilization subject; needs better connection to other supportive chapters

Update references throughout. New definitions for sterilization validation models. Clarify the role of the biological indicator. Clarify PNSU, SAL and risk to patient.

Integrate Endotoxin Indicator chapter as well as BI & CI content. Move BI monographs out of “official chapters”. Allow for easier development of other needed content in future. Depyrogenation treated independently of sterilization

Finished Here: Separation of Sterilization, Depyrogenation and Sterility Assurance content.

The Game PlanRevise the entire content, separating it for ease of development, review, approval and roll out.The current content will remain in place and be revised in piece meal fashion.Sterilization process specific content has been given priority, but supportive content revision is also underway.The first draft of chapters will appear in Pharmacopeial Forum beginning in 2012.

Old & New Structure Overview

<1211>Sterilization & Sterility Assurance of Compendial Articles will be divided into three major areas: <1211> General Concepts for Sterility Assurance

Aseptic Processing, Environmental Monitoring, Sterility Testing, Parametric Release, & other general sterility assurance related content

<1229> General Concepts for Sterilization Sterilization processes, BI, CI’s, other sterilization related

content <1228> General Concepts for Depyrogenation

Depyrogenation processes, EI’s, other related content

Work on <1211> section has been deferred because it is believed that sterilization & depyrogenation chapter revisions are more urgently needed.

What’s been completed so far

Where are we now?The planned structure is largely defined.We are working on multiple tracks Sterilization Process chapters – with most

used first Steam for Parts / Hard Goods Steam for Liquid Filled Containers Sterilizing Filtration Radiation Sterilization Gas Sterilization

Sterilization Support chapters beginning with Bioburden Monitoring Biological Indicators (starting soon)

Depyrogenation processes – starting soon & independent of the sterilization effort

<1229> Introductory Chapter

Provides an overview and introduces common elements related to all sterilization methods. Includes: Establishing & Justifying Sterilization

Processes D-value and Microbial Resistance Biological & Physical Data Sterilization Indicators & Integrators Selection of an Appropriate Method Routine Process Management

<1229> The Main Point“It is generally accepted that sterilized articles or devices purporting to be sterile attain a 10–6 microbial survivor probability, i.e., assurance of less than 1 chance in 1 million that viable bioburden microorganisms are present in the sterilized article or dosage form.”

Overkill Sterilization

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Complete destruction of the

Biological Indicatorat this time point

Results in Overkill of the bioburden to the PNSU

where these line intersect

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BB/BI with 106 BI Challenge

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Partial destruction of the BI at this point

Destruction of the Bioburden where these lines intersect

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PNSU

BB/BI with <106 BI Challenge

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Complete destruction of the BI at this point

Destruction of the Bioburden where these lines intersect

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PNSU

Bioburden Method

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Complete destruction of the bioburden challenge

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Destruction of the lot bioburden

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Steam Sterilization

<1229S> Direct Steam Sterilization

Separated prior sub-chapter into parts <1229S> and liquids <1229A> to allow for differences, and greater clarity. “overkill approach” is the method of choice.Separates processes where over-processing is not a concern from those where it is.In theory parts sterilization has no upper limit, while terminal / liquid sterilization is bounded both above and below the desired process.

Parts vs. Liquid Sterilization

Non-Sterile

Sterile

SterileStable

SterileNon-Stable

Product Quality Attributes Product Quality Attributes Non-issue - Overkill MethodNon-issue - Overkill Method

Non-SterileStable

Heat Input

Product Quality Attributes Product Quality Attributes An issue – BB/BI MethodAn issue – BB/BI Method

1229A1229S

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<1229A> Steam Sterilization of Aqueous Liquids

The method of choice for liquid parenteral products, and similar processes are utilized for laboratory media and process intermediates.“Where the overkill approach can be utilized for terminal sterilization of sealed liquid containers, it is the preferred approach.”“a dual set of requirements is established for nearly every important processing parameter. Sterilization time-temperature or F0 conditions will include both lower (sterility related) and upper (stability related) limits to simultaneously assure safety and efficacy of the processed materials.”

<1229A> Steam Sterilization of Aqueous Liquids

Terminal sterilization of products High/Low F0, variety of BI’s, Overkill & BB/BI

methodMedia for laboratory usage High/Low F0, Overkill & BB/BI method, BI

usage? - self indicating?Intermediates / process aidesHigh/Low F0, BI usage, Overkill & BB/BI method

Laboratory and production bio-wasteLow F0, G. stearothermophilus, Overkill method, condensate collection / kill

<1229A> Steam Sterilization of Aqueous Liquids

Probability of a Non-Sterile Unit (PNSU)

WhereNu = Probability of a Non-Sterile Unit

D = D-value of the natural bioburdenF = F-value of the processN0 = bioburden population per container

Validation Routine Usage

F0 = 8.0 minutes F0 = 8.0 minutes

D121 of BI = 0.5 minutes D121 of bioburden = 0.005 minutes

N0 of BI = 106 N0 of bioburden = 100 ( or 102)

PNSU for BI = 10-10 PNSU for Bioburden = 10-1,598

Sterilization by Filtration

Sterilization by Filtration Draft

Sterilizing filtration is a retentive process, not a destructive one.Physical removal of microorganisms depends on the upstream bioburden, the properties of the solution, the filtration conditions and the filter itself.Can be validated to consistently yield solutions that are sterile as defined in <1229>.

Sterilization by Filtration - 1Definition and description of “sterilizing-grade filter”Retention mechanisms and factors affecting retention Nature of “pores” and microorganisms Composition and structure of filter matrix Composition of filtered solution Filtration conditionsFilter efficacy Log-reduction value

Sterilization by Filtration - 2ValidationIntegrity test principles and methods Bubble point Diffusive flow Pressure holdPre- and post-filtration and sterilization integrity testingThe need for pre-filtration bioburden controlTroubleshooting common filtration problems

Radiation Sterilization

<1229R> Radiation Sterilization

“The prevalent radiation usage is either gamma rays or electron beams. Other methods utilize x-rays, microwaves and visible light. The impact of radiation on materials can be substantial and is a major consideration in the selection of radiation as a processing method.”“Radiation sterilization is unique in that the basis of control … is the absorbed radiation dose, which can be precisely measured. Dose setting and dose substantiation procedures are used to validate the radiation dose required to achieve sterility assurance level.”

<1229R> Radiation Sterilization

The use of BI’s in radiation sterilization is not necessary: Non-spore-formers have been identified as

more resistant than B. pumilus. Dose measurement is accurate and has been

closely correlated to microbial destruction.The dose setting methods of AAMI/ISO are well established and easily adapted to pharmaceutical applications. VDmax has been utilized for terminal sterilization of several pharmaceutical preparations.

VDMAX – Example 1

VDMAX – Example 2

Gas, Liquid & Vapor SterilizationSimilar but not the same

Gas, Liquid & Vapors - D-Values

A D-value is only meaningful if referenced to specified lethal conditions. For example wet or dry heat D-values should always be referenced to a temperature, without that reference they have no meaning, i.e., D121.1°C or D170°C.

For D-values in gases / liquids the agent concentration, RH and temperature must be indicated, i.e., D900 PPM, 75% RH, 30°C

D-values cannot be accurately determined for vapors.

<1229G> Gas SterilizationApplicable to single phase gaseous processes only. Condensation of the agent is not a

consideration in the execution of these processes.

Ethylene oxide – model for all systems Chlorine dioxide OzoneTwo validation approaches defined Traditional half-cycle method Bracketing method – variations in

concentration, relative humidity and temperature. More efficient & more scientific as well.

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Half CycleKill of

Bioburden

Half CycleKill of

Bioindicator

Full Cycle

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Half Cycle ApproachDeath Curves

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Validation Cycles

RoutineProcess

<1229L> Liquid SterilizationChemical Sterilants in aqueous solutions Aldehydes – CH2O, CH3CHO, etc. Acids – HNO3, H2SO4, peracetic, etc. Bases – NaOH, KOH, etc. Oxygenating compounds – H2O2, O3, ClO2, etc. Halides – NaOCl, Cl2, etc.

Must include an aseptic post-cycle quench step to stop process prior to adverse material impact.Validation like gas sterilization. The phase is different but the same parameters apply.

Gas/Liquid vs. Vapor Sterilization

Gases are more penetrating, liquids more uniform in concentration, and both are less subject to variations in temperature and relative humidity.Vapors will have different concentrations in each phase. When a vapor has 2 possible condensable components it is even more difficult to predict conditions anywhere.

<1229V> Vapor SterilizationIntended for condensing vapor systems (gas and liquid phases present simultaneously) Hydrogen Peroxide Peracetic Acid

The presence of multiple phases simultaneously complicates concentration determination at the point of sterilization.D-value determination is problematic because of difficulties with parameter measurement in a multi-component 2 phase system.Approaches for validation are a hybrid of the liquid and gas sterilization methods.

<1229V> Vapor SterilizationThe kill rates in the gas and liquid phase are different reflecting the different concentrations and moisture present in each phase.The conditions within a vapor system are unlikely to be constant & uniform because the agent supply is at a higher temperature than the chamber.The conditions at any location may change during the course of the process.Reproducible kill is possible despite all of the complication because the agent is lethal in both phases; It’s more complex than any of the other methods.

<1229V> Vapor SterilizationTwo validation approaches can be utilized, with the only supportive evidence derived from microbial destruction. Traditional half-cycle method Bracketing method

The linearity of microbial destruction cannot be assured as the process conditions may not be completely homogeneous.The efficacy of the agents used should assure sterilization, however we do not have the ability to predict the outcome because the process parameters may vary substantially across the chamber.

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Bi-Phasic Kill Possibilities

Gas PhaseThroughout

Liquid PhaseThroughout

Gas Phase EarlyLiquid Phase Late

Liquid Phase EarlyGas Phase Late

The difference in kill rates Is unknown

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Bi-Phasic Death Curves

Gas Phase Death Curve

Liquid Phase Death Curve

Composite Death Curve

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Validation Cycles

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Dry Heat Sterilization

<1229H> Dry Heat Sterilization

Distinction has been made between dry heat sterilization and depyrogenation because of major process differences. Dry heat sterilization: Is almost always performed in ovens in a batch

process. Uses a biological indicator B. atrophaeus. Is usually in the 160-180°C temperature range. A reasonable mathematical correlation between

physical data and microbial effect exists.Physical requirements are less definitive than for steam processes, but still apply.Dry heat depyrogenation will be in a separate chapter.

<1229> Bioburden Monitoring

Reviews the relevant concerns for bioburden content Ability to survive the process Population Risk to Public HealthConsiders patient & product impact Provides a decision tree for use in establishment of a monitoring program.

Depyrogenation

<1228> Depyrogenation Methods

<1228D> – Dry Heat Depyrogenation<1228C> – Chemical Depyrogenation<1228F> – Depyrogenation by Filtration<1228P> – Depyrogenation by Physical Means

All of these need integration with endotoxin indicator and testing chapters.

<1228D> Dry Heat Depyrogenation

Differs from dry heat sterilization in several ways:Dry heat depyrogenation: Predominantly utilized for glass and stainless

steel items. Batch and continuous processes are in use. An endotoxin monograph has been completed

and will be inserted within the overall <1228> revision.

Usually in the >200-300°C temperature range. Mathematical correlation between physical data

and microbial effect is extremely poor. Defined physical parameters have proven problematic.

Endotoxin destruction is the primary goal.

<1229?> Biological Indicators

Major changes are anticipated for USP’s existing biological indicator content.Bring together in one comprehensive chapter the content currently found in: <1211> Sterilization & Sterility Assurance of

Compendial Items <1035> Biological Indicators for Sterilization <55> Biological Indicators —Resistance

Performance Tests

And

<1229?> BI Monographs Biological Indicator for Dry-Heat Sterilization,

Paper Carrier Biological Indicator for Ethylene Oxide

Sterilization, Paper Carrier Biological Indicator for Steam Sterilization,

Paper Carrier Biological Indicator for Steam Sterilization, Self-

Contained Biological Indicators for Moist Heat, Dry Heat,

and Gaseous Modes of Sterilization, Liquid Spore Suspensions

Biological Indicators for Moist Heat, Dry Heat, and Gaseous Modes of Sterilization, Nonpaper Carriers

The Rest of the Story

Old & New Structure Overview

<1211> Existing Sterilization & Sterility Assurance of Compendial Articles will be divided into three major areas: <1211> General Concepts for Sterility

Assurance Aseptic Processing, Environmental Monitoring,

Sterility Testing, Parametric Release, & other general sterility assurance related content

<1229> General Concepts for Sterilization Sterilization processes, BI, CI’s, other sterilization

related content <1228> General Concepts for Depyrogenation

Depyrogenation processes, EI’s, other related content

<1211> Introductory ChapterGeneral Concepts for Sterility AssuranceAddress the relationship between sterility, and sterilization, tying in sterilization, aseptic processing, environmental monitoring and sterility testing to provide greater clarity.

Sterilization process controls -> sterility (terminally sterilized products)

Sterilization process controls (multiple processes) -> aseptic processing / environmental monitoring -> sterility (aseptically produced products)

Planned New Chapters in 1211?

Revised content on aseptic processing (currently in 1211, but minimally detailed). Needs linkage to revised <1116> Microbiological Control and Monitoring of Aseptic Processing Environments.New content necessary on the use of RABS & isolators for aseptic processing.

<1222> Parametric Release of TS

Aligns the guidance with global regulatory expectations.Must be aligned with <1229>,<1229T>, <1229G>,<1211H> and <1229R> as these chapters evolve because all of these sterilization chapters are relevant for parametric release.

Planned New Chapters in 1211?

1211T – Terminal sterilization perspectives covering all process types (combination with 1222 is possible).1211P – Post Aseptic Fill adjunct treatment using either radiation or moist heat.Integrate <1207> Container-closure integrity with possible new content in <1211> and <1229>. Microbiology Expert Committee members are involved with the <1207> revision.

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