Parts sterilization places no limit on the heat input to the materials (usually glass, stainless steel, and other heat stabile materials). There is a requirement for minimum heat and nothing more. These types of processes are ordinarily validated using an overkill approach. Terminal sterilization places both a lower and upper limit on the amount of heat required. The process must fit a window between the minimum time-temperature to make the materials sterile, and a maximum time-temperature where product quality attributes are disrupted by the treatment. Terminal sterilization can be validated using either the overkill (less common) or bioburden /biological indicator (BB/BI) approach.
Many Thanks for Your Attention
In-Process Changes to USP<1211> Sterilization & SterilityAssurance of CompendialArticles James Agalloco Agalloco & Associates
Disclaimer This 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, Chairman James Agalloco, A&A Dilip Ashtekar, Ph.D., Gilead Sciences Anthony Cundell, Ph.D., Merck & Co. Dennis Guilfoyle, Ph.D., FDA ORA liaison Rajesh Gupta, Ph.D., FDA CBER liaison David Hussong, Ph.D., FDA CDER liaison Karen McCullough, RMS Russell Madsen, TWG Randa Melhem, Ph.D. CBER liaison Jianghong Meng, Ph.D., University of Maryland, Leonard Mestrandrea, Ph.D., Mestrandrea LLC Rainer Newman, Johnson & Johnson (retired) Mickey Parish, Ph.D., FDA CFSAN liaison Donald Singer, GlaxoSmithKline Scott Sutton, Ph.D., Microbiology Network Edward Tidswell, Ph.D., Baxter Radha 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? - 1 Failures 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? - 2 Ignorance 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 Microbiology101: 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.
106 Microbial Death 103 Curves 100 Biological Indicator Death Curve 10-3 Here 10-6 Not Here 10-9n ot a u po P 10-12 i l 10-15 Bioburden Death Curve 10-18 3 6 9 12 15 18 21 24 27 30 Time
106 D - Value 105 Biological 10 1 log 4 Indicator 103 Death Curve 102 101not a upo P 100 D value i l 10-1 10-2 3 6 9 12 15 18 21 24 27 30 Time
The D-Value The 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
Calculation of PNSU (SAL) −Flog N u = + log N 0 Dwhere: Nu = SAL / PNSU D = D-value of the natural bioburden F = F-value (lethality) of the process N0 = bioburden population
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 Objective Achieving 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 potency Increased degradation Increase in extractables / leachables Increase in particles – visible & sub-visible Loss / weakening of package integrity Appearance changes Changes in physical properties Limited growth promotion (lab media) And most important of all – using an aseptic process instead of a terminal sterilization process.
USP’s General Chapters USP 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 Plan Revise 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.
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 106 103 Complete destruction of the 100 Biological Indicator 10-3 at this time point 10-6 10-9 P n u p o a t i l Results in Overkill of the 10-12 bioburden to the PNSU 10-15 where these line intersect 10-18 3 6 9 12 15 18 21 24 27 30 Time
BB/BI with 10 BI Challenge 6 106 103 Partial destruction of the BI at this point 100 10-3 10-6 Destruction of the Bioburden where these lines intersect 10-9 P n u p o a t i l 10-12 PNSU 10-15 10-18 3 6 9 12 15 18 21 24 27 30 Time
BB/BI with <10 BI Challenge 6 106 103 Complete destruction of the BI at this point 100 10-3 10-6 Destruction of the Bioburden where these lines intersect 10-9 P n u p o a t i l 10-12 PNSU 10-15 10-18 3 6 9 12 15 18 21 24 27 30 Time
Bioburden Method 106 103 Complete destruction of the bioburden challenge 100 at this point 10-3 10-6 10-9 Destruction of the lot P n u p o a t i l PNSU bioburden 10-12 where these lines intersect 10-15 10-18 3 6 9 12 15 18 21 24 27 30 Time
<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 Heat Input 1229A1229S Sterile Non-Stable Sterile Sterile Stable Non-Sterile Non-Sterile t ae Ht c ei D Stable r t c ei dn r IProduct Quality Attributes Product Quality AttributesNon-issue - Overkill Method An issue – BB/BI Method
<1229A> Steam Sterilization ofAqueous 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 ofAqueous Liquids Terminal sterilization of products High/Low F0, variety of BI’s, Overkill & BB/BI method Media for laboratory usage High/Low F0, Overkill & BB/BI method, BI usage? - self indicating? Intermediates / process aides High/Low F0, BI usage, Overkill & BB/BI method Laboratory and production bio-waste Low F0, G. stearothermophilus, Overkill method, condensate collection / kill
<1229A> Steam Sterilization ofAqueous Liquids Probability of a Non-Sterile Unit (PNSU) −F log N u = + log N 0 Where D Nu = Probability of a Non-Sterile Unit D = D-value of the natural bioburden F = F-value of the process N0 = bioburden population per container Validation Routine Usage F0 = 8.0 minutes F0 = 8.0 minutesD121 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 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 - 1 Definition 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 conditions Filter efficacy Log-reduction value
Sterilization by Filtration - 2 Validation Integrity test principles and methods Bubble point Diffusive flow Pressure hold Pre- and post-filtration and sterilization integrity testing The need for pre-filtration bioburden control Troubleshooting common filtration problems
<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.
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 Sterilization Applicable 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 Ozone Two validation approaches defined Traditional half-cycle method Bracketing method – variations in concentration, relative humidity and temperature. More efficient & more scientific as well.
106 Half Cycle Approach 103 Death Curves 100 Half Cycle Kill of 10-3 Bioindicator 10-6 Half Cycle 10-9not a upo P 10-12 i l 10-15 Full Cycle Half Cycle 10-18 Kill of Bioburden 3 6 9 12 15 18 21 24 27 30 Time
106 103 Bracketing Approach 100 Death Curves “w 10-3 or st ca se X Validation Cycles ”m 10-6 at eria 10-9 X l scnot a upo P yc “w le or ro st ut 10-12 ca in se e st ” i l st er 10-15 er ili Routine il za iz X at tio io Process n n 10-18 cy cy cl cl e e 3 6 9 12 15 18 21 24 27 30 Time
<1229L> Liquid Sterilization Chemical 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 Sterilization Intended 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 Sterilization The 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 Sterilization Two 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.
106 Bi-Phasic Kill Possibilities 103 100 Gas Phase Throughout 10-3 Gas Phase Early Liquid Phase Late 10-6 The difference 10-9 Liquid Phase Earlynot a upo P in kill rates Is Gas Phase Late 10-12 unknown i l 10-15 10-18 Liquid Phase Throughout 3 6 9 12 15 18 21 24 27 30 Time
106 103 Bi-Phasic Death Curves 100 10-3 Gas Phase Death Curve 10-6 10-9not a upo P “w or st Liquid Phase Death Curve 10-12 ca Composite Death Curve se i l ” 10-15 ma te r ial 10-18 s cy cle 3 6 9 12 15 18 21 24 27 30 Time
106 103 Vapor Process Bracketing Approach 100 Death Curves “w ors 10-3 tcas X Validation Cycles e” 10-6 ma ter X i a ls 10-9not a upo P cyc “w “w or or ro r le st st uou 10 ca tint -12 se ca ene i ” se st s i l st erte er ” 10-15 ili iliri ma Routine z zaiz X at l te r io tiat ono Process n ial cy i 10-18 cyc n cl sc e clyc yc e le le 3 6 9 12 15 18 21 24 27 30 Time
<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 Health Considers patient & product impact Provides a decision tree for use in establishment of a monitoring program.
<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
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 Chapter General Concepts for Sterility Assurance Address 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 ofTS 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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