
PDA Technical Glossary
PDA Technical Reports are highly valued membership benefits because they offer expert guidance and opinions on important scientific and regulatory topics and are used as essential references by industry and regulatory authorities around the world. These reports include terms which explain the material and enhance the reader’s understanding.
The database presented here includes the glossary terms from all current technical reports. The database is searchable by keyword, topic, or by technical report. Each definition provided includes a link to the source technical report within the PDA Technical Report Portal.
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- TR 3: Validation: Dry Heat (16)
- TR 48: Moist Heat Sterilizer Systems (15)
- TR 61: Steam in Place (10)
- TR 30: Parametric Release (9)
- TR 51: Biological Indicators (2)
- TR 57: Analytical Method Validation (1)
- TR 58: Temp Controlled Distribution (1)
- TR 70: Cleaning/Disinfection Programs (1)
- TR 74: Reprocessing of Biopharmaceuticals (1)
- TR 13: Environmental Monitoring (1)
- TR 26: Sterilizing Filtration of Liquids (1)
- TR 60-3: Process Validation: A Lifecycle Approach: Bio Drug Sub Mfg (1)
- TR 54-5: Quality Risk Management for the Design, Qualification, and Operation of Manufacturing Systems (1)
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Air Removal Test
A test used to evaluate air removal and steam penetration in an empty sterilizer that is used for porous/hard goods load sterilization (e.g., Bowie-Dick Test, DART, Lantor Cube, Browns’ Test). (TR01) (TR 48)
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Biological Qualification
A component of performance qualification that demonstrates, by use of biological indicators, that the required lethality (FBIO) is achieved consistently throughout the load. (TR1) (TR3) (TR30) A component of performance qualification that demonstrates, by use of biological indicators, that the required lethality (FBIO) or spore log reduction (SLR) is achieved consistently throughout the sterilized or sanitized portion of the SIP system. (TR61)
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Chamber Leak Test
A test conducted to evaluate possible air infiltration to the chamber under vacuum. [Synonym: Vacuum Leak Test] (TR1) (TR48)
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Container Cold Spot
The location within a sealed liquid container that achieves the lowest process lethality (F0) during a sterilization process. (TR01)
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Cool-Down Phase
The phase of a sterilization cycle that occurs after completion of the exposure phase. Parameters of a cool-down phase are typically defined in order to meet applicable user requirements for load cooling and drying. (TR01) The phase of a sterilization cycle that occurs after completion of the exposure phase. [Synonym: post-conditioning phase, slow exhaust phase, drying phase, equalization phase] (TR48) The phase of an SIP cycle that occurs after completion of the exposure phase. Parameters (e.g., time, temperature, pressure) of a cool-down phase are typically defined in order to meet applicable user requirements for system cooling and drying. (TR61)
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DT Value
The time in minutes required for a onelogarithm, or 90%, reduction of the population of microorganisms used as a biological indicator under specified lethal conditions. For steam sterilization, the D-value should always be specified with a reference temperature, DT . For example, a BI system with a D121°C = 1.4 minutes requires 1.4 minutes at 121°C to reduce the population by one logarithm.(TR1) (TR61)
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Dryness Fraction
An absolute measure of the actual latent heat of a sample of steam relative to the theoretical latent heat of saturated steam. (TR01) (TR48)
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Dryness Value
A dimensionless test quantity developed to approximate the dryness fraction. (TR01)
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Equilibration Time
The period that elapses between the attainment of the minimum exposure temperature at the reference measurement point (typically the drain) and the attainment of the sterilization temperature at all points within the load. This period is an indication of the ability to properly remove air and heat the load items; consequently, it is typically only evaluated by placing heat penetration probes in porous/hard goods loads. (TR01) (TR48)
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F-Value (Lethality Factor)
A measurement of sterilization effectiveness, the F-value is the calculated equivalent lethality (using a specified z-value), in terms of minutes at a reference temperature (Tref), delivered by a sterilization cycle. (TR1) (TR3) (TR30) (TR48) (TR61)
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F-Value (Lethality Factor) -- FBiological
A term used to describe the delivered lethality, measured in terms of actual kill of microorganisms on or in a BI challenge system. The FBiological-value is calculated as DT × LR, where DT is the D-value of the BI system at the reference temperature (T) and LR is the actual logarithmic reduction (log N0 – log NF) of the BI population achieved during the cycle. (TR1)
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F-Value (Lethality Factor) -- FO
A term used when the specific reference conditions of Tref = 121.1°C and z = 10°C are used to calculate the equivalent lethality. For example, when the z-value of the BI is 10°C a cycle with an F(T=121.1°C, z=10°C), or F0, equal to 8 minutes is equivalent (in terms of delivered lethality) to a square wave cycle of 8 minutes at 121.1°C. A square wave cycle that provided an exposure of 25.9 minutes at 160deg;C would also yield an F0 of 8 minutes. (TR1)
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F-Value (Lethality Factor) -- Fphysical
A term used to describe the delivered lethality calculated based on the physical parameters of the cycle. The FPhysical-value is the integration of the lethal rate (L) over time. The lethal rate is calculated for a reference temperature (Tref-) and z-value using the equation: L = 10(T-Tref- )/z. (TR1)
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Fraction-Negative Methods
Fraction-negative methods use the starting population of a biological indicator (N0) and data in the quantal range to create a two-point line from which the DT-value can be determined. The quantal range is the exposure period over which a set of replicate test units exhibit a dichotomous response – some are positive for growth and the rest are negative for growth. (TR01)
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Gravity Displacement
A sterilization process based on the principle that cold air within the chamber is heavier than the steam entering and will sink to the bottom of the chamber. As steam enters the chamber, air is pushed out the bottom drain and exits, with the condensate, through a steam trap. (TR01) (TR48) (TR61)
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Half-Cycle Qualification
A qualification method that uses fifty percent of the exposure time to demonstrate sterilization cycle efficacy. The physical and biological lethality values achieved in the half-cycle exposure time are doubled to project the lethality that will be achieved by the full cycle.(TR01)
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Heat-up Phase
The phase of a sterilization cycle that occurs prior to the exposure phase. Process parameters are developed for this phase in order to meet applicable user requirements for load conditioning (e.g., air removal and preheating.) (TR01) (TR3) (TR48) (TR61)
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Liquid Load
A load consisting of closed containers of aqueous liquids. The sterilization of the container contents is achieved through transfer of energy through the container into the aqueous liquid. (TR01) (TR30) (TR48)
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Load Zone
Area within the sterilization chamber where materials to be sterilized may be placed. (TR01) (TR3) (TR48)
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Maximum Load
The maximum quantity or mass of items permitted in a sterilizer load. (TR01) The maximum quantity or mass of items permitted in a depyrogenation or sterilization load. (TR3) The maximum quantity or mass of products permitted in a validated sterilizer load. (TR30)The maximum quantity or mass of items permitted in a sterilizer load. (TR48)
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Minimum Acceptable Cycle (MAC)
The minimum cycle conditions (in terms of delivered minimum lethality or minimum time and temperature) that would be considered acceptable. (TR01) (TR61)
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Mixed Load
A load that contains multiple item item types representing various sterilization challenges. For example, some load items may have air removal challenges, while others pose a challenge due to their mass. (TR01)
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Moist Heat
Steam, steam-air mixtures, and superheated water used for sterilization. (TR01)
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Operating Parameters (Critical Parameters)
Values that are controlled and/or measured and are linked to safety and efficacy of a product or the process. Failure to meet a critical parameter should result in rejection of the load. (TR01) (TR3) (TR48) (TR51)
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Operating Parameters (Key Parameters)
Values that are controlled and/or measured and are used to assure the ongoing “state of control” and consistency of runs. Failure to meet a key process parameter should result in an investigation with a documented rationale for the disposition of the load. (TR01) (TR3) (TR51) (TR48) Values that are controlled and/or measured and are used to assure the ongoing “state of control” of steam in place cycles. Failure to meet a key process parameter should result in an investigation. (TR61)
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Overkill Design Approach
A sterilization design approach where minimal information is required about the product bioburden. A worst-case bioburden assumption is used to determine the delivered lethality needed to achieve a PNSU of 10-6 on or in the items being sterilized. When using this approach, the qualification program must demonstrate that both the FBIO and FPHYS are greater than 12 minutes. The required lethality may vary regionally. (Note: For typical SIP systems, the FPHYS will need to be greater than the FBIO.) (TR01) (TR3) (TR30) (TR61)
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Parametric Release
A sterility release system based upon effective control, monitoring, documentation, and batch records review of a validated sterilization process cycle in lieu of release procedures based upon end-product sterility testing. (TR01) (TR3) (TR13) A sterility release program based on effective control, monitoring and documentation of a validated sterile-product manufacturing process where sterility release is based on demonstrated achievement of critical operational parameters and performance attributes in lieu of end-product sterility testing. (TR30)
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Penetration Probe
A probe placed in contact with the load item or inside a container of liquid to measure the temperature of the load item or liquid. (TR01) A thermocouple placed in contact with the load item to measure the temperature of the load item. (TR3)
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Physical Qualification
A component of performance qualification that demonstrates that predetermined physical requirements, including temperature distribution and heat penetration, are achieved consistently throughout the load. (TR01)(TR03)
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Probability of a Non-Sterile Unit (PNSU)
The number that expresses the probability of occurrence of a non-sterile unit after exposure to a sterilization process. Within the pharmaceutical industry, a design end point better than or equal to the probability of one non-sterile unit in a million units is expected, i.e., PNSU ≤ 10–6. [Synonym: Steriliy Assurance Level (SAL)] (TR01)
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Process Performance Qualification
Documented verification that a system is capable of consistently performing or controlling the activities of the processes it is required to perform or control, according to written and preapproved specifications, while operating in its specified operating environment. (TR01)
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Product-specific Design Approach
A sterilization design approach that is based on the characteristics of the bioburden (on or in the load) and the heat sensitivity of the product that delivers the lethality needed to achieve a PNSU of 10-6 on or in the items to be sterilized. (TR01) (TR3) (TR30)
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Sterilization Cycle
A sequence of defined operating parameters (e.g., time, temperature and pressure) and conditions required to render an item sterile. (TR01) (TR30) (TR48) A sequence of defined operating parameters (e.g., time and temperature) required to render an item sterile. (TR3)
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Sterilization Run
Execution of a sterilization cycle. (TR01)
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System Suitability Evaluations
Physical evaluations (e.g., chamber integrity or air removal) conducted on a scheduled frequency to demonstrate ongoing control of the sterilizer system. (TR01)
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Temperature Distribution
Temperature measurement of the heating medium (e.g., forced hot air) across the chamber load zone. (TR01) (TR03) (TR30) (TR48)
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Validation
A documented program that provides a high level of scientific assurance that a manufacturing process will reliably produce acceptable product. The proof of validation is obtained through rational experimental design and the evaluation of data, preferably beginning from the process development phase and continuing through the commercial production phase. (TR01)
A documented program that provides a high degree of assurance that a specific process, method, or system will consistently produce a result meeting predetermined acceptance criteria. (TR26) (TR57) (TR70) (TR74)
Documented testing, performed under highly controlled conditions, which demonstrates that a process consistently produces a result that meets predetermined acceptance a result that meets predetermined acceptance criteria. Used to test processes, methods, and systems for which conditions can be controlled in the real world (i.e., after completion of testing, when the process is in use). Transportation processes can be qualified but not validated; in the real world, it is not possible to exert control over all parameters that could affect the transportation process (e.g., weather, customs, traffic delays, mechanical failures, etc.). (TR58)
A documented program that provides a high degree of assurance that a specific process, method, or system will consistently produce a result meeting predetermined acceptance criteria. (Note: Validation is a lifecycle program which may include development and qualification activities for one or more elements/systems that form a process.) (TR54-5)
A documented program that provides a high degree of assurance that a specific process, method, or system will consistently produce a result meeting pre-determined acceptance criteria (17). (TR60-3)
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Worst Case Load
The load configuration that is determined to be most difficult to sterilize. This is a function of the cycle control strategy and load item characteristics (e.g., mass, configuration, or air removal challenges). For porous/hard goods loads, this may not necessarily be the minimum or maximum load. (TR01) The load configuration that is determined to be most difficult to sterilize or depyrogenate. This is a function of the process control strategy and load item characteristics (e.g., mass, configuration). (TR3)
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Z-Value
The number of degrees of temperature change necessary to change the D-value by a factor of 10. The z-value allows integration of the lethal effects of heat as the temperature changes during the heating and cooling phases of a sterilization cycle. (TR01) (TR3) The number of degrees of temperature change necessary to change the D-value by a factor of 10. The z-value allows integration of the lethal effects of heat over time (i.e., calculation of F0) as the temperature changes in a cycle. (TR61)