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 1: Validation: Moist Heat (5)
- TR 3: Validation: Dry Heat (2)
- TR 33: Rapid Micro Methods (2)
- TR 47: Virus Spikes/Virus Clearance (1)
- TR 48: Moist Heat Sterilizer Systems (1)
- TR 50: Alt. Methods Mycoplasma Testing (1)
- TR 53: Stability Testing New Drug Products (1)
- TR 61: Steam in Place (1)
- TR 62: Manual Aseptic Processes (1)
- TR 67: Objectionable Microorganisms (1)
- TR 70: Cleaning/Disinfection Programs (1)
- TR 13: Environmental Monitoring (1)
- TR 29: Validation: Cleaning (1)
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- TR 45: Depth Filtration (1)
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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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F-Value (Lethality Factor)-- FH
A term used when the specific reference conditions of Tref = 160°C and z=20°C are used to calculate the equivalent lethality. For example, when the z-value of the BI is 20°C a process with an F(T=160°C, z=20°C), or FH, equal to 8 minutes is equivalent (in terms of delivered lethality) to a square wave process of 8 minutes at 160°C. A square wave process that provided an exposure of 45.2 minutes at 145°C would also yield an FH of 8 minutes. (TR3)
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False Negative
A test result that is erroneously classified in a negative category (e.g., the absence of a viable microbial detection result when viable microorganisms are present). (TR33)
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False Positive
A test result that is erroneously classified in a positive category (e.g., a viable microbial detection result when viable microorganisms are not present). (TR33)
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Fastidious strain (isolate)
A population of microorganisms having complex nutritional requirements and thus difficult to cultivate. (TR50)
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Fermentation Broth
The fluid and all constituents in a fermentation vessel prior to separation. (TR45)
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Finished Materials
This term refers to items such as drug substances, drug products, finished product held in bulk before final packaging, and clinical trial materials that are likely to be stored for significant periods of time and are also subject to the risks of distribution. (TR53)
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First Air
Refers to the air exiting at the face of HEPA filters. Based on the airflow through HEPA filters and its unidirectional air flow the air exiting at the filter face is for the purposed of aseptic processing free of particulate contamination (both viable and non-viable). (TR70)
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First Air (First Work Location)
The work location first in the path of HEPA filtered air. (TR62)
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Focus Forming Unit (FFU)
A measure of virus infectively based on formation of a region or “focus”, of infected cells within a monolayer culture that is caused by viruses that do not kill their host, but rather transform them. The number of foci is directly correlated to the number of infectious virus particles. (TR47)
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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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Frank (Canonical) Pathogens
Microorganisms responsible for infection in healthy individuals (i.e., individuals with normal operative and functional host defense mechanisms) that may be acquired from exposure to other infected people or animals, environmental reservoirs (exogenous) or the individual’s normal (endogenous) microbial flora. (TR67)
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Free Drained Equipment
No visible water pool in the equipment or line when viewed under appropriate lighting conditions (but may contain water droplets). (TR29)
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Frequent Monitoring
A process of collecting data in which conditions are monitored at a defined frequency not exceeding sixty minutes during operation. In most U.S. applications, this means “during production.” (TR13)