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 70: Cleaning/Disinfection Programs (5)
- TR 51: Biological Indicators (3)
- TR 1: Validation: Moist Heat (3)
- TR 3: Validation: Dry Heat (3)
- TR 48: Moist Heat Sterilizer Systems (2)
- TR 61: Steam in Place (2)
- TR 69: Bioburden/Biofilm Management (2)
- TR 13: Environmental Monitoring (2)
- TR 45: Depth Filtration (2)
- TR 49: Validation: Cleaning Biotech (1)
- TR 57: Analytical Method Validation (1)
- TR 26: Sterilizing Filtration of Liquids (1)
- TR 29: Validation: Cleaning (1)
- TR 77: The Manufacture of Sterile Pharmaceutical Products Using Blow-Fill-Seal Technology (1)
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D-Value
The time in minutes required for a one-logarithm, or 90%, reduction of the population of microorganisms used as a biological indicator under specified lethal conditions. For dry-heat sterilization, the D-value should always be specified with a reference temperature, DT. For example, a biological indicator (BI) challenge system with a D 160°C=1.9 minutes, requires 1.9 minutes at 160°C to reduce the population by one logarithm. (TR3) The time in minutes at a specific temperature required to reduce the population of a specific microorganism by 90% [or one (1) log] in defined conditions [e.g., method of sterilization (dry heat versus steam), solute, or carrier]. (TR13)
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D-value (D10 -Value)
The time in minutes required for a one-logarithm, or 90%, reduction of the population of microorganisms used as a biological indicator under specified lethal conditions. (TR51)
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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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Dead Leg
Area of entrapment in a vessel or piping run that could lead to contamination of the product. (TR69)
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Deadlegs
An area of entrapment in the vessel or piping run that could lead to contamination of the product due to insufficient exposure to moist heat. (TR61)
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Decontamination
A process that is designed to remove soil (including microorganisms) and may consist of cleaning and/or disinfection. (TR51)
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Degradation
The breakdown (usually chemical) of material during manufacture, including during and after the cleaning process. (TR49) (TR70)
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Degradation Product
Molecular variants resulting from changes in the desired product or product-related substance brought about over time and/or by the action of light, temperature, pH, water, etc., or by reaction with an excipient and/or the immediate container/ closure system. Such changes may occur because of manufacture and/or storage (e.g., deamidation, oxidation, aggregation, proteolysis). Degradation products may be either product-related substance or product-related impurities. (TR57)
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Deionized Water
Water treated by passing through both cation- and anion-exchange resin beds, or a mixed-resin bed to remove both positive and negative ions. (TR45)
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Depyrogenation
The destruction and/or removal of bacterial endotoxins. A depyrogenation process should demonstrate at least 99.9% or a 3-log endotoxin reduction. (TR3) Removal or destruction of pyrogens. (TR70)
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Detergent
A synthetic wetting agent and emulsifier that can be added to a solvent to improve its cleaning efficiency. (TR70)
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Dirty Hold Time
The time from the end of product manufacturing until the beginning of the cleaning process (also called “soiled hold time”). (TR29)
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Discrete Control Valve
A device designed for on/off operation; fully opened or fully closed. (TR48)
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Disinfectant
A chemical or physical agent that reduces, destroys, or eliminates vegetative forms of harmful microorganisms but not spores. (TR70)
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Disinfection
The destruction of pathogenic and other kinds of microorganisms by thermal or chemical means. (TR51) (TR70) Process of eliminating nearly all recognized pathogenic microorganisms but not necessarily all microbial forms (e.g., bacterial spores) on inanimate objects. (TR69) The chemical or physical inactivation of a bioburden on inanimate surfaces. Typically this requires a minimum three-log (3-log) reduction of vegetative microorganisms and two-log (2-log) reduction for bacterial spore be achieved in validation. (TR13)
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Downstream Side (of Filter)
The effluent side of the process step (filter). (TR45) The filtrate or outlet side of the filter. (TR26)
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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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Dwell Time
The period that items are subjected to a given processing condition. [Synonym: Residence Time] (TR3)
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Dynamic (in operation)
BFS machine line fully operational and filling, with the number of allowed operating personnel present as during normal running conditions. (TR77)