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 47: Virus Spikes/Virus Clearance (1)
- TR 51: Biological Indicators (1)
- TR 55: TBA/TCA Detection Mitigation (1)
- TR 60: Process Validation (1)
- TR 62: Manual Aseptic Processes (1)
- TR 65: Technology Transfer (1)
- TR 67: Objectionable Microorganisms (1)
- TR 3: Validation: Dry Heat (1)
- TR 60-2: Process Validation: A Lifecycle Approach, Annex 1: Oral Solid Dosage/Semisolid Dosage Forms (1)
- TR 45: Depth Filtration (1)
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Water Activity (Aw)
Water Activity, Aw is the ratio of the vapor pressure of water in a product (P) to the vapor pressure of water in a product (P) to the vapor pressure of pure water (Po) at the same temperature. It is numerically equal to 1/100 of the RH generated by the product in a closed system. It is a measure of the free or available moisture in the material. Note: Water activity ≠ water content. RH can be calculated from direct measurements partial vapor pressure or dew point, or from indirect measurements by sensors whose physical or electric characteristics are altered by the RH to which they are exposed. Microorganisms need available water within a pharmaceutical product, as well as nutrients and minerals, to proliferate. Water activity, and not water content, is a better measure of the free water, in contrast to bound water that microbial cells require for metabolic activity and osmotic regulation. Effects of reduced Aw on microbial growth include a longer lag phase, slower growth rate, lower numbers of organisms in the stationary phase, and reduced microbial toxin production; below a specified Aw for an organism, microbial growth will not occur. (TR55) (TR67)
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Water for Bacterial Endotoxin Test (BET)
Sterile Water for Injection or other water that shows no reaction with the specific bacterial endotoxin test reagent with which it is to be used, at the limit of sensitivity of such reagent. (TR3)
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Water for Injection (WFI)
Water purified by distillation or a purification process that is equivalent or superior to distillation in the removal of chemicals and microorganisms and contains no added substances. (TR45)
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Work Breakdown Structure (WBS)
A hierarchical and incremental decomposition of a project into phases, deliverables, and work packages; commonly a tree structure that shows a subdivision of effort required to achieve an objective. (TR65)
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Working Cell Bank (WCB)/Working Virus Bank (WVB)
A stock of cells or virus derived from the MCB/MVB and used to produce production cells, assay cells or virus production lots. (TR 47)
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Working Seed Lot
A seed lot generated from the master seed stock by a single passage. (TR51)
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Worst Case
A set of conditions encompassing upper and lower processing limits and circumstances, including those within standard operating procedures, that pose the greatest chance of process or product failure (when compared to ideal conditions). Such conditions do not necessarily induce product or process failure. (TR60)
A set of conditions encompassing upper and lower processing limits and circumstances, including those within standard operating procedures, that pose the greatest chance of process or product failure (when compared to ideal conditions). Such conditions do not necessarily induce product or process failure. (TR62) (TR60-2)