Working Cell Bank (WCB)
The WCB is derived from one or more vials of cells from the MCB, which are expanded by serial subculture. The pooled cells are dispensed into individual vials and cryopreserved to form the WCB. (TR54-4)
The WCB is derived from one or more vials of cells from the MCB, which are expanded by serial subculture. The pooled cells are dispensed into individual vials and cryopreserved and stored in the vapor phase of liquid nitrogen. (TR83)
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Wash
Step in a chromatography cycle designed to flush the column to remove substances acquired during a previous step (often used between the load and elution steps). (TR14)
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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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Warning Letters
Type of correspondence that notifies a regulated industry about violations that FDA has documented during its inspections or investigations. (TR67)
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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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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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Worst-Case Conditions
A set of conditions encompassing upper and lower processing limits and circumstances, including those within standard operating procedures, which pose the greatest chance of process or product failure when compared to ideal conditions. Such conditions do not necessarily induce product or process failure. (TR28)
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Worst-Case Process Condition
A condition or set of conditions encompassing upper and/or lower processing limits and circumstances, within standard operating procedures, which pose the greatest chance of product or process failure when compared to ideal conditions (such conditions do not necessarily induce product or process failure). (TR29)
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Worst Case Soil
A soil that is the most difficult to clean from production equipment based on knowledge generated from laboratory studies, scientific properties, and/or production experience. (TR29)
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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)
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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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