Skip To The Main Content

PDA Glossary

PDA Glossary of Pharmaceutical and Biotechnology Terminology

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.

Browse Terms by Title


Browse Terms by TR #

  • F0

    <p>A term used when the specific reference conditions of T<sub>ref</sub>- = 121.1&deg;C and z = 10&deg;C are used to calculate the equivalent lethality. For example, when the z-value of the BI is 10&deg;C, a cycle with an F(T=121.1&deg;C, z=10&deg;C), or F<sub>0</sub>, equal to 8 minutes is equivalent (in terms of delivered lethality) to a square wave cycle of 8 minutes at 121.1&deg;C. A square wave cycle that provided an exposure of 25.9 minutes at 116&deg;C would also yield an F<sub>0</sub> of 8 minutes.   Note: The reference temperature used in calculating F<sub>0</sub> is 121.1&deg;C, which is the approximate mathematical equivalent of 250°F. (TR01) (TR30) (TR48) (TR61)</p>
  • Facilitator

    Independent QRM expert who facilitates risk assessment; guides documentation, risk control, and risk review; and helps present risk assessment results and risk control proposals. (TR54-2) (TR54-5)

  • Facility

    A physical building with a defined building number or name. (TR38)

  • Factor

    Independent variables that may influence assay outcome. (May be modified with confounded, crossed, fixed, interaction, level, modifying, nested, random). (TR57) (TR57-2)

  • Factory Acceptance Test (FAT)

    A test typically conducted by the sterilizer manufacturer after the system has been assembled and before the system is shipped to the installation site. (TR48) (TR54-5)

  • Failure

    The condition or fact of not achieving expected results; a cessation of proper functioning or performance. (TR44)

  • Failure Effect

    An impact on customer requirements. Generally, failure effect has an external customer focus, but it can also include downstream processes. (TR58)

  • Failure Mode and Effects Analysis (FMEA)

    A method of assessing and evaluating risk. (TR44)

    A systematic method for identifying, analyzing, prioritizing and documenting potential failure modes, their effects on system, product and process performance, and the possible causes of failure in order to prevent defects from occurring. (TR54) (TR54-2) (TR54-3) (TR54-4) (TR74) (TR54-5)

    A tool for analyzing processes or systems to evaluate all operating steps in order to identify and assess the risk associated with any potential failures. (TR65)

    An analytical technique that results in a rankordered list of concerns to take action on. (TR72)

  • 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)

  • 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)

  • FAO (Food and Agriculture Organization)

    The FAO’s mandate is to raise levels of nutrition, improve agricultural productivity, better the lives of rural populations, and contribute to the growth of the world economy. (TR55)

  • Fastidious strain (isolate)

    A population of microorganisms having complex nutritional requirements and thus difficult to cultivate. (TR50)

  • Fault Tree Analysis (FTA)

    A deductive technique used to analyze the causes of faults (defects). The technique visually models how logical relationships between failures, human errors, and external events can combine to cause specific faults. (TR54) (TR54-2) (TR54-3) (TR54-5)

  • FDA Form 483

    Inspectional observation sheet used by FDA investigators to document their findings. (TR67)

  • Fed-Batch Filtration Process

    A modification of the batch filtration process in which a separate (typically larger) reservoir feeds a smaller recycle tank. The retentate stream is returned to the recycle tank. (TR15)

  • Feed

    The starting solution prior to filtration. (TR15)

  • Feed (or Load or Feedstock or Feedstream)

    The fluid introduced into a process. (TR41)

  • Feed Pressure

    The pressure measured at the inlet of the tangential flow filter device. (TR15)

  • Feret Min and Max

    Feret Min is the minimum distance between parallel tangents at opposing particle borders. Feret Max is the maximum distance between parallel tangents at opposing particle borders.

  • Fermentation Broth

    The fluid and all constituents in a fermentation vessel prior to separation. (TR45)

  • Filter

    A porous medium used for the separation of components in a fluid stream.(TR15)

  • Filter (noun)

    A device used to remove particles from a fluid process stream that consists of a porous medium and a support structure. Porous material through which a liquid or gas is passed to remove viable and non-viable particles.(TR26)

  • Filter (verb)

    To pass a fluid through a porous medium whereby bacteria or other particles are removed from the fluid. (TR26)

  • Filter Area

    The effective surface area of a filter that is available for filtration; not the internal pore surface area, but rather the surface of one side of a filter. (TR45)

  • Filter Efficiency

    A measurement of how well a filter retains particles. It is usually expressed as the percentage, or ratio, of the retention of particles of a specific size by a filter. (TR26)

  • Filter Element

    The basic filter unit from which cartridges or capsules are assembled. (TR26)

  • Filter Rating

    A numerical rating of filter performance based on the ability of the filter to retain an appropriate model microorganism under given test conditions. (TR75)

  • Filterability Test

    A test to determine the suitability and sizing of a filter with a given fluid. (TR26)

  • Filtrate

    Fluid that has been passed through a process step (filter). [Synonym: Permeate] (TR15) (TR26)

  • Filtrate Pressure

    The pressure measured at the outlet side of the tangential flow filter device containing filtered material. [Synonym: permeate pressure] (TR15)

  • Filtration

    A process of removing particles from a fluid by passing it through a permeable material, such as a membrane film. (TR41)

    The process by which particles are removed from a fluid by passing the fluid through a porous material. (TR26)

  • 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)

  • 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)

  • First Air (First Work Location)

    The work location first in the path of HEPA filtered air. (TR62)

  • First Expiration, First Out (FeFo)

    A method of controlling inventory to ensure that the material with the shortest remaining shelf-life is distributed first. (TR52)

  • Flexible 2D or 3D Bag

    A flexible-wall container designed with 2 sides (two dimensional or “pillow” shape) or 6 sides (three dimensional cuboid shape) designed to hold process fluids or product. (TR66)

  • Flow Decay

    Decrease in flow rate at constant pressure as a result of filter fouling. (TR45)

  • Flow Decay Test

    An experiment to determine flow rate and throughput of a filter type or combination of filters on a specific liquid, usually by using a small area filter, to determine the sizing of a filter system by extrapolation. (TR45)

  • Flow Rate

    The volumetric rate of flow of a solution, expressed in units of volume per time (e.g., L/min or gal/day). (TR15) (TR26)

  • Flow-through

    Effluent that may contain the product that is not retained by chromatography resin during column loading. (TR14)

  • Flux

    The rate of transfer of fluid through a cross-sectional area often applied to filtrate flow rate; expressed in units of volume per time per unit area (e.g., LMH: liters per square meter per hour). (TR15)

    The rate of filtrate flow divided by the membrane area. (TR26)

  • Flux Decay

    Instantaneous or current flux relative to initial or buffer flux. (TR41)

  • 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)

  • Formal Experimental Design (Synonym – Design of Experiments)

    A structured, organized method for determining the relationship between factors affecting a process and the output of that process. (TR60)

  • Formative Usability Evaluation

    Observed actual or simulated use of early prototypes to help reliably identify product conceptspecific, use-related hazards that may have been missed by other methods. (TR73)

  • Formulation

    A listing of the ingredients and composition of the dosage form. (TR38) The percent composition of ingredients in a product. (TR67)

  • Foulant

    Solute or suspended solid that interacts with the membrane causing a decrease in performance (see Fouling). (TR15)

  • Fouling (or Clogging)

    Adsorption or interaction with components in the feed stream resulting in a decrease in membrane performance. Generally, fouling can be reversed by cleaning the membrane. (TR15)

    The result of solutes blinding or blocking membrane pores. It is observed as a decrease in the flux (at constant pressure) or an increase in the filtration differential pressure (at constant flux). (TR26)

  • 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)

  • 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)

  • Free Drained Equipment

    No visible water pool in the equipment or line when viewed under appropriate lighting conditions (but may contain water droplets). (TR29)

  • Freeze-Thaw

    A study designed to determine the effect of repeated freezing (typically to -20 °C), and thawing back to labeled storage conditions (typically +5 °C for refrigerated products, and +25 °C for temperature products). Freeze-thaw studies are designed to evaluate the impact of short-term excursions where product may be exposed to sub-zero temperatures, followed by standard shipping conditions. (TR53)

  • 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)

  • Frit

    A porous sieve or screen installed at the top and bottom of a column used to retain chromatography resin particles and allow passage of the process stream. [Synonym: sinter] (TR14)

  • Full Loop Calibration

    A calibration process that includes all measurement system components, from sensor to measurement value (e.g., temperature calibration of a data logger and attached thermocouple wires). (TR64)

  • Fumigation of Wood Pallets

    The currently approved International Standards for Phytosanitary Measures (ISPM) fumigation method is methyl bromide (MB) fumigation and is one of the two approved phytosanitary measures in ISPM 15 (treatment and marking of wood packaging materials [WPM] that is required for international shipment. The use of methyl bromide is not permitted in some IPPC countries (e.g. the EU), and the latest ISPM 15 standard has a recommendation to reduce its use. Note: Steam heat treatment is the other ISPM 15 approved method. (TR55)

  • 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)

  • 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)

  • 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)

  • 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)

  • F-Value (Lethality Factor) -- F-Value for Depyrogenation

    The term F-value may also be used in dryheat depyrogenation processes to calculate the time in minutes equivalent to a lethality or endotoxin destruction effect delivered by dry heat at 250°C. The F-value reference temperature is set at 250°C and the z-value minimum is set at 46.4°C. (TR3)

  • 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)