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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 #

  • Backstop (Finger Plate or Thumb Plate)

    Feature that enhances the area to hold the syringe and is usually designed to avoid accidental removal of the plunger from the back. By design, it may also serve as a flange extender to facilitate holding of the syringe during injection. (TR 73)

  • Backup (FDA)

    A true copy of the original data that is maintained securely throughout the records retention period. The backup file should contain the data (which includes associated metadata) and should be in the original format or in a format compatible with the original format.(TR80)

  • Backup (MHRA)

    A copy of current (editable) data, metadata and system configuration settings maintained for recovery including disaster recovery.(TR80)

  • Backup (WHO)

    A copy of one or more electronic files created as an alternative in case the original data or system are lost or become unusable. Backup differs from archival in that back-up copies of electronic records are typically only temporarily stored for the purposes of disaster recovery and may be periodically overwritten. Such temporary back-up copies should not be relied upon as an archival mechanism.(TR80)

  • Bacteria

    Single-celled, microscopic organisms typically with a cell wall and characteristic shape (e.g., round, rod-like, spiral or filamentous); lacking a defined nucleus (“prokaryotic”). (TR26)

  • Bacterial Endotoxin

    Endotoxins are fever producing substances commonly found in the cell wall of certain Gram-negative bacteria. (TR3)

  • Bacterial Endotoxin Test (BET)

    Assay for measuring active endotoxin by combining a liquid test sample with Limulus amebocyte lysate (LAL) reagent and measuring the resulting proportional reaction via visual, turbidimetric, chromogenic, or other validated means of detection. (TR3)

  • Bacteriophage

    A bacteriophage is any one of a number of viruses that infect bacteria. The term is commonly used in its shortened form, “phage”. (TR41) (TR 47)

  • Ballotini

    Small glass beads (spheres) obtainable in a range of sizes, used in the recovery of spores from paper carriers. (TR51)

  • Barrier System

    A system of physical partitions that affords ISO 5 protection by partially separating its interior from the surrounding environment utilizing airflow. (TR22) (TR62)

  • Batch Oven

    A convection oven with a chamber or chambers where items are dry-heat sterilized or depyrogenated as a single load in a discontinuous process. The oven typically uses one or more filters to remove air particles. (TR3)

  • Batch Process

    A process where there are no streams flowing into or out of a controlled volume, as opposed to a continuous process. In a batch filtration process, the feed solution is reduced in volume due to permeation of filtrate through the filter. There is no continuous addition of feed solution to the feed vessel. (TR45)

  • Beta Glucans [(1→3)-β-D-glucans] (BG)

    Homopolymers of glucose connected by (1→3)-β-D- glycosidic linkages. (TR45)

  • Bias

    A systematic difference in a method that manifests itself as a deviation of the method mean from an expected value. (TR57)

    Total systematic error, in contrast to random error. Measurement centered on the true result is said to be unbiased or have no systematic error. The distance between the center of a large (infinite) number of measurements and the correct value is the bias. (TR 57-2)

  • Bioanalytical Test Method

    A method used to assess the presence of analytes (chemical or biological) in biological samples (e.g., serum, plasma, etc.). (TR57)

  • Bioassay

    Analysis (as of a drug) to quantify the biological activity(ies) of one or more components by determining its capacity for producing an expected biological activity. (TR57)

  • Bioburden

    The total number of microorganisms per unit of material prior to sterilization. (TR13)

    Total number of viable microorganisms on or in a health care product prior to sterilization. (TR22)(TR61)(TR62)

    A population of viable microorganisms in a fluid prior to sterilizing filtration. (TR26)

    A measure of the contaminating organisms found in or on a given amount of material before it undergoes a sterilization process. (TR45) (TR70)

    The number of detectable microorganisms (bacteria and fungi) with which an object is contaminated. It is measured in CFU (colony forming units). (TR47)

    The number of viable, contaminating microorganisms present on a product immediately prior to decontamination. (TR51)

    Viable microbial contaminants associated with personnel manufacturing environments (air and surfaces), equipment, product packaging, raw materials (including water), in-process materials, and finished products. (TR 67) (TR 69)

  • Biocide

    Chemical substance that has been proven to kill specific microorganisms common in the pharmaceutical manufacturing environment. (TR 69)

  • Biofilm

    Microbially derived sessile community characterized by cells that are irreversibly attached to a substratum, interface, or each other; are embedded in a matrix of extracellular polymeric substances (EPSs) that they produce; and exhibit an altered phenotype with respect to growth rate and gene transcription. (TR 69)

  • Biofouling (or Biological Fouling)

    Accumulation and subsequent deleterious effects of biological contaminants on engineered products or processes (TR 69)

  • Biological Active Substance

    Manufactured biological active substances and medicinal products involving biological process­es and materials, such as cultivation of cells or extraction from living organisms. (TR56)

  • Biological Activity

    Property that describes the specific ability or capacity of a product to achieve a defined biological effect. (TR57)

  • Biological Indicator (BI)

    An inoculated carrier contained within its primary pack ready for use and providing a defined resistance to the specified sterilization process. (TR51)

  • Biological Indicator (BI) Challenge System

    A test system containing viable microorganisms of a pure and specified strain providing a defined resistance to a specified sterilization process (TR1)(TR3) (TR30) (TR61)

  • Biological Medicinal Product

    A product (therapeutic or prophylactic) for human use that has been manufactured in or from a biological source. Examples include recombinant therapeutic proteins or vaccines. Biological medicinal products are also referred to as: biological medicines, biological products, biologics and biologic drugs. (TR 71)

  • Biological Qualification

    A component of performance qualification that demonstrates, by use of biological indicators, that the required lethality (FBIO) is achieved consistently throughout the load. (TR1) (TR3) (TR30)

    A component of performance qualification that demonstrates, by use of biological indicators, that the required lethality (FBIO) or spore log reduction (SLR) is achieved consistently throughout the sterilized or sanitized portion of the SIP system. (TR61)

  • Biological Safety Cabinet (BSC)

    An enclosed, ventilated workspace with engineering controls designed to remove or minimize exposure to hazardous biological materials. A BSC is a principle device to provide containment of infectious splashes or aerosols generated by many microbiological procedures. BSCs are designed to provide personnel, environmental and product protection when appropriate practices and procedures are followed. A cabinet that is designed to protect the operator and the environment from the hazards of handling infected material and other dangerous biological. (TR62)

  • Biological Tests

    Biological tests include animal, cell culture, or biochemical based testing that measures a biological, biochemical, or physiological response. (TR38)

  • Biologics License Application (BLA)

    An application, filed with the US Food and Drug Administration (FDA), which contains specific information on the manufacturing processes, chemistry, pharmacology, clinical pharmacology and the medical effects of the biologic product (similar function as the Marketing Authorization Application in Europe). (TR56)

  • Biomethylation

    The enzyme chlorophenol o-methyltransferase responsible for fungal methylation has been isolated in cell-free extracts. Biomethylation, in this context, may be seen as a detoxification mechanism, although it plays a role in the production of mycotoxins by secondary metabolism. Slightly xerophilic fungi frequently associated halophenol biomethylation include Trichoderma longibrachiatum, Trichoderma virgatum, Aspergillus sydowii, and Penicillium islandicum. (TR55)

  • Blank

    Analytical sample taken to establish background value for the analytical measurement which may be subtracted from an experimental value to determine the “true” value. (TR29) (TR49)


    Basic Local Alignment Search Tool; a bioinformatics algorithm for the comparison of sequence data (e.g., translated amino acids [tBLASTx], proteins [BLASTx], or nucleotides [BLASTn]). (TR 71)

  • Block Pallet

    A type of pallet with blocks between the pallet decks or beneath the top deck. These types of pallets usually carry more loads and last longer than stringer and typically 4 way entry. (TR55)

  • Blocking

    The grouping of related experimental units used in design of experiments (DOE). (TR57)

  • Boundary Layer

    A thin layer of fluid near the membrane surface in which the tangential velocity changes from zero at the surface to the free stream value away from the surface. (TR15)

    Coating of fluid in the immediate vicinity of a bounding surface where the effects of viscosity are significant (TR 69)

  • Bracketing

    A demonstration of unit operation performance at two different values of a given parameter (e.g., ionic strength, dwell time or temperature), allowing the use any values of that parameter falling within this range. (TR41)

  • Bracketing Approach

    A scientific approach for defining product/load characteristics (e.g., viscosity, container sizes, container fill volumes, item sizes, loading configurations) that are tested (in a qualification study or validation study) at upper and/or lower limits. (TR1) (TR61)

    A validation method that tests the extremes of a process or product. The method assumes the extremes will be representative of all the samples between the extremes. (TR26)

  • Break-loose Force

    Energy required to initiate plunger movement within the syringe barrel upon injection. (TR 73)

  • Breakthrough Limited

    A filtration operation resulting in a significant rise in filtrate turbidity accompanied by a small increase in differential pressure. This occurs when the adsorptive capacity of the filter is reached, resulting in the passage of particles smaller than the pore size of the filter that would normally be removed by adsorption. (TR45)

  • Brevundimonas Diminuta (B. diminuta)

    Small bacteria (0.3–0.4 &;mum in diameter by 0.6–0.1 &;mum long) used to challenge a sterilizing grade filter during validation testing. [Formerly Pseudomonas diminuta](TR45)

  • British Thermal Unit (BTU)

    The amount of heat (measured in Joules) required to raise the temperature of one pound of water by 1ºF.(TR64)

  • Bubble Point

    The measured differential gas pressure at which a wetting liquid (e.g., water, alcohol, product) is pushed out of the largest pores of a wetted porous membrane, and a steady stream of gas bubbles or bulk gas flow is detected.(TR15) (TR26)

    The minimum pressure at which a wetting liquid is pressed out of the pore system of a membrane while forming a steady bubble chain. (TR41)

  • Bubble Point Test

    A test to indicate the maximum pore size of a filter. The differential gas pressure at which a liquid (usually water) is pushed out of the largest pores and a steady stream of gas bubbles is detected from a previously wetted filter under specific test conditions. Used to test filter integrity with specific, validated, pressure values, wetting liquids and temperatures for specific pore-size (and type of ) filters. (TR26)

  • Bulk Packaged Product

    Consists of solid, liquid, or frozen product in a bulk container configuration such as a bag, tank, or drum. The product may be in these container configurations between process steps or prior to filling into vials, ampoules, cartridges, or syringes. (TR39)