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 60: Process Validation (5)
- TR 51: Biological Indicators (4)
- TR 57: Analytical Method Validation (3)
- TR 70: Cleaning/Disinfection Programs (3)
- TR 1: Validation: Moist Heat (3)
- TR 3: Validation: Dry Heat (3)
- TR 14: Validation: Protein Purification Chromatography (3)
- TR 88: Microbial Data Deviation Investigations in the Pharmaceutical Industry (3)
- TR 57-2: Analytical Method Development (2)
- TR 58: Temp Controlled Distribution (2)
- TR 61: Steam in Place (2)
- TR 67: Objectionable Microorganisms (2)
- TR 68: Drug Shortage Management (2)
- TR 69: Bioburden/Biofilm Management (2)
- TR 74: Reprocessing of Biopharmaceuticals (2)
- TR 13: Environmental Monitoring (2)
- TR 29: Validation: Cleaning (2)
- TR 54-5: Quality Risk Management for the Design, Qualification, and Operation of Manufacturing Systems (2)
- TR 42: Validation: Protein Manufacturing (2)
- TR 47: Virus Spikes/Virus Clearance (1)
- TR 48: Moist Heat Sterilizer Systems (1)
- TR 53: Stability Testing New Drug Products (1)
- TR 54-2: QRM: Packaging Labeling (1)
- TR 54-3: QRM: Drug Products (1)
- TR 54-4: QRM: Biotech Drug Substance (1)
- TR 56: Phase Appropriate cGMP Application (1)
- TR 26: Sterilizing Filtration of Liquids (1)
- TR 38: Manufacturing Chromatography Systems Postapproval Changes (ChromPAC) (1)
- TR 30: Parametric Release (1)
- TR 41: Virus Filtration (1)
- TR 43: Glass Defects (1)
- TR 44: QRM: Aseptic Processes (1)
- TR 45: Depth Filtration (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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Darcy Permeability
The constant of proportionality of the material as defined by Darcy’s Law. (TR45)
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Date of Manufacture
For small molecules, the date of manufacture of a drug product is considered to be the initial date that an active ingredient has been added during manufacturing. For biologics the date of manufacture can be determined in multiple ways and should be consistent with internal quality systems and the product license application. (TR53)
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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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Dedicated Equipment
Equipment used exclusively for the manufacture of only one drug product, bulk drug substance, or intermediate. (TR29)
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Defect
(1) A departure of a quality characteristic from its intended level or state that occurs with a severity sufficient to cause an associated product or service not to satisfy its intended normal or foreseeable usage requirements. (TR51) (2) The nonfulfillment of intended usage requirements. The departure or absence of one or more quality characteristics from intended usage requirements. (TR43)
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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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Design Reviews
Planned and systematic reviews of specifications, design, and design development and continuous improvement changes performed as appropriate throughout the lifecycle of the manufacturing system. Design reviews evaluate deliverables against standards and requirements, identify problems, and propose required corrective actions. (TR54-5)
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Design Space
The multidimensional combination and interaction of input variables (e.g., material attributes) and operational parameters that have been demonstrated demonstrated to provide assurance of quality. Working within the design space is not considered as a change. Movement out of the design space is considered to be a change and would normally initiate a regulatory post approval change process. Design space is proposed by the applicant and is subject to regulatory assessment and approval. (TR30) (TR60) (TR 57-2)
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Design Specification
Controlled documentation that clearly and explicitly defines the manufacturing system details, codes, and standards to be followed during fabrication and construction to meet associated requirements. (TR54-5)
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Design of Experiments (DOE)
A method for carrying out carefully planned experiments on a process. Usually, DoE involves a series of experiments that initially involves evaluating many variables and then focuses on a few critical ones. (TR54-4)
A structured, organized method for determining the relationship between factors affecting an assay and output of that assay. (TR57) (TR57-2) (TR74)
A structured, organized method for determining the relationship between factors affecting a process and the output of that process (8). (TR60)
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Detectability (D)
The ability to discover or determine the existence, presence, or fact of a hazard. (TR54-2) (TR54-3)
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Detection
The ability to discover or identify a defect or failure. (TR44)
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Development Reports
Documentation and description of work done during the early phases of development. The goal is to document information about the way the process works and to document why key choices were made in selecting the specifics of the process (e.g., flow rate or temperature). These documents can serve as a reference during investigations of discrepancies and during the design of specific Validation and characterization studies.(TR14) (TR 42)
Documentation and description of work done during the early phases of development (Stage 1). The goal is to document information about the way the process works and to document why key choices were made in selecting the specifics of the process (e.g., flow rate or temperature). These documents can serve as a reference during investigations of deviations and during the design of specific validation and process characterization studies.(TR60)
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Deviation
Departure or digression from set parameters. (TR58)
Data or a result outside of the expected range or an unfulfilled requirement; it may be called nonconformity, defect, discrepancy, out-of-specification, out-of-limit, or adverse trend. (TR88)
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Diffusive Flow
The movement of a dissolved gas across a liquidwetted membrane based on the concentration (e.g., gas pressure) differential. (TR26)
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Direct Flow Filtration (DFF) or Normal Flow Filtration (NFF)
In direct flow filtration, all fluid is directed through the membrane in a single pass. (TR41)
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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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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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Distribution Testing
Qualification of packaging components for physical distribution integrity like shock, vibration, and drop tests. (TR58)
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Drug Product (DP)
A pharmaceutical product type that contains a drug substance, generally, in association with excipients. [Synonym: Dosage Form; Finished Product] (TR57)(TR14)(TR42)
A finished dosage form (e.g., tablet, capsule, or solution) that contains a drug substance, generally, but not necessarily, in association with one or more other ingredients.(TR38) (TR67) (TR88)
The dosage form in the final immediate packaging intended for marketing.(TR60)(TR82)
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Drug Shortage Prevention & Response Plan
A document that provides a structured action plan to proactively prevent drug shortages and also respond to a shortage in the event that one occurs. (TR68)
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Drug Shortage Risk Register
A single source of information on risks that can result in drug shortages, associated risk levels, risk control actions with owners, status, due dates and residual risk after appropriate risk control actions have been taken. (TR68)
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Drug Substance (DS)
The active ingredient that is subsequently formulated with excipients to produce the drug product. It can be composed of the desired product, product-related substances, and product- and process-related impurities. It may also contain excipients, including buffers and other components. [Synonyms: bulk drug substance, bulk material, active pharmaceutical ingredient (API)] (TR14) (TR57) (TR74) (TR60)
Active pharmaceutical ingredient in a drug product that is responsible for that product’s therapeutic activity.(TR67) (TR82) (TR88)
See Active Pharmaceutical Ingredient (API). (TR56)
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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 Light Scattering (DLS)
A technique used to measure the size and size distribution of particles. Particles suspended in a solution will cause scattering of light and the extent of the scattering is related to the size and shape of the particles. (TR47)