PDA Technical Glossary

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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Analytical Method Transfer (AMT)
Documented process that qualifies a laboratory (receiving unit) to use an analytical test procedure that originates in another laboratory (the transferring unit, also known as the sending unit), thus ensuring that the receiving unit has the knowledge and ability to perform the transferred analytical procedure as intended. (TR57-2)
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Analytical Platform Technology (APT)
An analytical method that is used for multiple products and/or types of sample matrix without modification of the procedure. Similar to compendial methods, an APT method may not require full validation for each new product or sample type. (TR57)
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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)
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Batch Filtration Process
In a batch filtration process, the entire volume to be filtered is held in a single feed tank. The retentate stream is recycled back to that single feed tank. (TR15)
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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)
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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)
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Correlation Coefficient ( r )
A measure of covariation, the square root of the coefficient of determination. (TR57)
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Critical Process (CP)
A process that impacts a critical quality attribute of the intermediate, drug substance or drug product being manufactured and therefore should have established critical process parameters that can be monitored or controlled to ensure that the process produces the desired quality.
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Cycle Development
A series of activities performed for the purpose of defining or confirming the cycle parameters (e.g., time, temperature, pressure) necessary to ensure sanitization or sterilization. (TR61)
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Cycle Phases
A discrete series of sterilizer process steps (such as, heat-up, exposure and cool-down) performed sequentially that represent a complete sterilization cycle. (TR48)
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Darcy Permeability
The constant of proportionality of the material as defined by Darcy’s Law. (TR45)
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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)
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Exclusivity
The capacity of an assay not to detect microorganisms closely related to a target microorganism. (TR33)
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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)
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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)
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Method Development
A process that involves the selection, optimization, and qualification of a physical/chemical, biological, molecular, or microbiological test procedure. (TR57)
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Method Lifecycle
All stages in the life of a method, from the initial development through marketing, until the method’s discontinuation. (TR57-2)
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Method Parameter
Any factor or method operational step that can be varied continuously (e.g., flow rate) or specified at controllable unique levels (e.g., Gas Chromatograph liner type).
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Method Qualification
Formal or informal study performed to assess initial method performance prior to full ICH Q2 (R1) validation; assessment activity that cul­minates in a scientifically sound method that has an acceptable level of performance and is docu­mented to be suitable for its intended use. (TR56) Experimental studies performed to confirm the inherent performance capabilities of a test method for the material being analyzed and the intended use of the method. Method qualification can be performed during early development phases, prior to method validation. Specific method qualification characteristics (e.g., accuracy, specificity) should be confirmed based on the intended use of the analytical method and the relevant risk(s). (TR57)
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Method Validation
A formal, archived demonstration of the analyti­cal capacity of an assay that provides justification for use of the assay for an intended purpose. (TR56) A formal, archived demonstration of the analytical capacity of an assay that provides justification for use of the assay for an intended purpose. Validations are conducted prospectively according to a written, approved plan that states acceptance criteria. (TR57) (TR57-2)
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Method, Qualitative
An analytical procedure, based on the characteristics of a material that yields results that are not amenable to reliable enumeration. (TR57)
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Method, Quantitative
An analytical procedure that yields numerical results compared to quantitative specification(s). (TR57)
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Minimum Acceptable Cycle (MAC)
The minimum cycle conditions (in terms of delivered minimum lethality or minimum time and temperature) that would be considered acceptable. (TR01) (TR61)
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Mixed Load
A load that contains multiple item item types representing various sterilization challenges. For example, some load items may have air removal challenges, while others pose a challenge due to their mass. (TR01)
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Optical Density (OD)
A unitless measure of the absorption of light of a given wavelength in media of a given path length. (TR41)
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Polymerase Chain Reaction (PCR)
A technique widely used in molecular biology in which a DNA polymerase is used to amplify a piece of DNA by in vitro enzymatic replication. As PCR progresses, the DNA thus generated is itself used as a template for replication. This sets in motion a chain reaction in which the DNA template is exponentially amplified. This technique may be used to quantify virus. (TR41) (TR47)
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Precision
The degree of agreement among individual test results when the procedure is applied repeatedly to multiple samplings of the same suspension of microorganisms and using different suspensions across the range of the test. Also known as repeatability. (TR33) The closeness of agreement (degree of scatter) between a series of measurements obtained from multiple sampling of the same homogeneous sample under the prescribed conditions. Precision may be considered at three levels: repeatability, intermediate precision, and reproducibility. It is usually expressed as the variance, standard deviation, or coefficient of variation of a series of measurements. (TR57)
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Precision, Intermediate
The closeness of agreement between a series of measurements obtained within laboratory variations (e.g., different days, different analysts, different equipment). (TR57)
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Precision, Reproducibility
The closeness of agreement between a series of measurements for the same sample obtained among different laboratories. (TR57)
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Primer
A short synthetic single-stranded nucleic acid complementary to a specific sequence of a target gene, DNA or RNA. It usually serves to initiate the de novo synthesis of nucleic acid from a template. (TR50)
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Product Changeover
Procedural steps taken for switching from the manufacturing of one product to another product. (TR29)
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Reference Strain
A well characterized, widely accepted preparation of viable organisms that is used to validate a microbiological assay. (TR50)
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Relevant Virus
A virus used in process evaluation studies that either is the identified virus, or of the same species as the virus known to or likely to contaminate the cell substrate or any other reagents or materials used in the production process. (TR41)
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Reporter Gene
A coding sequence linked to a gene or promoter of interest. It is generally used to determine activation of the promoter or expression of the gene of interest in a cell or organism. (TR50)
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Screening Studies
Studies used to select a particular type and grade of filter media. (TR45)
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