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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 #

  • Accelerated Stability Testing

    Studies designed to increase the rate of chemical degradation or physical change of a drug substance or drug product by using exaggerated storage conditions as part of the formal stability studies. (TR57-2)

  • Analytical Control

    Material used to monitor the performance of a method to assess the integrity and validity of the results. (TR57-2)

  • Analytical Method Design

    Collection of activities performed to define the intended purpose of the method, select the appropriate technology to implement the method, and identify the critical method variables that need to be controlled to ensure that the method is robust and rugged. (TR57-2)

  • Analytical Method Development (AMD)

    Collection of activities performed to select an appropriate technique and method conditions to meet the Analytical Target Profile (ATP) requirements. (TR57-2)

  • Analytical Method Qualification (AMQ)

    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, is documented to be suitable for its intended use, and is demonstrated to have “adequate capability … to meet appropriate standards of performance for its purpose” (TR57-2)

  • 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)

  • Analytical Target Profile (ATP)

    Set of predefined method parameters and performance requirements that help identify the type of method desired relative to method categories (identity, purity, and impurity) defined in ICH Q2(R1) as well as the necessary method performance attributes, such as accuracy, precision, and specificity. (TR57-2)

  • 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)

  • Characterization Method

    Scientifically sound method of a generally complex nature that is used for nonroutine assessment of specific biochemical, chemical, physicochemical, immunochemical, microbiological, and biological characteristics or inherent properties of a compound. (TR 57-2)

  • Comparative Transfer

    Transfer of a method that involves the analysis of a predetermined number of samples of the same lot by both the sending and the receiving unit. (TR 57-2)

  • Confidence Interval

    An interval estimate (range of values) of a population parameter, calculated from a random sample of the underlying population. (TR57)

    Interval estimate (range of values) of a population parameter calculated from a random sample of the underlying population that represents the likely range in which the true value of the parameter resides. (TR57-2)

  • Critical Quality Attribute (CQA)

    A physical, chemical, biological, or microbiological property or characteristic that should be within an appropriate limit, range, or distribution to ensure the desired product quality. (TR14)(TR54)(TR54-4)(TR57)(TR57-2)(TR60)(TR01)

    Product attributes that affect product safety, identity, strength, quality and purity.(TR15)

    Attributes that describe a parameter or item that must be controlled within predetermined criteria to ensure that the medicinal product meets its specifications .(TR39)

    A defining characteristic of the product, including purity, strength, identity and safety.(TR44)

    A physical, chemical, biological or microbiological property or characteristic that should be within an appropriate limit, range, or distribution to ensure the desired product quality.(TR74)(TR 54-5)(TR81)

    A physical, chemical, biological or microbio­logical property or characteristic that should be within an appropriate limit, range, or distribu­tion to ensure the desired product quality, as de­fined in ICH Quality Guidance Q8. (TR56)

    A physical, chemical, biological, or microbio­logical property or characteristic that should be within an appropriate limit, range, or distribu­tion to ensure the desired product quality. (TR60-2)

  • Critical Reagent

    A component of the test method that may have a substantial impact on the consistency and reliability of method performance. Features of critical reagents include: 1. A reagent that requires qualification of each new batch prior to routine use in an analytical procedure, or 2. A material whose method performance characteristics may change over time, during handling, or from lot to lot. 3. An analytical reagent that may be purchased only from a single vendor. Reagent Examples: antibodies or enzymes that require titration prior to use, tissue culture treated plates when only one vendor’s plates give acceptable results for a bioassay, growth factors for bioassay cells, conjugated proteins that require custom preparations, or reference or system suitability standards. (TR57)

    Function related: assay reagents that have been shown through development and/or robustness studies to have the potential to generate measurable differences that can significantly affect assay performance, such as sensitivity, specificity, and precision. (TR57-2)

  • 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)

  • 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)

  • Equivalence Test

    Test of conformance to interval-based target acceptance criteria; differs from most common statistical tests in the nature of the statistical hypothesis. In equivalence testing, the alternative hypothesis is that the difference is sufficiently small that no important difference exists. A common statistical procedure used for equivalence testing is the two one-sided T-test. (TR57-2)

  • Factor

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

  • In-Process Method (In-Process Control)

    Checks performed during production to monitor and, if appropriate, adjust the process to ensure that the intermediate or active pharmaceutical ingredient conforms to its specifications. (TR57-2)

  • Matrix Effect

    The direct or indirect alteration or interference in response due to the presence of additional sample components due to sample preparation (for analysis) or other interfering substances in the sample (product related excipients or residuals). (TR57) (TR57-2)

  • Method Lifecycle

    All stages in the life of a method, from the initial development through marketing, until the method’s discontinuation. (TR57-2)

  • Method Operating Space

    Proven acceptable ranges of a method based on knowledge of the effects of critical instrument and procedural parameters on method performance within the design space. (TR57-2)

  • 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)

  • Platform-Based Method

    Existing method based on the same basic principles and steps as a new method that is required and defined in the design/strategy phase; applies to multiple sample types and requires minimal changes or refinements based on specific product requirements. (TR57-2)

  • Primary (Gold-Standard) Reference Standard

    Substance shown by extensive analytical testing to be authentic, representative material; can be
    1) obtained from an officially recognized source,
    2) prepared by independent synthesis,
    3) obtained from existing production material, or
    4) prepared by further purification of existing product material; is representative of the production process, so distinct reference materials for product-related substances, product-related impurities, and process-related impurities may need to be established. (TR57-2)

  • Quality Attribute

    A molecular or product characteristic that is selected for its ability to help indicate the quality of the product, such as identity, purity, potency stability and safety. (TR57) (TR57-2)

    A molecular or product characteristic that is selected for its ability to indicate the quality of the product. Collectively, the quality attributes define identity, purity, potency, and stability of the product, and safety with respect to adventi­tious agents. Specifications measure a selected subset of the quality attributes. (TR60-2)

  • Quality by Design (QbD)

    QbD is utilization of a more systematic and scientific approach to development for enhanced process understanding, so that better controls may be implemented. (TR54-4)

    A systematic approach to development that begins with predefined objectives and emphasizes product and process understanding and process control, based on sound science and quality risk management. (TR60)(TR80) 

    Framework enabling the attainment of the desired state; systematic approach to development that begins with predefined objectives and that emphasizes product and process understanding and process control based on sound science and quality risk management. (TR57-2)

  • Relative Accuracy

    Attribute determined after demonstration of precision, linearity, and specificity under deliberately varied conditions, such as across a range of sample dilutions in the presence of matrix interference. (TR57-2)

  • Residual Fit

    Signed difference between an observed value and the fitted value used to detect nonlinearity, unequal variances, and outliers. (TR57-2)

  • Risk Assessment

    A systematic process of organizing information to support a risk decision to be made within a risk management process. It consists of identification of hazards and the analysis and evaluation of risk associated with exposure to those hazards. (TR30) (TR44) (TR54) (TR58) (TR55) (TR67) (TR57-2) (TR54-5)

  • Secondary (Working, In-house) Reference Standard

    Substance of established quality and purity that is qualified against, and used instead of, the primary reference standard; typically used as a reference standard for routine laboratory analysis. (TR57-2)

  • Sensitivity

    Ability of a method to detect small changes in the quality attribute (e.g., changes in concentration or purity) being measured. (TR57-2)

  • Stress Studies (Degradation Pathway Studies)

    Studies undertaken to elucidate the intrinsic stability of the drug substance and/or drug product; part of the development strategy and normally carried out under more severe conditions (e.g., high or low pH or oxidation levels, or shaking) than those used for accelerated testing. (TR57-2)

  • Target Criteria

    Numerical limits, ranges, or other suitable measures of target performance levels of an analytical method that indicate suitable performance for intended use. For a method entering qualification, this is a target performance criterion that, when assessed, indicates that the method is qualified for its intended purpose. (TR57-2)

  • Two One-Sided T-Test

    A method for declaring the comparability of equivalence that is built around comparing two or more group means and their respective mean difference confidence intervals against predetermined equivalence limits. (TR57-2)