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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 #

  • Activity

    Ability of endotoxin (LPS) to initiate the LAL cascade in the compendial bacterial endotoxins test (BET) assay, or the ability to elicit a pyrogenic response in a compendial pyrogen test (2,10). Activity can be measured by other assays such as the monocyte activation test (MAT) or recombinant Factor C tests (rFc), if such tests have been validated, to demonstrate that decisions made from the results are comparable to or superior to the compendial assay. Activity is measured in endotoxin units (EU). In terms of activity, one EU = one IU, regardless of the source. Activity is generally expressed as a concentration, usually EU/mL.(TR82)

  • Control Standard Endotoxin (CSE)

    Endotoxin preparations other than the international or national reference standards that are traceable in their calibration to the international endotoxin reference standard. A CSE is a secondary or tertiary standard, commonly purified from Escherichia coli, and is usually manufactured and certified by an LAL reagent manufacturer for use with a specific lot of reagent under defined assay conditions.(TR82)

  • Exotoxin

    Lipopolysaccharides from the cell walls of bacteria, the most potent of which derive from Gram-negative organisms. When injected, they are known to cause a febrile, or fever-producing reaction that can cause severe patient reactions, and on occasion, can be fatal. (TR26) (TR44)

    Pyrogenic lipopolysaccharide component of Gram-negative bacterial cell walls.(TR69)

    The major constituent of the outer membrane of Gram-negative bacteria is composed of lipid A, the core polysaccharide, and the O-antigen polysaccharide; endotoxin is also known as lipopolysaccharide (LPS).(TR82)

  • Lipopolysaccharide

    A component of the cell wall of Gram-negative bacteria.(TR3)

    Component of the outer cell wall of Gram-negative bacteria that is pyrogenic. (TR69)(TR82)

  • Low Endotoxin Recovery (LER)

    The inability to recover ≥50% activity over time when known amount of endotoxin is added to an undiluted product. LER cannot be overcome by dilution.(TR82)

  • Masking

    A type of interference that may result in low endotoxin recovery.(TR82)

  • Measured Values

    Those values where activity is confirmed by interpolation from a reference standard curve.(TR82)

  • Naturally Occurring Endotoxin (NOE)

    Endotoxin prepared from Gram-negative bacteria produced under defined conditions and with minimal nonchemical processing, e.g., centrifugation and filtration.(TR82)

  • Nominal Value

    The assumed activity of an endotoxin preparation, dilution, or "spike"; based on label-claim information.(TR82)

  • Potency

    The measure of the biological activity using a suitably quantitative biological assay, based on the attribute of the product that is linked to the relevant biological properties. (TR57)

    An expression of the activity of a secondary calibration standard to relate units of weight (ng/ vial or ng/mL) to units of activity (EU/ng) in a preparation.(TR82)

  • Reference Standard Endotoxin (RSE)

    The primary standard from USP, EDQM, JP and WHO for use in the harmonized compendial bacterial endotoxins test (BET). The current 3rd International Standard (WHO), USP, and EDQM RS are lyophilized formulation that contains highly purified LPS that is chemically extracted and purified from E. coli strain O113:H10:K(-) and further formulated with stabilizers and excipients.(TR82)