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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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)
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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)
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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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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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Dwell Time
The period that items are subjected to a given processing condition. [Synonym: Residence Time] (TR3)
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Endotoxin Indicator (EI) for Depyrogenation
An article challenged with a vial of endotoxin (or a carrier spiked with endotoxin) designed for use in depyrogenation studies. The endotoxin (a purified lipopolysaccaride) is validated for use in or on an endotoxin indicator. The carrier is made from a material appropriate for the intended depyrogenation processes to which it will be subjected. The endotoxin on a carrier is added at a concentration sufficient to allow recovery of a minimum of 1000 USP endotoxin units/carrier. The endotoxin indicator would allow for accurate indication of at least a 3-log reduction in USP endotoxin units during depyrogenation process challenges. (TR3)
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F-Value (Lethality Factor)
A measurement of sterilization effectiveness, the F-value is the calculated equivalent lethality (using a specified z-value), in terms of minutes at a reference temperature (Tref), delivered by a sterilization cycle. (TR1) (TR3) (TR30) (TR48) (TR61)
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F-Value (Lethality Factor)-- FH
A term used when the specific reference conditions of Tref = 160°C and z=20°C are used to calculate the equivalent lethality. For example, when the z-value of the BI is 20°C a process with an F(T=160°C, z=20°C), or FH, equal to 8 minutes is equivalent (in terms of delivered lethality) to a square wave process of 8 minutes at 160°C. A square wave process that provided an exposure of 45.2 minutes at 145°C would also yield an FH of 8 minutes. (TR3)
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Heat-up Phase
The phase of a sterilization cycle that occurs prior to the exposure phase. Process parameters are developed for this phase in order to meet applicable user requirements for load conditioning (e.g., air removal and preheating.) (TR01) (TR3) (TR48) (TR61)
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Leak Rate
Leak rate is the quantity of air leakage over time into the sterilizer chamber obtained while performing a chamber leak test. The leak rate should not exceed a level that will inhibit the sterilization process during air removal or vacuum drying stages. (TR03)
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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)
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Load Zone
Area within the sterilization chamber where materials to be sterilized may be placed. (TR01) (TR3) (TR48)
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Maximum Load
The maximum quantity or mass of items permitted in a sterilizer load. (TR01) The maximum quantity or mass of items permitted in a depyrogenation or sterilization load. (TR3) The maximum quantity or mass of products permitted in a validated sterilizer load. (TR30)The maximum quantity or mass of items permitted in a sterilizer load. (TR48)
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Overkill Design Approach
A sterilization design approach where minimal information is required about the product bioburden. A worst-case bioburden assumption is used to determine the delivered lethality needed to achieve a PNSU of 10-6 on or in the items being sterilized. When using this approach, the qualification program must demonstrate that both the FBIO and FPHYS are greater than 12 minutes. The required lethality may vary regionally. (Note: For typical SIP systems, the FPHYS will need to be greater than the FBIO.) (TR01) (TR3) (TR30) (TR61)
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Parametric Release
A sterility release system based upon effective control, monitoring, documentation, and batch records review of a validated sterilization process cycle in lieu of release procedures based upon end-product sterility testing. (TR01) (TR3) (TR13) A sterility release program based on effective control, monitoring and documentation of a validated sterile-product manufacturing process where sterility release is based on demonstrated achievement of critical operational parameters and performance attributes in lieu of end-product sterility testing. (TR30)
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Penetration Probe
A probe placed in contact with the load item or inside a container of liquid to measure the temperature of the load item or liquid. (TR01) A thermocouple placed in contact with the load item to measure the temperature of the load item. (TR3)
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Physical Qualification
A component of performance qualification that demonstrates that predetermined physical requirements, including temperature distribution and heat penetration, are achieved consistently throughout the load. (TR01)(TR03)
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Pyrogen
Any substance capable of eliciting a febrile (or fever) response upon injection or infection (as in endotoxin released in vivo by Gram-negative bacteria. (TR3) Fever-producing substance (TR69) A material that elicits a pyrogenic response (fever). (TR70)
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Sterilization Cycle
A sequence of defined operating parameters (e.g., time, temperature and pressure) and conditions required to render an item sterile. (TR01) (TR30) (TR48) A sequence of defined operating parameters (e.g., time and temperature) required to render an item sterile. (TR3)
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Sterilization Process
A process used to render a product free of viable organisms with a specified probability. (TR3)
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Temperature Distribution
Temperature measurement of the heating medium (e.g., forced hot air) across the chamber load zone. (TR01) (TR03) (TR30) (TR48)
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Thermocouple
A device for measuring temperature in which a pair of wires of different metals are joined and the free ends of the wires are connected to an instrument (such as a voltmeter) that measures the electrical potential difference created at the junction of the two metals. (TR3)
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Thermometric Study
The utilization of independent temperature monitoring devices to determine a temperature profile within the load zone and analysis of the collected data. (TR3)
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Water for Bacterial Endotoxin Test (BET)
Sterile Water for Injection or other water that shows no reaction with the specific bacterial endotoxin test reagent with which it is to be used, at the limit of sensitivity of such reagent. (TR3)
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Worst Case Load
The load configuration that is determined to be most difficult to sterilize. This is a function of the cycle control strategy and load item characteristics (e.g., mass, configuration, or air removal challenges). For porous/hard goods loads, this may not necessarily be the minimum or maximum load. (TR01) The load configuration that is determined to be most difficult to sterilize or depyrogenate. This is a function of the process control strategy and load item characteristics (e.g., mass, configuration). (TR3)
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Z-Value
The number of degrees of temperature change necessary to change the D-value by a factor of 10. The z-value allows integration of the lethal effects of heat as the temperature changes during the heating and cooling phases of a sterilization cycle. (TR01) (TR3) The number of degrees of temperature change necessary to change the D-value by a factor of 10. The z-value allows integration of the lethal effects of heat over time (i.e., calculation of F0) as the temperature changes in a cycle. (TR61)