
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.
(Please select "All" to restart a filtered Search)
Refine Results
Filter By Technical Report Number
- TR 75: Mycoplasma Filter Rating Method (8)
- TR 22: Aseptic Process Simulation (6)
- TR 45: Depth Filtration (6)
- TR 62: Manual Aseptic Processes (5)
- TR 26: Sterilizing Filtration of Liquids (5)
- TR 69: Bioburden/Biofilm Management (4)
- TR 41: Virus Filtration (4)
- TR 15: Validation: TFF in Biopharmaceuticals (3)
- TR 50: Alt. Methods Mycoplasma Testing (2)
- TR 60: Process Validation (2)
- TR 70: Cleaning/Disinfection Programs (2)
- TR 13: Environmental Monitoring (2)
- TR 14: Validation: Protein Purification Chromatography (2)
- TR 28: Process Simulation for Bulk API (2)
- TR 47: Virus Spikes/Virus Clearance (1)
- TR 51: Biological Indicators (1)
- TR 55: TBA/TCA Detection Mitigation (1)
- TR 61: Steam in Place (1)
- TR 67: Objectionable Microorganisms (1)
- TR 74: Reprocessing of Biopharmaceuticals (1)
- TR 1: Validation: Moist Heat (1)
- TR 88: Microbial Data Deviation Investigations in the Pharmaceutical Industry (1)
- TR 77: The Manufacture of Sterile Pharmaceutical Products Using Blow-Fill-Seal Technology (1)
- TR 42: Validation: Protein Manufacturing (1)
Filter By Technical Report Keyword
Filter By Technical Report Category
Acholeplasma laidlawii
A. laidlawii is a mycoplasma in class Mollicutes and order Acholeplasmatales. (TR75)
Source:
Action Level (environmental monitoring)
An established microbial or non-viable particle level that, when exceeded, should trigger appropriate investigation and corrective action based on the investigation. (TR22)
Source:
Action Limit
An internal (in-house) value used to assess the consistency of the process. The cause of the excursion should be investigated and documented and corrective action is generally required. Action limits are not specifications. (TR42)
An established internal (in-house) data-based value which is part of the control strategy and used to assess the consistency of the manufacturing process. An action limit excursion result in an investigation, identification of recovered isolates, root-cause analysis, assessment of a systemic failure and impact on product quality and patient safety. (TR69)
An established internal (in-house) data-based value that is part of the control strategy and used to assess the consistency of the manufacturing process. An action limit excursion result in an investigation, identification of recovered isolates, root-cause analysis, assessment of a systemic failure and impact on product quality and patient safety. (TR74)
A limit that, when exceeded, indicates a process is outside of its normal operating range. A response to such an excursion should involve a documented investigation and corrective actions based on the results of that investigation. (TR60)
Source:
Aerobic Microorganism
A microorganism that utilizes oxygen as the final electron acceptor during metabolism; a microorganism that will grow primarily in the presence of oxygen. For the purpose of this report, this definition encompasses facultative anaerobes. (TR22) (TR62)
Source:
Alert Level
An established microbial or nonviable particle level giving early warning of potential drift from normal operating conditions; not necessarily grounds for definitive corrective action but typically requires follow-up investigation. (TR13) (TR22) (TR69)
An established level that, when exceeded, is giving an early warning of a potential drift from normal operating conditions; while not necessarily grounds for definitive corrective action, it typically requires follow-up review. (TR 60)
An established microbial or nonviable particle level giving early warning of potential drift from normal operating conditions; not necessarily grounds for definitive corrective action, but typically requires follow-up investigation (3, 4, 7). (TR88)
Source:
Anaerobic Microorganism
A microorganism that does not utilize oxygen as the final electron acceptor during metabolism; microorganism that will grow only in the absence of oxygen. (TR62)(TR22)
Source:
Aseptic Processing
Handling sterile materials in a controlled environment, in which the air supply, facility, materials, equipment and personnel are regulated to control microbial and particulate contamination to acceptable levels. (TR28) (TR62) (TR69) Handling of sterile product, containers, and/ or devices in a controlled environment in which the air supply, materials, equipment, and personnel are regulated to maintain (product) sterility. (TR13)
Source:
Aseptic Processing Area (APA)
Controlled environment, consisting of several zones, in which the air supply, facility, materials, equipment and personnel are regulated to control microbial and particulate contamination to acceptable levels. (TR22) (TR28) (TR62) (TR70)
Source:
Aseptic Processing Simulation (APS)
A means for establishing the capability of an aseptic process as performed using a growth medium. (TR22) (TR62)
Source:
Attachment (Adhesion)
Discrete association of a microorganism with an animate or inanimate surface. (TR69)
Source:
Back Pressure
Residual pressure opposing the free flow of liquid or gas at the outlet side of the filter. (TR45) Pressure applied downstream of a filter or other piece of equipment. (TR26)
Source:
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)
Source:
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)
Source:
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)
Source:
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)
Source:
Breakthrough Limited
A filtration operation resulting in a significant rise in filtrate turbidity accompanied by a small increase in differential pressure. This occurs when the adsorptive capacity of the filter is reached, resulting in the passage of particles smaller than the pore size of the filter that would normally be removed by adsorption. (TR45)
Source:
Brevundimonas Diminuta (B. diminuta)
Small bacteria (0.3–0.4 &mum in diameter by 0.6–0.1 &mum long) used to challenge a sterilizing grade filter during validation testing. [Formerly Pseudomonas diminuta](TR45)
Source:
Bubble Point Test
A test to indicate the maximum pore size of a filter. The differential gas pressure at which a liquid (usually water) is pushed out of the largest pores and a steady stream of gas bubbles is detected from a previously wetted filter under specific test conditions. Used to test filter integrity with specific, validated, pressure values, wetting liquids and temperatures for specific pore-size (and type of ) filters. (TR26)
Source:
Challenge Concentration
The concentration in Colony Forming Units/mL of the test microorganism in the challenge fluid. (TR75)
Source:
Challenge Level
The concentration of the test microorganism applied to the test filter (per centimeter squared) or the total number of cells applied to the test filter at the completion of the challenge. (TR75)
Source:
Challenge Volume
The volume of challenge fluid applied to the test filter. (TR75)
Source:
Column Load
The solute that is passed through the column for separation. (TR14)
Source:
Column Packing
Preparation of a column that includes the addition of resin slurry into a column to create a bed suitable for its intended use. Characteristics of a packed column bed include bed height and diameter, backpressure, and number of theoretical plates. (TR14)
Source:
Downstream Side (of Filter)
The effluent side of the process step (filter). (TR45) The filtrate or outlet side of the filter. (TR26)
Source:
Log Reduction
Log reduction is defined as the first log being 90%, the second log being 9% and the third log being 0.09% of the original inoculums. (TR70)
Source:
Mandrel
Specialized filling needles on certain BFS machines which also act to form the container. (TR77)
Source:
Media
The part of the filter through which fluid passes that retains particles during filtration. (TR45)
Source:
Microfiltration (MF)
Pressure-driven, membrane-based separation process in which particles and dissolved macromolecules (typically 0.1 &mum or larger) are retained. (TR15)
Source:
Mollicutes
A class of bacteria which lack a cell wall. Mollicutes are small, typically about 0.1-0.5 &mum in size, and vary in form (trivial name: mycoplasma) (TR50)
Source:
Most Probable Number (MPN) Method
A statistical method of estimating the number of viable organisms suspended in a liquid. (TR51)
Source:
Mycoplasma Reduction Filter
A sterilizing grade filter that also provides a log reduction value (or a titer reduction value) for a specified test mycoplasma according to the PDA Mycoplasma Consensus Method. (TR75)
Source:
Negative Control
A test article used to assess the performance of an assay in the known absence of a targeted microorganism or nucleic acid. Negative controls are used to minimize a risk of false positive results, which could occur due to non-specific signals. (TR50)
Source:
Nominal Molecular-Weight Cutoff (NMWCO)
A manufacturer’s measure of an ultrafiltration membrane based on a defined solute-retention coefficient. (TR15)
Source:
Nominal Pore Size Rating
A filter rating with an arbitrary value, indicating a particulate size range at which the filter manufacturer claims the filter removes some percentage. Nominal ratings vary from manufacturer to manufacturer and may not be suitable to compare filters among manufacturers. Processing conditions, such as operating pressure and concentration of contaminant may have a significant effect on the retention efficiency of the nominally rated filters. (TR41)
Source:
Nonspecific Model Virus
A virus used for characterization of viral clearance of the process when the purpose is to characterize the capacity of the manufacturing process to remove and/or inactivate viruses in general (i.e., to characterize the general viral clearance capacity of the purification process.) (TR41)
Source:
Positive Control Filter Membrane (Penetration Control)
A control filter membrane with a larger pore size rating than the test filter and used to demonstrate the penetrative ability of the test microorganism. Penetration of this filter by at least one CFU is required to validate a test. (TR75)
Source:
Psid
Pound-force per square-inch differential is the difference in pressure; for example, the pressure differential between the upstream (influent) and downstream (effluent) sides of a filter. (TR75)
Source:
Screening Studies
Studies used to select a particular type and grade of filter media. (TR45)
Source:
Titer Reduction (TR)
A measure of the degree to which a particular filter removes a microorganism under specified test conditions. Calculated as the ratio of the total number of microorganisms used to challenge the filter divided by the total number of microorganisms that passed through the filter. (TR75)
Source:
Upstream
The influent side of the filter. (TR45) (TR26)
Source:
Water Activity (Aw)
Water Activity, Aw is the ratio of the vapor pressure of water in a product (P) to the vapor pressure of water in a product (P) to the vapor pressure of pure water (Po) at the same temperature. It is numerically equal to 1/100 of the RH generated by the product in a closed system. It is a measure of the free or available moisture in the material. Note: Water activity ≠ water content. RH can be calculated from direct measurements partial vapor pressure or dew point, or from indirect measurements by sensors whose physical or electric characteristics are altered by the RH to which they are exposed. Microorganisms need available water within a pharmaceutical product, as well as nutrients and minerals, to proliferate. Water activity, and not water content, is a better measure of the free water, in contrast to bound water that microbial cells require for metabolic activity and osmotic regulation. Effects of reduced Aw on microbial growth include a longer lag phase, slower growth rate, lower numbers of organisms in the stationary phase, and reduced microbial toxin production; below a specified Aw for an organism, microbial growth will not occur. (TR55) (TR67)