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Glossary of Terms - D

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D5W (5 D/W)
One of the most prevalent of LVPs (also see: LVP (Large Volume Parenteral)). Five percent dextrose in water. Presence of dextrose presents significant filtration problems. Usually requires activated charcoal pretreatment.

Dalton
The unit of molecular weight, equal to the weight of a hydrogen atom.

Data Integrity
The validity of data and their relationships. For electronic records to be trustworthy and reliable, the links between raw data, metadata, and results must not be compromised or broken. Without data integrity, it is not possible to regenerate a previous result reliably.

Data Migration
The process of translating data from one system to another when a company replaces the current computing systems with a new one. CFR 21 Part 11 mandates that data migration implementation create accurate and complete copies of the records when they are moved to a new system.

DDC (Direct Digital Control)
A collection of control units (analog and discrete) connected into a data highway, usually with a host or alarming/recording computer attached.

D Value
The time under a stated set of exposure conditions (temperature in an autoclave) required to reduce a microbial population by a factor of 90% (e.g. from 10,000 to 1,000).

Dead Leg
An area of entrapment in a vessel or piping run that could lead to contamination of the product. In a piping system, a non-flowing pocket, tee, or extension from a primary piping run that exceeds a defined number of pipe diameters from the ID of the primary pipe. Denoted by the term L/D or L/A, where L is equal to the leg extension perpendicular to the normal flow pattern or direction, A is the annular gap width, and D is equal to the ID (or inside dimension) of the extension or leg. In some existing standards, the dimension L is measured from the centerline of the primary pipe. For bioprocessing systems, an L/D of 2:1 is achievable with today's component technology for most valving and piping configurations.

Decontamination
A process that reduces contaminating substances to a defined acceptance level.

Deflagration
An exothermic reaction, such as the extremely rapid oxidation of a combustible dust or flammable vapor in air, in which the reaction progresses through the unburned material at a rate less than the velocity of sound. A deflagration can have an explosive effect.

Degrading
Deterioration of a surface finish so that pieces of the finish (or substrate) material large enough to be visible to the unaided eye, dislodge without any direct physical contact and fall from the surface of the material.

Deionization
Removing dissolved ions from solution by passing the solution through a bed of ion exchange resin, consisting of polymer beads that exchange hydrogen ions for cations and hydroxyl ions for anions in solution. The ionic impurities remain bound to the resins and the hydrogen and hydroxyl ions combine with each other to form water.

Deletion Map
A description of a specific chromosome that uses defined mutations - specific deleted areas in the genome - as "biochemical signposts", or markers for specific areas.

De Minimis Release
The release of viable microbiological agents or eukaryotic cells that does not result in the establishment of disease in healthy people, plants, or animals; or in uncontrolled proliferation of any microbiological agents or eukaryotic cells.

Dementia
Severe impairment of mental functioning.

Demineralization
Sometimes used interchangeably with deionization, it refers to the removal of minerals and mineral salts using ion exchange. Water softening is a common form of demineralization.

Denaturation
The loss of the native structure of a macromolecule resulting, from heat treatment, extreme pH changes, chemical treatment, etc. It is accompanied by loss of biological activity. For example, proteins may be denatured by heat, pH extremes, or addition of agents such as urea or guanidinium hydrochloride.

Dent
A typical stainless steel interior surface anomaly that refers to a large, smooth-bottomed depression whose diameter or width is greater than its depth and which will not produce an indication.

Deoxyribonucleotide


Depyrogenation
The removal or destruction of endotoxins.

Desalination
The removal of dissolved salts from brine to produce potable water.

Design Condition
The specified range or accuracy of a controlled variable used by the designer to determine performance requirements of an engineered system.

Design Specification
A specification that defines the design of a system or system component.

Desiccant
Chemical salt used to dehumidify air, to control moisture in materials contacting that air.

Desiccators
Closed containers, usually made of glass or plastic, with an airtight seal used for drying materials.

Detonation
An exothermic reaction characterized by the presence of a shock wave in a material that establishes and maintains the reaction. The reaction zone progresses through the material at a rate greater than the velocity of sound. The principal heating mechanism is one of shock compression. Detonations have an explosive effect.

Deuteromycetes
Molds that cannot reproduce by sexual means. Some pathogenic fungi such as Trichophyton, which causes athlete's foot, belong to this family.

DHL Vaccine
A tri-valent vaccine. Also, the most common veterinary vaccine that has a combination of viral and bacterial vaccines. Used for distemper, hepatitis (canine), and leptospira.

Diagnostic
A substance or group of substances used to identify a disease by analyzing the cause and symptoms.

Dialysis
The separation of low-molecular weight compounds from high molecular weight components by diffusion through a semipermeable membrane. Frequently utilized to remove salts, introduce salts, remove biological effectors such as nicotinamide adenine dinucleotides, nucleotides phosphates, etc. from polymeric molecules such as protein, DNA, RNA, etc. Commonly used membranes have a molecular weight cutoff around 10,000 but other membrane pore sizes are available.

Diatom
Any minute, unicellular or colonial algae of the class Bacillariophyceae having siliceous cells walls consisting of two overlapping symmetrical parts.

Diatomaceous Earth, Diatomite, Kiselguhr (DE)
Fine silicaceous powder used as a filter aid.

Diffusion
The random thermal motion of particles, which causes them to flow from a region of higher concentration to one of lower concentration until they are uniformly distributed.

Digestion
The enzymatic hydrolysis of major nutrients in the gastrointestinal system to yield their building-block components.

Digital
A series of on and off pulses arranged to convey information.

Digital Certificate
An attachment to an electronic message used for security purposes. The most common use of a digital certificate is to verify that a user sending a message is who he or she claims to be and to provide the receiver with the means to encode a reply.

Digital Representation
Biometric parameters such as a fingerprint or retinal pattern are turned into data that a computer understands: the digital representation of the biometric. The pattern in the biometric divides it into a grid of boxes, and a zero or a one, depending on whether the box is filled in, marks each box.

Digital Signature
An electronic signature based upon cryptographic methods of originator authentication, computed by using a set of rules and a set of parameters such that the identity of the signer and the integrity of the data can be verified.

Dilution
Lowering the concentration of a solution by adding more solvent.

Dilution Factor
The ratio of solvent to solute by volume.

Diploid
A full set of genetic material, consisting of paired chromosomes one chromosome from each parental set. Most animal cells except the gametes have a diploid set of chromosomes. The diploid human genome has 46 chromosomes.

Diplophase
A phase in the life cycle of an organism where the organism has two copies of each gene. The organism is said to be diploid.

Direct Impact System
An engineering system that may have a direct impact on product quality.

Disaster
Any event (i.e. fire, earthquake, power failure etc.), which could have a detrimental effect upon an automated system or its associated information.

Discoloration (welding)
Any change in surface color from that of the base metal. Usually associated with oxidation occurring on the weld and heat affected zone (HAZ) on the outside diameter and inside diameter of the weld joint as a result of heating the metal during the welding. Colors may range from pale bluish-gray to deep blue, and from pale straw color to a black crusty coating.

Disinfection
Process by which viable microbiological agents or eukaryotic cells are reduced to a level unlikely to produce disease in healthy people, plants, or animals. These processes may use chemical agents, heat, ultraviolet light, etc. to destroy most (but not necessarily all) of the harmful or objectionable microorganisms, pathogens, and potential pathogens. Disinfection does not necessarily result in sterilization.

1. "High level disinfection" inactivates fungi, viruses, and bacteria. High-level chemical disinfectants maybe ineffective against bacterial spores if they are present in large numbers. Extended exposure times may be required.
2. "Intermediate level disinfection" destroys fungi, some viruses (lipid and most non-lipid medium-size and small viruses), mycobacteria, and bacteria.
3. "Low level disinfection" kills vegetative forms of bacteria, some fungi, and some medium-size and lipid-containing viruses. Low-level disinfectants do not reliably kill bacterial spores, mycobacteria, or small or non-lipid viruses.

Dispensing
The pouring or transferring of any material from a container, tank or similar vessel, whereby vapors, dusts, fumes, mists or gases may be liberated to the atmosphere.

Dissimilation
The breakdown of food material to yield energy and building blocks for cellular synthesis.

Dissolved Solids
The amount of nonvolatile matter dissolved in a water sample, usually expressed in parts per million (PPM) by weight.

Distillation
The process of separating water from impurities by heating until it changes into vapor and then cooling the vapor to condense it into purified water.

DNA (Deoxyribonucleic Acid)
The molecule of which the genetic material is composed. It consists of two chains joined together as a double helix. Each chain is composed of a polymer of nucleotides (consisting of a nitrogenous base, a deoxyribosesugar ring, and a phosphate group) joined together by phosphodiester bonds between the 5'-phosphate of one nucleotide and the 3'-hydroxyl of the next. The two chains run in opposite directions and are held together by hydrogen bonds between the bases in equivalent positions in the two chains. There are various forms of double helical DNA. They are:
1. B-DNA (first described by Crick and Watson) is a right-handed helix with 10.6 base pairs per turn and is probably the main form of cellular DNA.
2. A-DNA is also a right-handed helix but is somewhat skewed and contains about 11 base pairs per turn. It is the form taken By DNA-RNA hybrid double helixes.
3. Z-DNA is a left-handed helix with 11 base pairs per turn. It is favored by regions rich in guanine cutosine base pairs and probably occurs infrequently in cellular DNA.

DNA (Deoxyribonucleic Acid)
The molecular basis for genes; every inherited characteristic has its origin somewhere in the code of the organism's complement of DNA. The code is made up of subunits, nucleic acids. The organism to produce the required proteins that compose the genetic traits of the organism and its life functions interprets the sequence of the four nucleic acids.

DNAse (Deoxyribonuclease)
An enzyme that degrades DNA.

DNA Array
Spots of DNA arranged on a slide support such as glass or silicon "DNA chip" (or microarray), used for screening, sequencing, genetic mapping, and so on.

DNA Replication
The use of existing DNA as a template for the synthesis of new DNA strands. In humans and other eukaryotes, replication occurs in the cell nucleus.

DNA Sequence
The relative order of base pairs, whether in a fragment of DNA, a gene, a chromosome, or an entire genome. (also see:

DNA Vector
A DNA vehicle for transferring generic information from one cell to another.
Documentation Written or pictorial information describing, defining, specifying, and/or reporting of certifying activities, requirements, procedures or results.

Domain
A discrete portion of a protein with its own function. The combination of domains in a single protein determines its overall function.

Dominant Allele
A gene that is expressed, regardless of whether its counterpart allele on the other chromosome is dominant or recessive. Autosomal dominant disorders are produced by a single mutated dominant allele, even though its corresponding allele is normal.

DOP (Dioctyl Phthalate)
A mono-dispersed test aerosol of sub-micron particles, generated to challenge (evaluate integrity) of HEPA filters for HVAC.

DOP (Dispersed Oil Particulate)
(also see: DOP (Dioctyl Phthalate))

Dosage Form
The form in which the drug is delivered to the patient. This could be parenteral, topical, tablet, oral (liquid or dissolved powder), suppository, inhalation, transdermal, etc.

Dosage Group
A group of subjects in a clinical trial receiving the same dosage (amount) of a drug being tested.

Double Blind Test
Used in Clinical Trials, this is a method to ensure that any one party cannot improperly influence the test. The product (either in a single strength dosage or in multiple dosages) and the placebo are packaged and given a code name known to only the initiating party. These are then sent to another party who gives the coded packages yet another code name or number, and makes a matrix of the previous name/number to the new name/number. This is then sent to the physician who administers these to the patient. At the end of the test, the physician provides records of which patient received which code name/number product. This is then cross-referenced to the intermediate matrix to determine the original code name/number. The results of the treatment are then correlated to determine the efficacy of the drug.

The structure of DNA as proposed by Watson and Crick. It consists of two right-handed helical polynucleotide chains coiled around the same axis. The two chains are anti-parallel with their 3rd to 5th internucleotide phosphodiester bonds running in opposite directions. Under most conditions, the coiling of the chains is such that if the ends are held still, as in circular DNA or in a large chromosome, the chains cannot be separated except by cleavage of one of the strands.

Drugs 
Articles intended for use in diagnosis, cure, mitigation, treatment, or prevention of disease in man or other animals" and "articles (other than food) intended to affect the structure or any function of the body of man or other animals.

Drug Product
A finished dosage form, for example, tablet, capsule, solution, etc., that contains one or more APIs (Active Pharmaceutical Ingredients) generally, but not necessarily, in association with inactive ingredients. The term also includes a finished dosage form, which does not contain an API but is intended to be used as a placebo.

Drug (Medicinal) Product
The dosage form in the final immediate packaging intended for marketing.

Durability
The ability to withstand the rigors of the environment without degrading or requiring repair.

Dry Air
Air from which all water vapor and contaminants have been removed. Its composition by volume is:
1. Nitrogen 78.08%
2. Oxygen 20.95%
3. Argon 0.93%
4. Carbon Dioxide 0.03
5. Other gases 0.00003

Dry Heat Sterilization
Sterilization utilizing a heating oven or continuous tunnel (gas or electric heated), as opposed to steam sterilization in an autoclave, usually used for glassware and metal parts. In depyrogenation temperatures of 250ºC result in sterilization and the inactivation of endotoxin present on the surface of the equipment.

Dust (also see: Combustible Dust)
Dusting Deterioration of the finish at the surface so it is easily loosened from the surface by light physical contact (such as wiping one's hand across the surface), mechanically induced air movements or naturally occurring air movements.

Dynamic Conditions
Environmental conditions of a manufacturing room occupied by the normal number of workers appropriately garbed and with production equipment in operation. However, dynamic conditions for some dusty operations, such as aseptic powder filling, may be measured in the absence of product.

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Pharmaceutical Abbreviations | Abbreviations in product information leaflets and literature
Acronyms | Glossary of Terms | Abbreviations used in the British Pharmaceutical