Drug reaction testing
Encyclopedia
Drug reaction testing uses a genetic test to predict how a particular person will respond to various prescription and non-prescription medication
s. It checks for genes that code for specific liver
enzyme
s which activate, deactivate, or are influenced by various drugs.
There are currently four genetic marker
s commonly tested for: 2D6
, 2C9
, 2C19
, and 1A2
.
This testing has been done for some time by drug companies working on new drugs, but is relatively newly available to the general public. Strattera is the first drug to mention the test in the official documentation, although it doesn't specifically recommend that patients get the test before taking the medication.
There are four possible categories for each marker: poor metabolizer, intermediate metabolizer, extensive metabolizer, or ultra-extensive metabolizer. Different testing companies may call these by different names. Extensive metabolizers (that is, people who are extensive metabolizers of a given type) are the most common, and are the type of people for which drugs are designed. Up to 7% of Caucasians are poor metabolizers of drugs metabolized by the CYP
2D6 enzyme.
People who can't metabolize
a drug will require a much lower dose than is recommended by the manufacturer, and those who metabolize it quickly may require a higher dose. Some drugs, such as codeine
, will not be effective in people without the requisite enzymes to activate them.
People who are poor metabolizers of a drug may overdose while taking less than the recommended dose.
Medication
A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...
s. It checks for genes that code for specific liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s which activate, deactivate, or are influenced by various drugs.
There are currently four genetic marker
Genetic marker
A genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify cells, individuals or species. It can be described as a variation that can be observed...
s commonly tested for: 2D6
CYP2D6
Cytochrome P450 2D6 , a member of the cytochrome P450 mixed-function oxidase system, is one of the most important enzymes involved in the metabolism of xenobiotics in the body. Also, many substances are bioactivated by CYP2D6 to form their active compounds...
, 2C9
CYP2C9
Cytochrome P450 2C9 is a protein that in humans is encoded by the CYP2C9 gene.- Function :CYP2C9 is an important cytochrome P450 enzyme with a major role in the oxidation of both xenobiotic and endogenous compounds. CYP2C9 makes up about 18% of the cytochrome P450 protein in liver microsomes...
, 2C19
CYP2C19
Cytochrome P450 2C19 , a member of the cytochrome P450 mixed-function oxidase system, is involved in the metabolism of xenobiotics in the body. It is involved in the metabolism of several...
, and 1A2
CYP1A2
Cytochrome P450 1A2 , a member of the cytochrome P450 mixed-function oxidase system, is involved in the metabolism of xenobiotics in the body...
.
This testing has been done for some time by drug companies working on new drugs, but is relatively newly available to the general public. Strattera is the first drug to mention the test in the official documentation, although it doesn't specifically recommend that patients get the test before taking the medication.
There are four possible categories for each marker: poor metabolizer, intermediate metabolizer, extensive metabolizer, or ultra-extensive metabolizer. Different testing companies may call these by different names. Extensive metabolizers (that is, people who are extensive metabolizers of a given type) are the most common, and are the type of people for which drugs are designed. Up to 7% of Caucasians are poor metabolizers of drugs metabolized by the CYP
CYP
CYP is a three-letter abbreviation which may refer to:* CINOP Young Professionals* Calbayog, in the Philippines * Crystal Palace railway station, the national railway code for a railway station in London, UK* Cape York Peninsula, Australia...
2D6 enzyme.
People who can't metabolize
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
a drug will require a much lower dose than is recommended by the manufacturer, and those who metabolize it quickly may require a higher dose. Some drugs, such as codeine
Codeine
Codeine or 3-methylmorphine is an opiate used for its analgesic, antitussive, and antidiarrheal properties...
, will not be effective in people without the requisite enzymes to activate them.
People who are poor metabolizers of a drug may overdose while taking less than the recommended dose.
See also
- Medical prescriptionMedical prescriptionA prescription is a health-care program implemented by a physician or other medical practitioner in the form of instructions that govern the plan of care for an individual patient. Prescriptions may include orders to be performed by a patient, caretaker, nurse, pharmacist or other therapist....
- ContraindicationContraindicationIn medicine, a contraindication is a condition or factor that serves as a reason to withhold a certain medical treatment.Some contraindications are absolute, meaning that there are no reasonable circumstances for undertaking a course of action...
- Cytochrome P450
- Drug metabolismDrug metabolismDrug metabolism is the biochemical modification of pharmaceutical substances by living organisms, usually through specialized enzymatic systems. This is a form of xenobiotic metabolism. Drug metabolism often converts lipophilic chemical compounds into more readily excreted polar products...