The Anatomical Therapeutic Chemical (ATC) Classification System is a drug classification system that classifies the

active ingredient An active ingredient is any ingredient that provides biologically active or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease or to affect the structure or any function of the body of humans or animals. The ...

s of

drug A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via inhala ...

s according to the

organ Organ may refer to: Biology * Organ (biology), a part of an organism Musical instruments * Organ (music), a family of keyboard musical instruments characterized by sustained tone ** Electronic organ, an electronic keyboard instrument ** Hammond ...

system A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and express ...

on which they act and their

therapeutic A therapy or medical treatment (often abbreviated tx, Tx, or Tx) is the attempted remediation of a health problem, usually following a medical diagnosis. As a rule, each therapy has indications and contraindications. There are many different ...

pharmacological Pharmacology is a branch of medicine, biology and pharmaceutical sciences concerned with drug or medication action, where a drug may be defined as any artificial, natural, or endogenous (from within the body) molecule which exerts a biochemica ...

and chemical properties. Its purpose is an aid to monitor drug use and for

research Research is "creative and systematic work undertaken to increase the stock of knowledge". It involves the collection, organization and analysis of evidence to increase understanding of a topic, characterized by a particular attentiveness ...

to improve quality medication use. It does not imply drug recommendation or

efficacy Efficacy is the ability to perform a task to a satisfactory or expected degree. The word comes from the same roots as ''effectiveness'', and it has often been used synonymously, although in pharmacology a distinction is now often made between ...

. It is controlled by the

World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level o ...

Collaborating Centre for Drug Statistics Methodology (WHOCC), and was first published in 1976.

Coding system

This pharmaceutical coding system divides drugs into different groups according to the organ or system on which they act, their

intent or nature, and the drug's chemical characteristics. Different brands share the same code if they have the same active substance and indications. Each bottom-level ATC code stands for a pharmaceutically used substance, or a combination of substances, in a single indication (or use). This means that one drug can have more than one code, for example

acetylsalicylic acid Aspirin, also known as acetylsalicylic acid (ASA), is a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and/or inflammation, and as an antithrombotic. Specific inflammatory conditions which aspirin is used to treat ...

(aspirin) has as a drug for local

oral The word oral may refer to: Relating to the mouth * Relating to the mouth, the first portion of the alimentary canal that primarily receives food and liquid ** Oral administration of medicines ** Oral examination (also known as an oral exam or or ...

treatment, as a

platelet inhibitor An antiplatelet drug (antiaggregant), also known as a platelet agglutination inhibitor or platelet aggregation inhibitor, is a member of a class of pharmaceuticals that decrease platelet aggregation and inhibit thrombus formation. They are effectiv ...

, and as an

analgesic An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of drugs used to achieve relief from pain (that is, analgesia or pain management). It ...

and

antipyretic An antipyretic (, from ''anti-'' 'against' and ' 'feverish') is a substance that reduces fever. Antipyretics cause the hypothalamus to override a prostaglandin-induced increase in temperature. The body then works to lower the temperature, which r ...

; as well as one code can represent more than one active ingredient, for example is the combination of perindopril with amlodipine, two active ingredients that have their own codes ( and respectively) when prescribed alone. The ATC classification system is a strict hierarchy, meaning that each code necessarily has one and only one parent code, except for the 14 codes at the topmost level which have no parents. The codes are semantic identifiers, meaning they depict information by themselves beyond serving as identifiers (namely, the codes depict themselves the complete lineage of parenthood). As of 7 May 2020, there are 6,331 codes in ATC; the table below gives the count per level.

History

The ATC system is based on the earlier Anatomical Classification System, which is intended as a tool for the pharmaceutical industry to classify pharmaceutical products (as opposed to their active ingredients). This system, confusingly also called ATC, was initiated in 1971 by the

European Pharmaceutical Market Research Association European, or Europeans, or Europeneans, may refer to: In general * ''European'', an adjective referring to something of, from, or related to Europe ** Ethnic groups in Europe ** Demographics of Europe ** European cuisine, the cuisines of Europe a ...

(EphMRA) and is being maintained by the EphMRA and Intellus. Its codes are organised into four levels. The WHO's system, having five levels, is an extension and modification of the EphMRA's. It was first published in 1976.

Classification

In this system, drugs are classified into groups at five different levels:

First level

The first level of the code indicates the anatomical main group and consists of one letter. There are 14 main groups: ''Example'': C

Cardiovascular system The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...

Second level

The second level of the code indicates the therapeutic subgroup and consists of two digits. ''Example'': C03

Diuretic A diuretic () is any substance that promotes diuresis, the increased production of urine. This includes forced diuresis. A diuretic tablet is sometimes colloquially called a water tablet. There are several categories of diuretics. All diuretics i ...

Third level

The third level of the code indicates the therapeutic/pharmacological subgroup and consists of one letter. ''Example'': C03C High-ceiling diuretics

Fourth level

The fourth level of the code indicates the chemical/therapeutic/pharmacological subgroup and consists of one letter. ''Example'': C03CA

Sulfonamide In organic chemistry, the sulfonamide functional group (also spelled sulphonamide) is an organosulfur group with the structure . It consists of a sulfonyl group () connected to an amine group (). Relatively speaking this group is unreactive. ...

Fifth level

The fifth level of the code indicates the chemical substance and consists of two digits. ''Example'': C03CA01

furosemide Furosemide is a loop diuretic medication used to treat fluid build-up due to heart failure, liver scarring, or kidney disease. It may also be used for the treatment of high blood pressure. It can be taken by injection into a vein or by mo ...

Other ATC classification systems

ATCvet

The ''Anatomical Therapeutic Chemical Classification System for veterinary medicinal products'' (ATCvet) is used to classify

veterinary Veterinary medicine is the branch of medicine that deals with the prevention, management, diagnosis, and treatment of disease, disorder, and injury in animals. Along with this, it deals with animal rearing, husbandry, breeding, research on nutri ...

drugs. ATCvet codes can be created by placing the letter Q in front of the ATC code of most human medications. For example, furosemide for veterinary use has the code QC03CA01. Some codes are used exclusively for veterinary drugs, such as '' QI Immunologicals'', '' QJ51 Antibacterials for intramammary use'' or ''QN05AX90

amperozide Amperozide is an atypical antipsychotic of the diphenylbutylpiperazine class which acts as an antagonist at the 5-HT2A receptor. It does not block dopamine receptors as with most antipsychotic drugs, but does inhibit dopamine release, and alt ...

''.

Herbal ATC (HATC)

The Herbal ATC system (HATC) is an ATC classification of herbal substances; it differs from the regular ATC system by using 4 digits instead of 2 at the 5th level group. The herbal classification is not adopted by WHO. The Uppsala Monitoring Centre is responsible for the Herbal ATC classification, and it is part of the WHODrug Global portfolio available by

subscription The subscription business model is a business model in which a customer must pay a recurring price at regular intervals for access to a product or service. The model was pioneered by publishers of books and periodicals in the 17th century, a ...

Defined daily dose

The ATC system also includes defined daily doses (DDDs) for many drugs. This is a measurement of drug consumption based on the usual daily dose for a given drug. According to the definition, " e DDD is the assumed average maintenance dose per day for a drug used for its main indication in adults."

Adaptations and updates

National issues of the ATC classification, such as the

German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...

''Anatomisch-therapeutisch-chemische Klassifikation mit Tagesdosen'', may include additional codes and DDDs not present in the WHO version. ATC follows guidelines in creating new codes for newly approved drugs. An application is submitted to WHO for ATC classification and DDD assignment. A preliminary or temporary code is assigned and published on the website and in the ''WHO Drug Information'' for comment or objection. New ATC/DDD codes are discussed at the semi-annual Working Group meeting. If accepted it becomes a final decision and published semi-annually on the website and ''WHO Drug Information'' and implemented in the annual print/on-line ACT/DDD Index on January 1. Changes to existing ATC/DDD follow a similar process to become temporary codes and if accepted become a final decision as ATC/DDD alterations. ATC and DDD alterations are only valid and implemented in the coming annual updates; the original codes must continue until the end of the year. An updated version of the complete on-line/print ATC index with DDDs is published annually on January 1.

References

External links

* * Quarterly journal providing an overview of topics relating to medicines development and regulation. * from
EphMRA Anatomical Classification (ATC and NFC)

atcd
R script to scrape the ATC data from the WHOCC website; contains link to download entire ATC tree. {{portal bar , Medicine Drugs Pharmacological classification systems World Health Organization