The Anatomical Therapeutic Chemical (ATC) Classification System is used for the classification of active ingredients of drugs according to the organ or system on which they act and their therapeutic, pharmacological and chemical properties. It is controlled by the World Health Organization Collaborating Centre for Drug Statistics Methodology (WHOCC), and was first published in 1976.
Contents
- History
- Classification
- First level
- Second level
- Third level
- Fourth level
- Fifth level
- ATCvet
- Defined daily dose
- Adaptations and updates
- References
This pharmaceutical coding system divides drugs into different groups according to the organ or system on which they act and/or their therapeutic and chemical characteristics. 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: acetylsalicylic acid (aspirin), for example, has A01AD05 (WHO) as a drug for local oral treatment, B01AC06 (WHO) as a platelet inhibitor, and N02BA01 (WHO) as an analgesic and antipyretic. On the other hand, several different brands share the same code if they have the same active substance and indications.
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 (EphMRA) and is being maintained by the EphMRA and the Pharmaceutical Business Intelligence and Research Group (PBIRG). 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
Second level
The second level of the code indicates the therapeutic main group and consists of two digits.
Example: C03 Diuretics
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 Sulfonamides
Fifth level
The fifth level of the code indicates the chemical substance and consists of two digits.
Example: C03CA01 Furosemide
ATCvet
The Anatomical Therapeutic Chemical Classification System for veterinary medicinal products (ATCvet) is used to classify veterinary 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.
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, "[t]he 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 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. In order to create a new ATC code, an application has to be sent to the WHO. New ATC codes are published twice annually. A formal release of new ATC edition occurs once a year.