Anatomical Therapeutic Chemical classification

The Anatomical Therapeutic Chemical (ATC) Classification System is used for the classification of drugs. It is controlled by the WHO Collaborating Centre for Drug Statistics Methodology, and was first published in 1976.

The classification system divides drugs into different groups according to the organ or system on which they act and/or their therapeutic and chemical characteristics.

Classification

In this system, drugs are classified into groups at 5 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:

Code	Contents
A	Alimentary tract and metabolism
B	Blood and blood forming organs
C	Cardiovascular system
D	Dermatologicals
G	Genito-urinary system and sex hormones
H	Systemic hormonal preparations, excluding sex hormones and insulins
J	Antiinfectives for systemic use
L	Antineoplastic and immunomodulating agents
M	Musculo-skeletal system
N	Nervous system
P	Antiparasitic products, insecticides and repellents
R	Respiratory system
S	Sensory organs
V	Various

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, like 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."

External links

• Official ATC website, hosted by the WHO Collaborating Centre for Drug Statistics Methodology
• ATC: Introduction on the Family Medicine Research Centre, University of Sydney