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.
In this system, drugs are classified into groups at 5 different levels:
The first level of the code indicates the anatomical main group and consists of one letter. There are 14 main groups:
|A||Alimentary tract and metabolism|
|B||Blood and blood forming organs|
|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|
|P||Antiparasitic products, insecticides and repellents|
The second level of the code indicates the therapeutic main group and consists of two digits.
The third level of the code indicates the therapeutic/pharmacological subgroup and consists of one letter.
Example: C03C High-ceiling diuretics
The fourth level of the code indicates the chemical/therapeutic/pharmacological subgroup and consists of one letter.
Example: C03CA Sulfonamides
The fifth level of the code indicates the chemical substance and consists of two digits.
Example: C03CA01 Furosemide
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.