The World Health Organization Collaborating Center for Drug Statistics Methodology produces and maintains the Anatomical Therapeutic Chemical Classification System with Defined Daily Doses (ATC/DDD).
The Metathesaurus includes ATC information only.
ATC classifies therapeutic drugs to enable drug research and to improve the quality of drug use.
ATC classifies drugs at five different levels. Each level is a different grouping of drugs. Groupings of active substances include the organ or system on which the drug acts as well as therapeutic, pharmacological, and chemical properties of the drug.
The Metathesaurus representation of ATC includes ingredients and drug classes.
The Metathesaurus representation of ATC has approximately 5,067 ingredients and 1,264 drug classes.
ATC is updated annually.
Metathesaurus Update Frequency
ATC is updated annually in each May release (AA) as part of RxNorm.