Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Unified Medical Language System® (UMLS®)

ATC Source Information

Click on a topic below the Source Synopsis section to display details.

Source Synopsis

Web site:
https://www.whocc.no/atc/structure_and_principles/

Authority
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 RxNorm includes ATC information only.

Purpose
ATC classifies therapeutic drugs to enable drug research and to improve the quality of drug use.

Description
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.

RxNorm Scope
The RxNorm representation of ATC includes ingredients and drug classes.

Update Frequency
ATC is updated annually.

RxNorm Update Frequency
ATC is updated annually in RxNorm, typically in the February RxNorm monthly release.

Sites Consulted

  1. WHOCC - Home [Internet]. Oslo: WHO Collaborating Centre for Drug Statistics Methodology [updated 2018 Feb 15]. ATC/DDD methodology - History. WHOCC; c2018 [cited 2020 Oct 12]. Available from: https://www.whocc.no/atc_ddd_methodology/history/.
  2. WHOCC - Home [Internet]. Oslo: WHO Collaborating Centre for Drug Statistics Methodology [updated 2018 Nov 26]. ATC - Structure and Principles; [updated 2018 Feb 15; cited 2018 Dec 7]. Available from: https://www.whocc.no/atc/structure_and_principles/.

Metadata

Field Value
Short NameAnatomical Therapeutic Chemical Classification System
FamilyATC
Source Restriction Level0
LanguageENG
License ContactWHO Collaborating Centre for Drug Statistics Methodology
Norwegian Institute of Public Health
P.O.Box 4404 Nydalen
Oslo
Norway
0403
+47 21 07 81 60
+47 21 07 81 46
whocc@fhi.no
http://www.whocc.no/copyright_disclaimer/
Content ContactWHO Collaborating Centre for Drug Statistics Methodology
Norwegian Institute of Public Health
P.O.Box 4404 Nydalen
Oslo
Norway
0403
+47 21 07 81 60
+47 21 07 81 46
whocc@fhi.no
http://www.whocc.no/

Source Representation

This section lists specific source data elements and provides information on their representation in RxNorm.

Summary of Changes

There are no changes to the original data format or to RxNorm source processing.

Source Provided Files:

The ATC file is available from: 

https://www.whocc.no/atc_ddd_index_and_guidelines/atc_ddd_index/

The following file is used for RxNorm source processing.

File Name

Description

<YYYY> ATC Index with

 DDDs_electronic version.xlsx

Excel file containing information on codes and levels


Source-Provided Files: Details

The following is a list of fields in the ATC source files used in RxNorm processing and their representations in RxNorm.

Consult the ATC web site for additional ATC information at: https://www.whocc.no/atc/structure_and_principles/

File name: 2023 ATC Index with DDDs_electronic version.xlsx; only the first tab, “ATCIndeks with DDDs 2023” is processed


#

ATC Field Name

Description

RxNorm Representation

1

ATC Code

1-7 character alphanumeric code for the ATC name

RXNCONSO.CODE


RXNSAT.ATN = ATC_LEVEL

Levels are implied by the number of characters in the ATC code:

1 character:  Level 1

3 characters: Level 2

4 characters:  Level 3

5 characters: Level 4

7 characters: Level 5


RXNREL.RRF

Used to derive hierarchical relationships:

Levels 1-4:

REL = PAR/CHD

RELA = inverse_isa/isa

Level 5: 

REL = PAR/CHD

RELA = has_member/member_of

2

ATC level name

ATC substance name

In the ATC classification system, the active substances are classified in a hierarchy with five different levels.  The system has fourteen main anatomical/pharmacological groups or 1st levels.  Each ATC main group is divided into 2nd levels which could be either pharmacological or therapeutic groups.  The 3rd and 4th levels are chemical, pharmacological or therapeutic subgroups and the 5th level is the chemical substance.  The 2nd, 3rd and 4th levels are often used to identify pharmacological subgroups when that is considered more appropriate than therapeutic or chemical subgroups.

RXNCONSO.STR

TTY = PT for levels 1-4

TTY = IN for level 5


3

DDD

Not applicable

Not applicable

4

Unit

Not applicable

Not applicable

5

Adm.R

Not applicable

Not applicable

6

Comment

Not applicable

Not applicable


RxNorm Representation

This section lists RxNorm data elements and traces them back to the specific ATC data that populates them.

Summary of Changes

There are no changes to the original data format or to RxNorm source processing.

Source Provided Files:

The ATC file is available from: 

https://www.whocc.no/atc_ddd_index_and_guidelines/atc_ddd_index/

The following file is used for RxNorm source processing.

File Name

Description

2023 ATC Index with

 DDDs_electronic version.xlsx

Excel file containing information on codes and levels


RxNorm Identifiers:

Identifiers are assigned as follows:

Identifier

Origin

CODE

ATC code

SAUI

Not applicable

SCUI

Not applicable

SDUI

Not applicable


Atoms (RXNCONSO):

Term Type

Origin

IN

ATC level name for Level 5 codes

PT

ATC level name for Level 1-4 codes

RXN_IN

Created by RxNorm editors for disambiguation purposes, based on the hierarchy

RXN_PT

Created by RxNorm editors for disambiguation purposes, based on the hierarchy


Relationships (RXNREL):

REL/inverse REL

RELA/inverse RELA

Origin

PAR/CHD

has_member/member_of

Hierarchical relationship connecting Level 5 (chemical substance) to Level 4 subgroup (IN to PT)

PAR/CHD

inverse_isa/isa

Hierarchical relationships connecting Levels 1-4 (PT to PT)


Attributes (RXNSAT):

ATN

Origin

ATC_LEVEL

Derived from ATC code:


1:  main anatomical/pharmacological groups

2.  Either pharmacological or therapeutic groups  

3,4:  Chemical, pharmacological or therapeutic subgroups

5:  Chemical substance

IS_DRUG_CLASS

“Y” for PT (level 1-4) codes

Data Examples with Sample Database Queries

This section lists source terminology specific data examples and sample database queries using Structured Query Language (SQL) to obtain the data. For more information about RxNorm data and files, see the RxNorm Technical Documentation.

Names and Codes in RXNCONSO.RRF

Here are sample source terminology code, source string, RxNorm Concept Unique Identifier (RXCUI), RxNorm string, RxNorm term type (TTY), and suppress values.

SOURCE_CODE SOURCE_STR RXCUI RXNORM_STR RXNORM_TTY SUPPRESS
C01EB16 ibuprofen 5640 Ibuprofen IN N
G02CC01 ibuprofen 5640 Ibuprofen IN N
M02AA13 ibuprofen 5640 Ibuprofen IN N
M01AE01 ibuprofen 5640 Ibuprofen IN N

Here is a sample database query to retrieve the data above:

SELECT distinct rc1.code as source_code, rc1.str as source_str, rc1.rxcui, rc2.str as rxnorm_str, rc2.tty as rxnorm_tty, rc2.suppress
FROM rxnconso rc1, rxnconso rc2
WHERE rc1.code in ('C01EB16', 'G02CC01', 'M01AE01', 'M02AA13')
     AND rc1.sab = 'ATC'
     AND rc1.rxcui = rc2.rxcui
     AND rc2.sab = 'RXNORM';

Names and Relationships in RXNCONSO.RRF and RXNREL.RRF

Here are sample source terminology code, source string, RXCUI, relationship name, RxNorm term type (TTY), brand name, and suppress values.

SOURCE_CODE SOURCE_STR RXCUI RELA RXNORM_TTY BN SUPPRESS
C01EB16 ibuprofen 5640 has_tradename BN Advil N
C01EB16 ibuprofen 5640 has_tradename BN Brufen N
C01EB16 ibuprofen 5640 has_tradename BN Motrin N
C01EB16 ibuprofen 5640 has_tradename BN Nuprin N

Here is a sample database query to retrieve the data above:

SELECT distinct rc1.code as source_code, rc1.str as source_str, rc1.rxcui, rr.rela, rc2.tty as rxnorm_tty, rc2.str as bn, rc2.suppress
FROM rxnconso rc1, rxnrel rr, rxnconso rc2
WHERE rc1.code = 'C01EB16'
     AND rc1.sab = 'ATC'
     AND rc1.rxcui = rr.rxcui2
     AND rr.rela = 'has_tradename'
     AND rr.rxcui1 = rc2.rxcui
     AND rc2.sab = 'RXNORM'
     AND rc2.tty = 'BN'
     ORDER BY suppress;

Last Reviewed: April 10, 2024