RxNORM Hierarchy

This tool displays the hierarchical organization of medications, including their variants in brand and dosage forms as classified in the RxNorm system. It also presents a knowledge graph that maps medicines from RxNorm codes to other prevalent coding systems like ATC and VA. Users can search by drug name or drug class to suit their analytical needs.

  1. RxNorm System

RxNorm is a standardized nomenclature for clinical drugs and devices for drug delivery that is created and maintained by the U.S. National Library of Medicine. Each clinical drug identifier (RxCUI) is structured to contain its active ingredient, strength, and dosage form.

  1. ATC Class

The Anatomical Therapeutic Chemical (ATC) classification system, developed by the World Health Organization (WHO), categorizes drugs based on their target organ or system and their therapeutic, pharmacological, and chemical properties. It organizes drugs into a five-level hierarchy, ranging from broad therapeutic groups to specific chemical substances.

  1. VA Class

The VA (Veterans Affairs) classification system, used primarily in the United States, categorizes medications based on their therapeutic use and pharmacologic characteristics. Similar to the ATC system, it provides a hierarchical structure that organizes drugs into groups and subgroups, reflecting their therapeutic relationships and mechanisms of action.

Quick Start Guide

To search by drug name:

  1. Click “Drug” on top left corner under the phrase “Search for”

  2. Select an RxNorm term from the data table. Alternatively, type the name of a medicine in the search box on the top of the table to apply filtering conditions, and then select a term

  3. Click on “Show/hide NDC” to show the Status and NDC column.

  4. Look for detailed info of the selected rug on the right

  5. Look for hierarchical structures below in 4 different tabs

    • “Related drugs”: hierarchical structure involving selected drug and its variants in RxNorm system
    • “Classes”: hierarchical structure showing the relationship between selected drug in RxNorm classification (purple) and relevant classes of drug in ATC (blue) and VA (green) classification respectively.

To search by drug class:

  1. Click “Class” on top left corner under the phrase “Search for”

  2. Type the name of the drug class of interest in the search box. From the search result table, three columns will be displayed: Source, Class and Rxnorm. Click on individual source and class to expand, and then select a RxNorm term of interest

  3. Same Step 4 as above

  4. Same Step 5as above

About App

  1. RxNorm Info (top left)

    • Rxcui: code of the drug in RxNorm system
    • Name: official name of the drug in RxNorm system
    • Term Type: term type of the drug, indicates generic and branded drug names at different levels of specificity. A full list of term types and their full description can be found in: https://www.nlm.nih.gov/research/umls/rxnorm/docs/appendix5.html
    • Status: Status of the RxNorm term. Hidden by default. Except for Acitve, other status are grayed out in the table.
      • Active The concept is in the current RxNorm data set and has a non-suppressed term (SUPPRESS=“N” in RXNCONSO) from the RxNorm vocabulary (SAB=“RXNORM” in RXNCONSO).
      • Obsolete The concept is designated as obsolete (SUPRRESS=“O” in RXNCONSO) in the current data set. RxNorm has not designated any Active concept as equivalent.
      • Remapped The concept was Active or Obsolete at one time, but is not in the RXNCONSO file in the current data set and has been remapped (in RXNATOMARCHIVE) to one or more Active or Obsolete concepts. Those concepts are returned in the remappedConcept element.
      • Quantified (The concept has been designated as non-dispensable for lack of a quantity factor (SUPPRESS=“E” in RXNCONSO). Related concepts with a quantity factor are returned in the quantifiedConcept element.)
      • NotCurrent The concept satisfies one of the following conditions: The concept exists in the current data set but has no RxNorm vocabulary terms. The concept existed in previous monthly versions, but has been removed and is not remapped to any Active or Obsolete concepts.
      • Unknown: The RxCUI has never been present in an RxNorm monthly release.
    • NDC: National Drug Code with an 11-digit format.

  2. Drug Info (top right)

    • ID: the same as RxCUI in table.
    • Term Type: the same as tty in table.
    • Status: the same as Status in table.
    • Semantic Type: broad categories of medicine where the drug fallsin , denoted by the Semantic Network created as a part of UMLS
    • Ingredient (ID): the same as ID
    • Ingredient (String): the same as official name of drug

  3. Related drugs (tab 1)

hierarchical structure involving selected drug and its relatives that fall under different brands, dosage (with corresponding units) and dosage form (e.g. tablet, liquid). The root of the hierarchical tree is the parent drug class with common atomic ingredient. The nodes are colored in their respective Term Type.

  1. “Classes”: TBD (tab 2)

Hierarchical structure showing where the selected drug (color purple for RxNorm) fall under target organ or system and their therapeutic purpose, under both ATC (color in blue) and VA classification (color in green)

Use Cases

In EHRs and billing documents, prescriptions are commonly encoded in RxNorm codes, which do not explicitly convey the therapeutic areas or target organ systems. The RxNorm hierarchical tool displays drugs and their equivalents within the RxNorm classification; it also maps these medications to their therapeutic uses, integrating both ATC and VA classification systems. This dual mapping enhances the understanding of a drug’s clinical application and facilitates clinical research.

RXNORM Info

Related Drugs