RxNORM Hierarchy

This tool illustrates the hierarchical structure of medications and their variants in brand and dosage form denoted in RxNorm systems. It also showcases the knowledge graph mapping medicine in RxNorm code to other common medicine coding systems, such as ATC and VA.

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.

2. 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.

3. 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

1. 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

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

3. Look for hierarchical structures below in 4 different tabs

   • “Related drugs”: hierarchical structure involving selected drug and its variants in RxNorm system
   • “Classes”:
     • “ATC Classes”: graph structure showing relationship between selected drug and relevant terms in ATC classification
     • “VA Classes”: graph structure showing relationship between selected drug and relevant terms in VA classification

About App

1. RxNorm Info (top left)

   • rxcui: code of the drug in RxNorm system
   • name: official name of the drug in RxNorm system
   • tty: 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

2. Drug Info (top right)

   • ID: the same as RxCUI
   • Term Type: the same as tty
   • Status: ??
   • 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

4. “Classes”: TBD (tab 2)

Hierarchical structure showing where the selected drug fall under target organ or system and their therapeutic purpose

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.