RxNorm — NLM Drug Terminology

Overview

RxNorm is a normalised naming system for clinical drugs produced and maintained by the US National Library of Medicine (NLM). It provides standard names and identifiers for medications at the clinical level, covering drug ingredients, strengths, dose forms, and branded and generic names, and links them to many drug vocabularies commonly used in pharmacy management and drug interaction software.

Concept Hierarchy

RxNorm organises drug concepts from most general to most specific:

• An ingredient is the active moiety (e.g. levodopa).
• A clinical drug component adds strength to an ingredient (e.g. levodopa 100 mg).
• A clinical drug form adds a dose form (e.g. levodopa oral tablet).
• A clinical drug specifies ingredient, strength, and dose form together (e.g. levodopa 100 mg oral tablet).
• A branded drug is the trade name version (e.g. Sinemet).
• A clinical or branded pack represents a multi-drug combination product.

Role in Clinical Data Standards

OMOP CDM uses RxNorm as its standard drug vocabulary; all medication records are mapped to RxNorm concept IDs via the OMOP Vocabulary (browsable at https://athena.ohdsi.org), with ATC used alongside RxNorm for drug class grouping. HL7 FHIR uses RxNorm codes in Medication and MedicationRequest resources as the standard US drug terminology.

Resources

• https://www.nlm.nih.gov/research/umls/rxnorm/
• https://mor.nlm.nih.gov/RxNav/ (RxNav browser)
• https://athena.ohdsi.org (OMOP Vocabulary including RxNorm)