RxNorm

RxNorm is a normalized naming system for clinical drugs and drug-related materials maintained by the National Library of Medicine (NLM). It provides standard identifiers for medications at multiple levels of granularity — from active ingredient to branded product to specific clinical dose form and strength. RxNorm concept unique identifiers (RxCUIs) enable pharmacy systems, EHRs, clinical decision support engines, and health information exchanges to exchange medication information without ambiguity, even when originating systems use different proprietary drug databases such as First Databank, Multum, or Micromedex.

RxNorm's data model distinguishes between several concept types: ingredients (e.g., metformin), clinical drugs (e.g., metformin 500 mg oral tablet), branded drugs (e.g., Glucophage 500 mg tablet), drug packs, and more. Relationships between these concept types are formally encoded, so a clinical decision support rule written at the ingredient level automatically applies to all branded and generic formulations. This hierarchical structure is essential for medication reconciliation, allergy checking, drug-drug interaction screening, and formulary management.

RxNorm is a required standard under the ONC Health IT Certification Program for medication lists and is the preferred code system for MedicationRequest, MedicationStatement, and MedicationAdministration resources in HL7 FHIR. The NLM provides RxNorm as a free download and through the RxNav API, which supports drug lookup, normalization, interaction checking via RxClass, and NDC-to-RxNorm mapping. NDC (National Drug Code) cross-references are particularly important for pharmacy dispensing systems, which use NDC codes at the point of dispensing but need RxNorm identifiers for clinical interoperability.

Engineering teams building medication management modules must handle the complexity of RxNorm's weekly update cycle, NDC mapping ambiguities, and the challenge of normalizing free-text medication entries from scanned documents or legacy systems. Clinical NLP pipelines that extract medication information from clinical notes must map to RxNorm as a final normalization step. Organizations using FHIR for medication exchange must also handle concept mapping between RxNorm and SNOMED CT for clinical summary documents and must manage value set governance to ensure formularies and allergy lists remain current.

Compliance-Native Architecture Guide

Design principles and a structured checklist for building software that is compliant by default — not compliant by retrofit. Covers data architecture, access controls, audit trails, and vendor due diligence.