What is RxNorm?
RxNorm is a standardized nomenclature for clinical drugs produced by the U.S. National Library of Medicine (NLM). It provides normalized names and unique identifiers — called RxCUIs — that allow different drug databases, EHR systems, and pharmacy systems to communicate without ambiguity.
Maintained by
NLM / NIH
Updated
Weekly
Identifier
RXCUI (integer)
Coverage
~100K+ concepts
The RXCUI
Every concept in RxNorm — ingredients, drug forms, specific strengths, brand names — is assigned an integer identifier called an RXCUI (RxNorm Concept Unique Identifier). RxCUIs are stable: once assigned, an RXCUI is never reused for a different concept, even if the original concept is retired.
RXCUI: 617314-- TTY = SCD
Term Types (TTY)
Each RxNorm concept has a term type (TTY) that defines its level in the drug hierarchy. The most analytically useful types are SCD (generic drug + strength) and SBD (branded version).
| TTY | Name |
|---|---|
| IN | Ingredient |
| MIN | Multiple Ingredients |
| PIN | Precise Ingredient |
| BN | Brand Name |
| SCDF | Semantic Clinical Drug Form |
| SCD | Semantic Clinical Drug |
| SBD | Semantic Branded Drug |
| GPCK | Generic Pack |
| BPCK | Brand Pack |
SCD and SBD rows are highlighted — these are the primary identifiers for drug analytics.
The Drug Concept Hierarchy
RxNorm organizes drug concepts in a directed hierarchy from ingredient through clinical drug form to specific strength. This hierarchy is what makes RxNorm useful for cross-system aggregation: you can roll up NDCs (individual packages) all the way to a single ingredient concept.
| TTY | RXCUI | Name |
|---|---|---|
| IN | 83367 | Atorvastatin |
| SCDF | 310193 | Atorvastatin Oral Product |
| SCD | 617314 | Atorvastatin 10 MG Oral Tablet |
| SCD | 617318 | Atorvastatin 20 MG Oral Tablet |
| SCD | 617320 | Atorvastatin 40 MG Oral Tablet |
| SBD | 617321 | Lipitor 10 MG Oral Tablet |
Note that a single ingredient (RXCUI 83367) maps to one SCDF, which maps to multiple SCDs at different strengths. All branded products (SBD) link back to a corresponding generic SCD.
Why RxNorm Matters for Data Analytics
Cross-system normalization
Claims data, EHR data, and pharmacy data each use different drug identifiers. RxNorm provides a common concept layer. An NDC from a Medicaid claim can be mapped to an RXCUI, which can then be joined to clinical enrichment data, pricing benchmarks, or ATC classifications.
Ingredient-level roll-up
Analyzing spend or utilization at the ingredient level requires collapsing hundreds of NDCs (different strengths, packages, manufacturers) into a single concept. The SCD → SCDF → IN hierarchy makes this straightforward.
Generic/brand distinction
SCD is the generic concept; SBD is the branded equivalent. This relationship is explicit in RxNorm, making generic substitution analysis deterministic — no fuzzy matching required.
Stable identifiers
RxCUIs are persistent. Unlike NDCs (which can be reassigned to different drugs) or drug names (which vary by source), an RXCUI assigned to a concept remains valid indefinitely, even after a drug is retired.
Sample Data — drug_detail Table
Below is a representative sample from the TwinFyRx drug_detail table, showing how RxNorm concepts are stored with drug_id (RXCUI), term type, ingredient, and generic/brand classification.
| drug_id | drug_name | tty |
|---|---|---|
| 617314 | Atorvastatin 10 MG Oral Tablet | SCD |
| 617318 | Atorvastatin 20 MG Oral Tablet | SCD |
| 617321 | Lipitor 10 MG Oral Tablet | SBD |
| 197361 | Amlodipine 5 MG Oral Tablet | SCD |
| 314077 | Lisinopril 10 MG Oral Tablet | SCD |
| 860975 | Metformin 500 MG Oral Tablet | SCD |
| 213169 | Glucophage 500 MG Oral Tablet | SBD |
| 311700 | Omeprazole 20 MG Delayed Release Oral Capsule | SCD |
| 352304 | Duloxetine 30 MG Delayed Release Oral Capsule | SCD |
| 1049640 | Eliquis 5 MG Oral Tablet | SBD |
| 310429 | Levothyroxine 50 MCG Oral Tablet | SCD |
| 856845 | Gabapentin 300 MG Oral Capsule | SCD |
12 rows from the TwinFyRx drug_detail table. SBD (branded) rows highlighted. Full dataset contains 2,500+ SCD/SBD concepts. Download a free sample.
How TwinFyRx uses RxNorm
TwinFyRx is built on the full RxNorm release as its foundation layer. Every drug concept in the platform — including ICD-10 mappings, ATC classifications, NADAC pricing, and suspecting rules — is anchored to an RXCUI. The primary analytical key is drug_id (SCD/SBD RXCUI), with clinical_drug_form_rxcui (SCDF) as the join point for enrichment layers.