1.0 Introduction

RxNorm, a standardized nomenclature for clinical drugs, is produced by the National Library of Medicine. In this context, a clinical drug is a pharmaceutical product given to (or taken by) a patient with a therapeutic or diagnostic intent. In RxNorm, the name of a clinical drug combines its ingredients, strengths, and form.

In RxNorm, the form is the physical form in which the drug is administered or is specified to be administered in a prescription or order. The RxNorm clinical drug name does not refer to the size of the package, the form in which the product was manufactured, or its form when it arrived at the dispensary.

RxNorm's standard names for clinical drugs are connected to the varying names of drugs present in many different controlled vocabularies within the Unified Medical Language System (UMLS) Metathesaurus, including those in commercially available drug information sources. These connections are intended to facilitate interoperability among the computerized systems that record or process data dealing with clinical drugs.

Like other vocabularies in the Metathesaurus, RxNorm is organized by concept or meaning. All concepts in RxNorm are assigned at least one semantic type from the Semantic Network (Section 3.0 of the UMLS documentation). This provides consistent categorization of all concepts in RxNorm at the relatively general level represented in the Semantic Network.

2.0 Scope of RxNorm

RxNorm is both a source and a subset of the Metathesaurus. The scope of RxNorm is determined by the combined scope of its source vocabularies. Many relationships (primarily synonymous), concept attributes, and some concept names are added by the NLM during the creation of RxNorm forms, but essentially all the concepts themselves come from one or more of the source vocabularies.

3.0 Preservation of Content and Meaning from Source Vocabularies

RxNorm reflects and preserves the meanings, concept names, and relationships from its source vocabularies in the same way that the Metathesaurus preserves content and meaning. Please refer to the UMLS Metathesaurus documentation for further information on this topic.

RxNorm contains source vocabularies produced by different copyright holders. The majority of the content of RxNorm is available for use under the basic and open terms described in sections 1-11 and 13-16 of the Metathesaurus license. Please refer to the UMLS Metathesaurus documentation for further information on this topic.

4.0 Drug Delivery Devices

The RxNorm model of a prescribable drug, which specifies the ingredient, strength, and dose form, adequately represents most prescriptions for medicines. However; there are some important medicines not sufficiently or appropriately characterized by those three components alone. These have been identified as medicines that are dispensed in "Packs". For example, Z-Pak, Medrol Dose Pack, and various oral contraceptive packages. A Pack would contain one or more SCD's or SBD's along with a quantification to represent the number of SCD's or SBD's of a certain type that are contained in the Pack.

Packs may be branded or generic packs. A Branded Pack would contain SBD's and/or SCD's and be provided with a Market Name, while a Generic Pack would contain one or more SCD's only. The new Term Types "BPCK" and "GPCK" have been created to represent these strings in the RxNorm vocabulary. The representation of these strings in RxNorm consists of the following syntax:

Examples of BPCK's:

Examples of GPCK's:

Each BPCK atom has a corresponding GPCK atom. These atom pairs will be represented with relationships in the RXNREL.RRF file in the following way:

In addition, relationships are created between the Drug Delivery Device term type atoms (BPCK, GPCK), to their component SCD(s) and/or SBD(s). These relationships are represented in the RXNREL.RRF file in the following way:

5.0 Normalizing NDC codes in RxNorm

RxNorm currently distributes NDC data from four different sources. Each of these sources provides NDC codes in a different format. Examples of these include a 14 digit "6-4-2" format, 10 digit "5-3-2", "4-4-2" or "5-4-1" formats, 12 digits with no dashes format, and the 11 digit, no dashes HIPAA format.

The NDCs asserted for the atoms of each of these sources are found in RXNSAT.RRF as values of the attribute ATN='NDC'. Since these NDCs are in separate formats, it is difficult to determine when the NDC assignments are inconsistent across sources. A single RxNorm clinical drug concept may properly have several NDCs (each corresponding to a different package size), but a single NDC would be expected to be assigned to only one RxNorm clinical drug concept (RXCUI).

The NLM is associating normalized NDC codes to RxNorm clinical drugs of the term types 'SCD', 'SBD', 'BPCK' and 'GPCK' (SAB=RXNORM atoms). The normalized NDCs will follow the 11 digit, no dashes HIPAA format. These normalized NDCs will be associated with an RXCUI where the NLM can determine the "correct" NDCs for that RXCUI. In general, "correctness" of an NDC assignment means there is consistency among the various sources in the association of an RXCUI with a particular NDC. These normalized NLM-asserted NDC associations will be found in RXNSAT.RRF, in additon to all the source-asserted NDC associations that already appear there. The normalized NLM-asserted NDC associations are assigned SAB='RXNORM'.

5.1 Examples of NDC code normalizations

5.2 Examples of RXNSAT.RRF entries for an RXCUI (ATN="NDC")

6.0 Propagating NDC codes in RxNorm

As noted above, a single NDC code should properly be associated with only a single RxCUI, though a single RxCUI can have multiple NDCs. RxNorm takes a slight liberty with this principle, and propagates the NDCs for branded drugs to the corresponding unbranded drugs. In other words, RxNorm associates the NDC for a branded drug with both the branded and unbranded counterparts of an SBD. This is done to make it easy for users to find all the NDCs associated with a particular drug, both the branded and unbranded versions of that drug. This means that the NDC for an SBD would be associated with multiple RxCUIs, i.e. the RxCUI for the SBD as well as the RxCUI for the corresponding SCD.

For Drug Delivery Devices, an NDC associated with a multi-component BPCK will propagate and be associated with the corresponding GPCK as well. For single component BPCKs and GPCKs, their NDC codes will propagate to the associated SBDs and SCDs contained within those drug delivery devices atoms.

7.0 Duplicating Source Asserted Atoms

Atoms coming from our sources can contain multiple NDC codes for the same atom. In many cases the NDC codes associated with the atoms are describing a similar product. However, there are cases where NDC codes received from sources for the same atom carry different meanings. For example, a source atom may contain "CAP/TAB" as the dose form portion of the atom and have the NDC codes for both the capsule form of the drug and the tablet form of the drug associated to this one atom.

RxNorm is creating duplicates of such source asserted atoms in order to properly associate NDC codes with RxNorm forms. When an atom is duplicated, the original source atom is considered to be a 'Base' atom and it is not assigned an RxNorm form. The duplicate atom's string is created by appending '_#N' to the Base atom string where 'N' is a number from 1 to N number of duplicates for this base atom.

The duplicate atoms will carry the same source asserted relationships and attributes as the Base atom except for the NDC code attributes. The NDC code attributes of the base atom will be assigned to the duplicate atoms that represent the different meanings of the base atom. RxNorm forms will be created to reflect the true meaning of the NDC code(s) assigned to each duplicate. An NDC code from a base atom can only be assigned to one duplicate atom at a time, but a duplicate atom can carry more than one similar meaning NDC codes from the base atom. The duplicate atom's term type will be created by prepending 'MTH_RXN_' to the base atom's term type.

A Base atom can be identified by the existence of an attribute in RXNSAT.RRF where the ATN='AMBIGUITY_FLAG' and the ATV='Base'. Similarly, the duplicate atoms are identified with ATN='AMBIGUITY_FLAG' and ATV='Duplicate'. This attribute will carry the SAB of the base atom. In addition, a relationship will exist between the base atom and it's duplicate atoms in RXNREL.RRF with "includes" and "included_in" relationship attributes (RELA). This relationship will carry the SAB of the base atom.

Examples of RXNCONSO.RRF entries for a base atom and it's duplicates

Examples of RXNSAT.RRF entries for these atoms (ATN="AMBIGUITY_FLAG")

Examples of RXNREL.RRF entries for these atoms

8.0 Drug Dose Forms and the Modified Format for SCD and SBD Normal Forms

To accurately represent factors of time, measures or strength for certain dose forms within RxNorm, an additional format for SCD and SBD forms has been utilized along with a more succinct set of dose forms for certain categories of forms. The factor of time, measure or strength can now be represented by a Quantity Factor appended to the beginning of the SCD or SBD name. This quantity factor consists of a number followed by a unit measure. The number might represent a strength, a unit of time, or a quantity of dosages depending upon the dosage form in use at the time. This quantity factor is stored as an attribute to the RxNorm SAB atom as the value of the ATN='RXN_QUANTITY' in RXNSAT.RRF. Some dose forms have been retired and replaced by more generic dose form names, allowing for greater flexibility in representing drug names. Other dose forms have been added.

The following dose forms have been replaced by the more generic dose form shown to the right of the name. The Quantity number is variable according to the clinical drug being represented.

Example RxNorm forms before the data transformation:

     Bupropion 300 MG 24 hour Extended Release Tablet [Wellbutrin]
     Clonidine 0.00833 MG/HR Weekly Transdermal Patch

And after the data transformation:

     24 HR Bupropion 300 MG Extended Release Tablet [Wellbutrin]
     168 HR Clonidine 0.00833 MG/HR Transdermal Patch

The following dose forms have been added to the RxNorm vocabulary. For these dose forms, a quantity factor is required.

All other dose forms in RxNorm may contain an optional quantity factor.

Example forms are shown below:

     3 ML Insulin, Aspart, Human 100 UNT/ML Prefilled Syringe
     2 ML hyaluronate 10 MG/ML Prefilled Syringe [Hyalgan]

The process of using these new dose forms and transforming RxNorm forms to the new format is currently ongoing.

Examples of RXNSAT.RRF entries for an RXCUI (ATN="RXN_QUANTITY")

8.1 Deprecating Syrup and Elixir Dose Forms

In an effort to reduce the discrepancies related to NDC codes on RxNorm forms, beginning with the March 2008 release, RxNorm will be using the Oral Solution dose form in lieu of the Syrup and Elixir dose forms. Existing RxNorm normal forms (SCD, SBD, SCDF, SBDF) using Syrup and Elixir have been transformed into RxNorm normal forms using the Oral Solution dose form. In some cases, this process resulted in new RxNorm forms being created, in others, an RxNorm form already existed and was reused. The RxNorm normal forms that contained Syrup and Elixir dose forms have been archived.

9.0 Release Types and Explanation

This Full release of RxNorm is consistent with the 2008AA UMLS Metathesaurus release.

This release contains updates to seven sources (GS, MDDB, MMSL, MMX, MTHSPL, NDDF, and VANDF), and no updates to the following sources: (MTHFDA and SNOMEDCT)

9.1 The following counts apply for this release of RxNorm:

The content of the RXNSAB.RRF file has been modified to reflect changes required by the UMLS. The number of fields in RXNSAB has not changed, but the format of the following fields have been expanded and include semi-colon separated information. The fields affected are: Source License Contact (SLC), Source Content Contact (SCC), and the Source Citation (SCIT). Please refer to the RXNSAB.RRF detailed documentation within this document for more information.

New since the July 2007 release is the RXNCUICHANGES.RRF file. This file contains information about changes to the RxNorm Concept_id (RXCUI) for source asserted atoms and for the RxNorm forms (SAB=RXNORM atoms) that have been archived. More information may be found about this file beginning at this portion of this document.

In addition, this release contains database control files and SQL commands for use in the automation of the loading process of these files into a RDBMS. Scripts and controls are provided for the loading the RxNorm files into an Oracle database or a MySQL database.

This release contains complete sets of data and the RxNorm forms (RXNORM source) for the following RxNorm drug data source providers:

• GS - 05/01/2008 (Gold Standard Alchemy)
• MDDB - 05/07/2008 (Master Drug Data Base. Medi-Span, a division of Wolters Kluwer Health)
• MMSL - 05/01/2008 (Multum MediSource Lexicon)
• MMX - 05/05/2008 (Micromedex DRUGDEX)
• MTHFDA - 04/04/2008 (FDA National Drug Code Directory)
• MTHSPL - 05/22/2008 (FDA Structured Product Labels)
• NDDF - 05/09/2008 (First DataBank NDDF Plus Source Vocabulary)
• SNOMED CT - 01/31/2008 (SNOMED Clinical Terms (drug information). SNOMED International)
• VANDF - 04/10/2008 (Veterans Health Administration National Drug File)

The most complete, accurate and up-to-date drug information can be obtained from the use of these RxNorm Release files.

9.2 Character Encoding

The character set of RxNorm Release Files is Unicode UTF-8

9.3 RxNorm Release File Format

RxNorm uses the Rich Release Format (RRF), introduced in 2004. All Rich Release Format file names have an extension (.RRF). The RxNorm Rich Release Format is described in this documentation (usually abbreviated as RXNRRF). Refer to the UMLS Metathesaurus documentation for a complete description of the RRF.

9.4 RxNorm Conventions

RxNorm follows all previously established standards and practices of the latest version of the UMLS Metathesaurus. Where RxNorm may differ slightly from these practices is documented here.

9.5 Uses of Concept and Atom Identifiers

In RxNorm, every RXCUI (concept) is linked to at least one RXAUI (atom), but can be linked to many of these. Every RXAUI (atom) is linked to a single RXCUI (concept).

10.0 Data Files - RxNorm Rich Release Format (RXNRRF)

All file names begin with the letters RXN (RxNorm) and are followed by letters that denote the file contents (e.g., RXNREL=relationships, RXNSAB=source abbreviations), and then a file extension .RRF.

The data in each RxNorm entry may be represented in different "relations" or files. These files correspond to the four logical groups of data elements described in Sections 2.2 - 2.5 of the Metathesaurus documentation. The exceptions to this rule are the RXNATOMARCHIVE.RRF and the RXNCUICHANGES.RRF files.

The RXNATOMARCHIVE.RRF file is a file created by RxNorm for use in tracking the archival of names (atoms) no longer provided by RxNorm drug source providers, or atoms no longer used by the RxNorm system. Only atoms from the source RxNorm (SAB=RXNORM) will be in the archive.

The RXNCUICHANGES.RRF file is a new file provided by RxNorm for use in tracking the changes to the RxNorm Concept_id (RXCUI) for source asserted atoms, RxNorm OCD atoms, and for RXCUI changes to RxNorm forms (SAB=RXNORM atoms) that have been archived in the RXNATOMARCHIVE.RRF file. For each release, this tracking is provided for data changed since the last release of RxNorm. The data file is not cumulative.

RxNorm provides data in the following types of files:

Concepts, Concept Names, and their sources (2.2) = RXNCONSO.RRF

Attributes (2.3) = RXNSAT.RRF, RXNSTY.RRF

Relationships (2.4) = RXNREL.RRF

Data about RxNorm (2.5) = RXNDOC.RRF, RXNSAB.RRF

Archive Data = RXNATOMARCHIVE.RRF

Concept Changes Tracking Data = RXNCUICHANGES.RRF

10.1 Columns and Rows

Each file or named table of data values has by definition a fixed number of columns; the number of rows depends on the content of a particular version of the RxNorm. The RxNorm release files follow the format of the Metathesaurus releases files with a few exceptions which are noted below.

10.2 Descriptions of Each File

The descriptions of the files appear in the following order:
a) Key data about the Metathesaurus: Files; Columns or data elements; Documentation that explains the meaning of abbreviations that appear as values in Metathesaurus data elements and attributes,
b) Concept names and their vocabulary sources
c) Attributes
d) Relationships
e) Other data about RxNorm

Each file description lists the columns or data elements that appear in the file and includes sample rows from the file.

10.3 Documentation for Abbreviated Values (File = RXNDOC.RRF)

This file follows the format of the Metathesaurus MRDOC.RRF file. At this time, this file contains all of the data contained in the UMLS MRDOC.RRF file. In the furture, the contents of this file may be tailored to the RxNorm subset of data only. There is exactly one row in this table for each allowed value of selected data elements or attributes that have a finite number of abbreviations as allowed values. Examples of such data elements include TTY, ATN, TS, STT, REL, RELA.

Sample Records

ATN|DDF|expanded_form|Drug Doseform|
ATN|DHJC|expanded_form|HCPCS J-code|

10.4 Concept Names and Sources (File = RXNCONSO.RRF)

This file follows the general format of the MRCONSO.RRF file of the Metathesaurus. Some of the Metathesaurus fields are not provided by RxNorm and are marked as "(no value provided)". There is exactly one row in this file for each atom (each occurrence of each unique string or concept name within each source vocabulary) in RxNorm, i.e., there is exactly one row for each unique RXAUI in RxNorm. Every string or concept name in RxNorm appears in this file, connected to its language, source vocabularies, and its concept identifier (RXCUI).

Sample Records

91348|ENG|P||PF||Y|707001|707001|91348||RXNORM|SCD|RX10091348|Hydrogen Peroxide 300 MG/ML Topical Solution||||
83|ENG|P||VC||Y|1960||||SNOMEDCT|PT|75368007|4-Hydroxyphenylpyruvate dioxygenase||||
83|ENG|P||VC||Y|1960||||SNOMEDCT|PT|75368007|4-Hydroxyphenylpyruvate dioxygenase||||
2809|ENG|S||PF||Y|84238|84238|2809||RXNORM|OCD|10002809|CONTACT LENS EACH||O||

10.5 Simple Concept and Atom Attributes (File = RXNSAT.RRF)

This file follows the general format of the MRSAT.RRF file of the
Metathesaurus. Some of the Metathesaurus fields are not provided by RxNorm and are marked as "(no value provided)". There is exactly one row in this table for each concept, atom, or relationship attribute that does not have a sub-element structure. Not all RxNorm concepts or RxNorm relationships have entries in this file. This file includes all source vocabulary attributes that do not fit into other categories.

Sample Records

178|||4996|AUI|MTHU000146|AT32525185||TYPE|MMSL|bulk compounding chemicals|N||
327|||9866|AUI|10000327|AT45601455||ORIG_CODE|RXNORM|003263|N||

10.6 Semantic Types (File = RXNSTY.RRF)

This file follows the general format of the MRSAT.RRF file of the
Metathesaurus. There is exactly one row in this file for each Semantic Type assigned to each concept. All RxNorm concepts have at least one entry in this file. Many have more than one entry. The TUI, STN, and STY are all direct links to the UMLS Semantic Network.

Sample Records

44|T109|A1.4.1.2.1|Organic Chemical|||
7624|T122|A1.4.1.1.2|Biomedical or Dental Material|||

10.7 Related Concepts (File = RXNREL.RRF)

This file follows the general format of the MRREL.RRF file of the
Metathesaurus. Some of the Metathesaurus fields are not provided by RxNorm and are marked as "(no value provided)". There is one row in this table for each relationship between concepts or atoms known to RxNorm. In addition, explicit SY RELs are provided which give the UMLS Metathesaurus CUI and AUI as the RXCUI2 and RXAUI2 fields.

Note that for asymmetrical relationships there is one row for each direction of the relationship. Note also the direction of REL - the relationship which the SECOND concept or atom (with Concept Unique Identifier RXCUI2 and Atom Unique Identifier RXAUI2) HAS TO the FIRST concept or atom (with Concept Unique Identifier RXCUI1 and Atom Unique Identifier RXAUI1).

Sample Records

353653|1553161|AUI|RO|102931|779853|AUI|consists_of|||RXNORM||||||
102931|779853|AUI|SY|C0351134|A2616052|AUI||||RXNORM||||||

10.8 Source Information (File=RXNSAB.RRF)

This file follows the general format of the MRSAB.RRF file of the
Metathesaurus. Please refer to the UMLS Metathesaurus documentation for more specific information regarding this file.

There is one row in this file for every source in RxNorm that is represented in this RxNorm release.

The structure of RXNSAB.RRF is as follows:

Sample Record:
1509846|C1140284|RXNORM_07AB_070702F|RXNORM|RxNorm Vocabulary|RXNORM|07AB_07070 2F|||2007AB||Stuart Nelson, M.D. ;Head, MeSH Section;National Library of Medicine;8600 Rockville Pike;;Bethesda;Maryland;United States;20894;;;nelson@nlm.nih.gov; |Stuart Nelson, M.D. ;Head, MeSH Section;National Library of Medicine;8600 Rockville Pike;;Bethesda;Maryland;United States;20894;;;nelson@nlm.nih.gov;|0||||BN,DF, ET,IN,OCD,SBDC,SBDF,SBD,SCDC,SCDF,SCD,SY|NDC,ORIG_CODE,ORIG_SOURCE,ORIG_TTY,ORIG _VSAB,RXAUI,RXCUI,RXN_OBSOLETED,RXN_ACTIVATED,RXN_BN_CARDINALITY,RXN_IN_STRENGTH _FLAG,RXN_QUANTITY|ENG|UTF-8|Y|Y|RxNorm work done by the National Library of Med icine|;;;;RxNorm;;;META2007AB Full Update 2007_07_02;Bethesda, MD;National Library of Medicine;;;;;;;;|

10.9 Archive Data (File = RXNATOMARCHIVE.RRF)

This file contains data about RxNorm SAB names (atoms) that are no longer a part of the RxNorm database because the drug data source provider is no longer providing this name to RxNorm. This file is not similar to any Metathesaurus RRF files. It is newly created by RxNorm.

The structure of RXNATOMARCHIVE.RRF is as follows:

Sample Records:
1138734|A0540716|Cefotetan Disodium|3/15/2005 8:05:03 PM|3/10/2005 2:56:21 PM| 3/15/2005 8:05:02 PM|10203141||ENG||||203141|RXNORM|IN|203141

2057262|2057262|Testosterone / Testosterone Injectable Solution [Andro-Cyp 100]|3/17/2005 2:01:59 PM| 3/16/2005 12:23:16 PM|3/17/2005 2:01:58 PM|10363337||ENG||||363337|RXNORM|SBDF|363337

10.10 Concept Changes (File = RXNCUICHANGES.RRF)

This file provides information about changes to the concept_id (RXCUI) for atoms in RxNorm from release to release. For source asserted atoms and SAB=RxNorm OCD term type atoms, all data fields will be populated. For RXCUI changes to RxNorm forms that have been archived, only the SAB, OLD_RXCUI, and NEW_RXCUI will be provided. Full information about RxNorm forms that have been archived can be found in the RXNATOMARCHIVE.RRF file. Information is provided here as a convenience. The file provides data about changes since the last release of RxNorm, it is not cumulative.

This file is not similar to any Metathesaurus RRF file. It is newly created by RxNorm.

Sample Records:

11.0 Database Creation Automation

We are providing scripts and control files to help in the creation and automation of your database loading with the RxNorm Release Files.

11.1 Oracle database

The populate_oracle_rxn_db.bat file contains 4 parameters, which should be customized for your particular environment. They are as follows:

Once these parameters are populated, you should remove the '::' (double colon) characters from the front of each line - this will make the commands active.

Use the RxNormDDL.sql file to create the tables in your database schema (the schema must already exist), then use the .bat file to load the data into your tables. Once this is complete you may run the rxn_index.sql to create indexes on the tables, if so desired.