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Unified Medical Language System® (UMLS®)

2008AB National Drug File - Reference Terminology Source Information

The National Drug File – Reference Terminology (NDF-RT) is produced by the U.S. Department of Veterans Affairs, Veterans Health Administration (VHA).

NDF-RT is an extension of the VHA National Drug File (NDF). It organizes the drug list into a formal representation.

NDF-RT is used for modeling drug characteristics including ingredients, chemical structure, dose form, physiologic effect, mechanism of action, pharmacokinetics, and related diseases.

NDF-RT combines the NDF hierarchical drug classification with a multi-category reference model.

For more information about NDF in the Metathesaurus, see the NDF source synopsis.

Metathesaurus Scope
The Metathesaurus representation of NDF-RT includes only concepts above the "Packaged Product" level. Some attributes of concepts at this level have been attached to the parent product level concept, specifically:

  • VA_NDC (National Drug Code corresponding to a clinical drug),
  • VA_UPN (universal product number),
  • VA_RXO (drug description: R for prescription drugs and O for over-the-counter drugs), and
  • VA_TRN (trade name of product).

Update Frequency
NDF-RT is updated monthly.

Metathesaurus Update Frequency
NDF-RT is updated in the Metathesaurus as resources permit.

Sites Consulted

  1. Carter JS, Brown SH, Bauer BA, Elkin PL, Erlbaum MS, Froehling DA, Lincoln MJ, Rosenbloom ST, Wahner-Roedler DL, Tuttle MS. Categorical information in pharmaceutical terminologies. AMIA Annu Symp Proc. 2006:116-20. Cited in: PubMed; PMID 17238314. Available from: //
  2. Chute CG, Carter JS, Tuttle MS, Haber M, Brown SH. Integrating pharmacokinetics knowledge into a drug ontology: as an extension to support pharmacogenomics. AMIA Annu Symp Proc. 2003:170-4. Cited in PubMed; PMID: 14728156. About the HGNC; [updated 2007 Feb 16; cited 2008 Sep 17]. Available from: //