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Unified Medical Language System (UMLS)

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MED-RT (Medication Reference Terminology) - Synopsis

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The Veterans Health Administration (VHA) produces the Medication Reference Terminology (MED-RT).  The VHA is a division of the U.S. Department of Veteran Affairs.

MED-RT is a replacement and successor to NDF-RT.  Both terminologies are formal ontological representations of medication terminology, pharmacologic classifications, and asserted authoritative relationships between them.

MED-RT includes native pharmacologic classification concepts (e.g. mechanisms of action (MoA), physiologic effects (PE), Established Pharmacologic Class (EPC)) and all relationships asserted between concepts in any namespace.

MED-RT incorporates the following terminologies:

  • RxNorm for prescribable medications, active ingredients, and relationships between them
  • MeSH for indexing chemical structure and therapeutics using its concept hierarchies
  • SNOMED CT International to aid in mapping between FDA pharmacologic classes and its product and substance hierarchies

MED-RT will maintain the pharmacologic classification relationships from NDF-RT.

It also maintains the National Committee on Vital and Health Statistics (NCVHS) standards for describing medication pharmacologic classification: MoA and PE hierarchy concepts. The concepts are components of the Federal Medication Terminologies (FMT) interagency collaboration.

Update Frequency
MED-RT is updated monthly.

Metathesaurus Update Frequency
MED-RT is updated in each release.

Sites Consulted

  1. National Cancer Institute [Internet]. Bethesda (MD): National Cancer Institute (US); [cited 2018 Apr 23]. Federal Medication Terminologies; [updated 2018 Apr 02; cited 2018 Apr 23]. Available from:; Introduction to MED-RT as the Replacement for NDF-RT