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API Updates

Transition from NDF-RT to MED-RT

The final version of the National Drug File Reference Terminology (NDF-RT) was released in February 2018. The Medication Reference Terminology (MED-RT) is the evolutionary successor to NDF-RT. The changes to RxNav and RxClass below were put in place on June 4, 2018.

Changes to Applications

RxNav and RxClass changed because of the NDF-RT to MED-RT transition.
  • RxNav. Changes include:
    • The NDF-RT tab was removed.
    • Under the Class View tab, the Drug and DF views were removed. They are replaced with EPC and VA class views. The Disease view now contains MeSH class nodes and uses the MED-RT drug-class relations. The Chem view also contains MeSH class nodes. The Chem, MoA, PE, and EPC views use the DailyMed drug-class relations. The PK view uses the MED-RT drug-class relations.
  • RxClass. Changes include:
    • The Edit Drug Sources table has a column labeled "MEDRT", replacing the "NDFRT" column. An additional column for the VA drug source was added.
    • CHEM The CHEM tree top level node was renamed from "Chemical Structure" to "Substances and Cells". The classes in this tree are (mostly) MeSH Descriptors, and so are identified by MeSH descriptor identifiers. Most of the MeSH classes contained in the RxClass CHEM tree are part of the drugs and chemicals ("D" tree) category in MeSH.
    • Disease. The Disease tree top level node was renamed from "Disease" to "Diseases, Life Phases and Physiologic States". The tree contains mostly MeSH Descriptors from the diseases ("C" tree) category, and so are identified by MeSH descriptor identifiers.
    • MED-RT drugs directly refer to RxNorm, so the source id and source name fields in the output tables (displayed when the "show source data" box is checked) contain RxNorm identifiers and names for the drugs in classes EPC, Disease, Chem, MoA, PK and PE.
    • Output table notation says MEDRT instead of NDFRT when a MEDRT source of drug relations is being used.
    • VA Classes. VA classes which were available in NDF-RT are not included in MED-RT. However, we are providing the VA class information from an alternate source. Coverage of RxNorm drug products into VA classes are more comprehensive with the addition of a "has_VAClass_extended" relation which will provide associated drug product mappings into VA classes. Note that the VA class identifiers are changed from the NDF-RT unique identifiers (NUIs) to the 5-digit VA class ids.

Changes to APIs

The NDF-RT API has been decomissioned.
There are no plans for development of a MED-RT API.

On June 4, 2018, the RxClass API and RxClass web application started using the MED-RT data. Impacts on RxClass API users are:
  • Specifying MeSH identifiers instead of NDF-RT identifiers for Chem and Disease class identification. Class ids are used in the following table for the SOAP functions and REST resources.

    SOAP Function
    (Deprecated.
    Will be terminated
    in January 2020)
    REST Resource Description
    findClassesById /class/byId Find the drug classes from a class identifier
    /similar Find similar class membership
    getClassContexts /classContext Get the class context
    getClassGraph,
    getClassGraphBySource
    /classGraph Get the class graph of ancestors
    getClassMembers /classMembers Get the drug members of a specified class
    getClassTree /classTree Get the descendents of a class
    getSimilarityInformation /similarInfo Get the similarity information between members of two classes

  • Specifying the source of drug-class relations. Users should change from using NDFRT to MEDRT. For VA classes, the source of drug-class relations changes from NDFRT to VA. NOTE: the API will change requests specifying NDFRT to MEDRT for an undetermined time after the transition to minimize the impact on the users. Source of drug-class relations are used in the following SOAP functions and REST resources.

    SOAP Function
    (Deprecated.
    Will be terminated
    in January 2020)
    REST Resource Description
    findSimilarClassesByClass /similar Find similar class membership
    findSimilarClassesByDrugList /similarByRxcuis Find similar classes from a list of RxNorm drug identifiers
    getClassByRxNormDrugId /class/byRxcui Get the classes of a specified drug identifier
    getClassByRxNormDrugName /class/byDrugName Get the classes of a specified drug name
    getClassMembers /classMembers Get the drug members of a specified class
    getSimilarityInformation /similarInfo Get the similarity information between members of two classes

Example
To find the drugs that "may_treat" chronic hepatitis B, the RESTful query using NDF-RT class id was:
  https://rxnav.nlm.nih.gov/REST/rxclass/classMembers?classId=N0000003953&relaSource=NDFRT&rela=may_treat
The new query uses the MeSH identifier and specifies MEDRT instead of NDFRT:
  https://rxnav.nlm.nih.gov/REST/rxclass/classMembers?classId=D019694&relaSource=MEDRT&rela=may_treat

For questions, comments or feedback about these resources, please contact us at RXNAVINFO@LIST.NIH.GOV.