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.

Changes to APIs

The NDF-RT API will continue to be available until January 2, 2019. At that time the NDF-RT API will be 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:
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.