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Unified Medical Language System® (UMLS®)

2011AA FDA National Drug Code Directory Source Information

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The U.S. National Library of Medicine (NLM) produces the Metathesaurus FDA National Drug Code Directory (MTHFDA), which is based on the Food and Drug Administration (FDA) National Drug Code (NDC) Directory. The NDC Directory is published by the U.S. FDA Center for Drug Evaluation and Research.

Concept names with this source abbreviation were created by NLM to provide contextual information for the FDA NDC Directory terms.

The current edition of the NDC Directory is limited to prescription drugs and insulin products that have been manufactured, prepared, propagated, compounded, or processed by registered establishments for commercial distribution. The products have been listed in accordance with the Drug Listing Act and regulatory provisions concerning the submission of drug product information to FDA.

Metathesaurus Scope
MTHFDA includes only clinical drugs and NDC codes.

MTHFDA has approximately 85,381 clinical drugs.

Update Frequency
The NDC Directory is updated semimonthly.

Metathesaurus Update Frequency
MTHFDA is updated in each Metathesaurus release as part of RxNorm.

Sites Consulted

  1. Center for Drug Evaluation and Research. Rockville (MD): Food and Drug Administration (US). The National Drug Code Directory; [updated 2010 Nov 18; cited 2010 Nov 20]. Available from:

Last Reviewed: May 12, 2011