I'm currently operating under the assumption that any two NDCs with the same RxCUI value are pharmaceutical equivalents. Hopefully that's correct.

When querying the NDC data from OpenFDA, I noticed that for any given product NDC, there can be multiple RxCUI values. My understanding of the RxCUI value is very limited, but I would like to get a one-to-one relationship for RxCUI to package NDC. Is this possible?


Yes, your assumption about pharmaceutical equivalency is correct.

The relationship between RxCUI and Package NDC is actually many-to-many. For example, this cold & flu relief drug has multiple rxcui values -- 1086991, 1110988, 1801964 -- and these rxcui values correspond to other NDC drugs, too (here is an example). So I am not sure building a one-to-one relationship would be reasonable.

  • Am I not understanding this paragraph (section 7.0) correctly? "...a single NDC code should properly be associated with only a single RxCUI, though a single RxCUI can have multiple NDCs...". Also, as an example, in OpenFDA, NDC 50102-300-13 has three RxCUI values, but in RXNSAT.RRF, it only has the last of the three values. Is it possible that the last value is the only one that's still currently relevant, and perhaps the ones before that are historical and now retired?
    – Travesty3
    Nov 16 '20 at 20:04

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