I’m not going to dwell on the horribles of RRF, the custom UMLS/RXNORM release format, but let me call out one …

104419|ENG||||||2701592|2701592|104419||RXNORM|SBD|104419|24 HR Felodipine 5 MG Extended ...
104419|ENG||||||2701593|2701593|104419||RXNORM|SY|104419|24 HR Plendil 5 MG Extended ...

It doesn’t jump out but find TTY, the lynchpin of the RRF format – each element of the normalized form can be identified by the value of the TTY [Term Type] field. It’s the column with values SBD which means Semantic branded drug and SY which means Synonym. In the first row, TTY holds the type of a concept (Semantic Branded Drug) but in the next, it holds the type of the label of that concept (Synonym). One field, two different uses. Processors beware!

The above looks like this in RDF …

rxnorm:104419 skos:broader rxnorm:SBD ;
              skos:prefLabel "24 HR Felodipine 5 MG Extended Release Tablet [Plendil]" ;
              skos:altLabel "24 HR Plendil 5 MG Extended Release Tablet" ;
              rxnorm:quantified_form_of rxnorm:844417 ;
              rxnorm:has_ingredient rxnorm: 203016;
              rxnorm:has_dose_form rxnorm:316945 ;
              rxnorm:tradename_of rxnorm:402696 ;
              ...

Much better I think you’ll agree and, for the technical, quiet readable. And notice there are properties other than name and type, tradename and its ilk. While names and types of concepts come from the RRF concepts file, these started in the RRF relationships file. With RDF, everything about a concept ends up in one place. What’s more, this same format works for other vocabularies from ICD 9 to SNOMED. In scheme definition, custom specification formats can be banished. One size does fit all.

The RXNORM Overview comes with a list of example queries – it has you traversing the RRF data (or its SQL equivalent) but we’ll SPARQL our RDF instead …

SELECT ?concept
WHERE {?concept skos:prefLabel 'Amoxicillin'}

SELECT ?concept ?conceptLabel
WHERE {?concept skos:prefLabel ?conceptLabel ;
       rxnorm:form_of rxnorm:723}

SELECT ?concept ?conceptLabel
WHERE {?concept skos:prefLabel ?conceptLabel ;
       rxnorm:tradename_of rxnorm:723}

SELECT ?concept ?conceptLabel
WHERE {?concept skos:prefLabel ?conceptLabel ;
       rxnorm:has_ingredient rxnorm:723 ;
       skos:broader rxnorm:SCDC}

SELECT ?concept ?conceptLabel
WHERE {?concept skos:prefLabel ?conceptLabel ;
       rxnorm:has_ingredient rxnorm:723 ;
       skos:broader rxnorm:SCDF}

Oh, how easy it is when RXNORM (and SNOMED and …) become RDF! Shouldn’t they just come in RDF in the first place?