RxNav: A Semantic Navigation Tool for Clinical Drugs

The RxNorm project 1 aims at creating a consistent representa- tion for clinical drugs in the Unified Medical Language Sys- tem ® (UMLS ® ). A semantic normal form for a clinical drug, designed to represent the meaning of an expression typically seen in a practitioner's medication order, has been developed and is being created in the UMLS Metathesaurus ® . The long- term goal of this project is to establish a relationship for every concept in the Metathesaurus with semantic type Clinical Drug with one or more of these semantic normal forms. More precisely, there are two types of semantic normal form (SNF) concepts: one for drug components, consisting of an ingredient and a strength, and the other for the clinical formu- lation, consisting of at least one drug component and a dose form. The relationships among the various entities of the model have been defined and are illustrated in the example shown in Figure 1.