Cool Technology for Pharmacy

My Cool Technology for Pharmacy this week strays a little from my normal hardware and software approach and focuses on the concept of RxNorm. The reason for this deviation is simple; my ignorance of RxNorm was never more evident than during my time at ASHP Midyear this week. I don’t like it when I lack understanding of what people are talking about, and this happened on a couple of occasions during discussions involving RxNorm. This was especially true during a presentation by Dr. Usha Desiraju of First DataBank. Dr. Desiraju’s presentation focused on the use of RxNorm and interoperability.

So I was forced to do a little reading. The entire idea seems simple enough, but like many good ideas implementation and acceptance is a little like trying to push the wrong end of two magnets together. In the simplest terms I can muster, think of RxNorm as a standardized language used to identify each unique medication across multiple systems.

According to the National Library of Medicine (NLM) :

RxNorm is a standardized nomenclature for clinical drugs and drug delivery devices, is produced by the National Library of Medicine (NLM). In this context, a clinical drug is a pharmaceutical product given to (or taken by) a patient with a therapeutic or diagnostic intent. A drug delivery device is a pack that contains multiple clinical drugs or clinical drugs designed to be administered in a specified sequence. In RxNorm, the name of a clinical drug combines its ingredients, strengths, and/or form.

While ingredient and strength have straightforward meanings, clarification of what is meant by form may be needed. In RxNorm, the form is the physical form in which the drug is administered or is specified to be administered in a prescription or order. The RxNorm clinical drug name does not refer to the size of the package, the form in which the product was manufactured, its form when it arrived at the dispensary or the intended route.

RxNorm’s standard names for clinical drugs and drug delivery devices are connected to the varying names of drugs present in many different controlled vocabularies within the Unified Medical Language System (UMLS) Metathesaurus, including those in commercially available drug information sources. These connections are intended to facilitate interoperability among the computerized systems that record or process data dealing with clinical drugs.

Purpose of RxNorm
Because every drug information system that is commercially available today follows somewhat different naming conventions, a standardized nomenclature is needed for the smooth exchange of information, not only between organizations, but even within the same organization. For example, a hospital may use one system for ordering and another for inventory management. Still another system might be used to record dose adjustments or to check drug interactions. Several cooperating hospitals might have different systems, and find their data incomparable.

A standardized nomenclature that relates itself to terms from other sources can serve as a means for determining when names from different source vocabularies are synonymous (at an appropriate level of abstraction). The goal of RxNorm is to allow various systems using different drug nomenclatures to share data efficiently at the appropriate level of abstraction.
A Simple Idea Implemented Rigorously

RxNorm is organized around normalized names for clinical drugs and drug delivery devices. These names contain information on ingredients, strengths, and dose forms. In the case of the drug delivery devices, the quantity is also listed. For example:

For generic drug name-
Acetaminophen 500 MG Oral Tablet

For a branded drug name-
Acetaminophen 500 MG Oral Tablet [Tylenol]

For a generic drug pack-
{5 (Aspirin 325 MG Oral Tablet) / 5 (Pravastatin 20 MG Oral Tablet) } Pack

For a branded drug pack-
{30 (Aspirin 325 MG Oral Tablet) / 30 (Pravastatin 20 MG Oral Tablet [Pravachol]) } Pack [Pravigard 325/20]

Within RxNorm, generic and branded normalized forms are related to each other and to the names of their individual components by a well-defined set of named relationships. Thus, Acetaminophen 500 MG Oral Tablet is related to Acetaminophen 500 MG Oral Tablet [Tylenol], and both have relationships to Acetaminophen, Acetaminophen 500 MG, and Oral Tablet. Within the UMLS Metathesaurus, Acetaminophen 500 MG Oral Tablet and Acetaminophen 500 MG Oral Tablet [Tylenol] will each be linked to different names that are used for these entities in other vocabularies.

Resources for RxNorm

There is a nice introductory video (“screen cast”) on “Understanding RxNorm” by Charlie Harp at

Pharmacoinformatics RSS Feed from John Poikonen’s Public Evernote repository.

National Library of Medicine Unified Medical Language System (UMLS)

RxNorm overview at the National Library of Medicine.

RxNav ( – a browser for RxNorm. See the screen shot below of a search I did for acetazolamide using RxNav.


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