Drug Domain - OHDSI/Vocabulary-v5.0 GitHub Wiki

The drug exposure domain concepts capture records about the utilization of a Drug when ingested or otherwise introduced into the body. A Drug is a biochemical substance formulated in such a way that when administered to a Person it will exert a certain physiological or biochemical effect. The following products are not considered Drugs, but Devices:

• Diagnostic radiopharmaceuticals.
• Contrast material for imaging (barium sulfate, gadolinium, etc.).
• Nutritional products and supplements, including infant feeding. In reality that results in the slightly arbitrary and in some cases difficult to ascertain situation that solutions of salts are Drugs (hydrating patients and maintaining ionic balance), while the addition of nutrients such as glucose or vitamins makes them devices (feeding patients).
• Parenteral nutrition (aminoacids and/or lipid mixes).
• Solution for dialysis, catheter maintenance etc.
• Products directly derived from blood (erythrocytes, plasma, serum, thrombocytes), while immune globin or albumin preparations, monoclonal antibodies, coagulation factors and homeopathy derived from blood are Drugs.
• Transplants of any kind.
• Artificial saliva, artificial tears, and lubricants.
• Non-medicated cosmetics (creams, ointments, soaps, deodorants, shampoos), including SPF sunscreens.
• Glucometric strips, needles, tubes with anticoagulants, etc.
• Surgical materials like bone cement.
• Hemostatics materials (cellulose, flour, collagen, etc.).
• Disinfectants for inert surfaces.

Devices that contain drug substances (e.g. bone cement with antibiotics) are considered Devices, but should obtain additional mapping to the Drug Domain concepts.

Drug domain Concepts should be used in the drug_concept_id of the DRUG_EXPOSURE the DRUG_ERA and the DOSE_ERA (both only at the Ingredient level) tables, or in the value_as_concept_id field of the OBSERVATION or MEASUREMENT table (e.g. for Measurements like “Plasma level”).

The Drug Domain consists of Source Concepts (below the horizontal line), Drugs (Standard Concepts) and Classifications (Classification Concepts). As usual, Source Concepts are non-Standard Concepts that are used as coding schemes in various databases. As such, they are mapped to Standard Concepts.

Standard Concepts are based on the RxNorm and RxNorm Extension vocabularies. All Standard RxNorm and RxNorm Extension Concepts are used in the drug_concept_id fields.

RxNorm is the foundation for the combined Domain space. All valid RxNorm Concepts (invalid_reason is null) are used as Standard Concepts. However, RxNorm only contains Drug Concepts for products sold in the United States. All Concepts derived from international products are available in the RxNorm Extension vocabulary. Apart from the different vocabulary_id, both RxNorm and RxNorm Extension form a combined Concept space with identical rules for relationships and Concept Ancestry.

RxNorm and RxNorm Extension Concepts are hierarchical. Therefore the Concepts can also be used as Class Concepts: descendants of any Standard Concept in the CONCEPT_ANCESTOR table can expect to be a correct semantic match in a query. For example, a query for the descendants of an ingredient should turn up all drug products (Clinical Drug or Branded Drug) containing that ingredient.

On top of this combined RxNorm/RxNorm Extension Drug Domain are drug classification systems. These are derived from a variety of different vocabularies. Note: Any classification Concept may exist in different classifications, and therefore cannot be considered as unique. For example, NSAID Analgesics exist with very similar memberships as ETC, VA Class and SNOMED classes. Also note: Only ATC is defined for both RxNorm and RxNorm Extension drugs, and can therefore serve as a universal drug classification system for all drugs. The other classifications are defined for RxNorm, only, and future additions for subsets of RxNorm Extension.

Those for the Source and Classification Concepts are specific to the source vocabulary (see there). The Concept Classes for the Drug Concepts are based on a subset of RxNorm Term Types:

Term Type	Name	Concept Class
IN	Ingredient	Ingredient
PIN	Precise Ingredient	Ingredient (standard_concept = NULL)
MIN	Multiple Ingredients	Not implemented
BN	Brand Name	Brand Name
SCDC	Semantic Clinical Drug Component	Clinical Drug Component
SCDF	Semantic Clinical Drug Form	Clinical Drug Form
SCDG	Semantic Clinical Dose Form Group	Not implemented
SCD	Semantic Clinical Drug	Clinical Drug or Quantified Clinical Drug
SBDC	Semantic Branded Drug Component	Branded Drug Component
SBDF	Semantic Branded Drug Form	Branded Drug Form
SBDG	Semantic Branded Dose Form Group	Not implemented
SBD	Semantic Branded Drug	Branded Drug or Quantified Branded Drug
GPCK	Generic Pack	Clinical Pack
BPCK	Brand Name Pack	Branded Pack
DF	Dose Form	Dose Form
DFG	Dose Form Group	Not implemented
PSN	Prescribable Name	Not implemented
SY	Synonym	Implemented in the CONCEPT_SYNONYM table
TMSY	Tall Man Lettering Synonym	Not implemented
ET	Dose Form Entry Term	Not implemented

Concepts of the Concept Classses “Clinical Drug” and “Branded Drug” (SCD and SBD) of liquid formulations have their drug strength provided as concentrations, with or without the total quantity provided. That means, many of them exist in pairs. RxNorm does not represent this distinction using different Term Types, however, we defined additional Concept Classes “Quantified Clinical Drug” and “Quantified Branded Drug” for those drugs where a quantity factor is provided.

In addition to the RxNorm-derived Concept Classes, international coding schemes break drugs down according to their package or box size. This is due to the fact that prescription drugs are generally sold as prepackaged products, while most prescription drugs in the US get packaged at the time of the prescription filling in the pharmacy. Note, that these boxes are different from the RxNorm packs. Packs represent the smallest unit of drug product combinations, while boxes define the total amount of units sold as a product. In addition to boxes, international coding schemes also distinguish products of different manufacturers or resellers (suppliers). To make those coding schemes work seamlessly with the RxNorm system, additional Concept Classes were defined in the RxNorm Extension vocabulary:

Vocab	Name	Ingredient	Drug strength	Dose form	Brand name	Quantity factor	Box size	Pack content	Supplier
RxNorm	Ingredient	x
	Clinical Drug Component	x	x
	Clinical Drug Form	x		x
	Clinical Drug	x	x	x
	Branded Drug Component	x	x		x
	Branded Drug Form	x		x	x
	Branded Drug	x	x	x	x
	Clinical Pack	x						x
	Branded Pack	x			x			x
Rxnorm (not explicit)	Quantified Clinical Drug	x	x	x		x
	Quantified Branded Drug	x	x	x	x	x
RxNorm Extension	Clinical Drug Box	x	x	x			x
	Branded Drug Box	x	x	x	x		x
	Quantified Clinical Box	x	x	x		x	x
	Quantified Branded Box	x	x	x	x	x	x
	Clinical Pack Box	x	x	x			x
	Branded Pack Box	x	x	x	x		x
	Marketed Product	x	x	x	optional	optional	optional	optional	x

This system of Concept Classes is fully normalized. I.e. that for each defined, say, Branded Drug there are the equivalent Clinical Drug, Clinical Drug Component, Branded Drug Component, Clinical Drug Form and Branded Drug Form available. For combination drugs with several Ingredients equivalent combinations are defined in the same manner. Note that the latter is not true for Clinical Drug Components. These only exist as single-ingredient Concepts. The reason for this is not discussed in the technical documentation by RxNorm. Ingredients are only defined as single Ingredients, RxNorm's MIN (Multiple Ingredients) are not implemented.

As usual, all Source Concepts are mapped to the RxNorm or RxNorm Extension Concepts. The mapping is either constructed from the vocabulary source and in some cases curated by the vocabulary team. Generally, mappings are between equivalent Concept Classes, and if possible to Clinical or Branded Drugs, or more detailed Concept Classes further down in the hierarchy. However, in some cases this is not possible (e.g. when mapping Procedure Drugs) or if insufficient information is known about a Source Concept, at which point a more general Concept can be used. Such non-equivalent mappings are carried out as following:

• One-to-many mappings to Ingredients or Clinical Drug Components
• One-to-one mappings to all other Concept Classes

The internal relationships between Drug Concepts are derived from RxNorm relationships and extended to cover the additional Concept Classes of the RxNorm Extension vocabulary (“Drug” without any attribute means either “Clinical” or “Branded”):

Source	Original name	relatinship_id	Connecting Concept Classes
RxNorm	consists_of	Consists of	Drug or Quantified Drug and Drug Component
	constitutes	Constitutes	Drug Component and Drug or Quantified Drug
	contained_in	Contained in	Drug or Quantified Drug and Pack
	contains	Contains	Pack and Drug or Quantified Drug
	dose_form_of	RxNorm dose form of	Dose Form and Drug, Drug Form
	form_of	Form of	(Precise) Ingredient and Ingredient
	has_dose_form	RxNorm has dose form	Drug, Drug Form and Dose Form
	has_form	Has form	Ingredient and (Precise) Ingredient
	has_ingredient	RxNorm has ing	Clinical Drug Form/Component and Ingredient, and Branded Drug Form/Component and Brand Name. Not implemented between Branded Drug and Brand Name
	has_precise_ingredient	Has precise ing	Brand Name/Clinical Drug Component and (Precise) Ingredient
	has_quantified_form	Has quantified form	Drug and Quantified Drug
	has_tradename	Has trade name	Clinical and Branded Concept Class equivalents
	has_tradename	Has brand name	Ingredient and Brand Name
	ingredient_of	RxNorm ing of	Ingredient and Clinical Drug Form/Component, and Brand Name and Branded Drug Form/Component. Not implemented between Branded Drug and Brand Name
	inverse_isa	RxNorm inverse is a	Drug Form and Drug
	isa	RxNorm is a	Drug and Drug Form
	precise_ingredient_of	Precise ing of	(Precise) Ingredient and Brand Name/Clinical Drug Component
	quantified_form_of	Quantified form of	Quantified Drug and Drug
	reformulated_to	Reformulated in	Brand Name and Brand Name (name changes)
	reformulation_of	Reformulation of	Brand Name and Brand Name (name changes)
	tradename_of	Trade Name of	Branded and Clinical Concept Class equivalents
	tradename_of	Brand name of	Brand Name and Ingredient
	-	Concept replaced by	Concepts in RXNATOMARCHIVE with merged_to_rxcui information
	-	Concept replaces	Concepts in RXNATOMARCHIVE with merged_to_rxcui information
RxNorm Extension	-	Available as box	Drug and Drug Box
	-	Box of	Drug Box and Drug
	-	Has marketed form	Drug and Marketed Product
	-	Marketed form of	Marketed Product and Drug
	-	Has supplier	Drug and Supplier
	-	Supplier of	Supplier and Drug

For a discussion of the relationships between Drugs and Classifications and within Classifications please see the individual vocabulary sections.

Drug Strength

The Drug Domain has an additional DRUG_STRENGTH table defining the strength of each ingredient. This is defined for all Drug Concept Classes except Ingredient, Clinical Drug Form and Branded Drug Form, Dose Form, Brand Name and Supplier.