Vocab. RXNORM_EXTENSION

RxNorm Extension

RxNorm Extension is an OHDSI resource to represent international drugs in a structure adapted from RxNorm. This describes the process, rules and resulting structure of incorporating international drug vocabularies into an overall RxNorm-like system, called RxNorm Extension.

Drug vocabularies contain drug products and their components. Only about a third of these products are identical in the drug markets of individual countries or jurisdictions of a drug marketing approval agency. Even if the active ingredients are the same, they can differ in their Drug Strengths, Drug Forms, Brand Names, package sizes and manufacturers or distributors.

Therefore, these vocabularies need to be incorporated into the existing Drug Domain in such a way that all existing drugs and their components are correctly mapped, and the missing ones added as new concepts. This includes a life cycle for each Concept, allowing to generation, deprecation and update over time.

The processing script that follows these instructions can be found here.

General structure

The Drug Domain should be organized in a hierarchical structure described in Drug Domain. This structure is based on RxNorm, which also forms the core of the content. RxNorm comprehensively describes the drug market in the United States. It may not contain products sold in the markets of other countries. It also does not contain US medical food or food supplement products.

This structure contains at a minimum (from bottom to top):

Concept Class	Composed of
Branded Drug	Ingredients, their strength, form, brand name
Clinical Drug	Ingredient, their strength, form
Branded Drug Form	Ingredient, form, brand name
Clinical Drug Form	Ingredient, form
Branded Drug Component	Ingredient, strength, brand name
Clinical Drug Component	Ingredient, strength
Dose Form	Form
Brand Name	Brand name
Ingredient	Ingredient
Drug Class	Drug class

It may optionally contain

Concept Class	Composed of
Marketed Product	Ingredients, their strength, form, supplier (brand name and box size are optional)
Quantified Branded Drug Box	Ingredients, their strength, form, brand name, size and box size
Quantified Clinical Drug Box	Ingredients, their strength, form, size and box size
Branded Drug Box	Ingredients, their strength, form, brand name and box size
Clinical Drug Box	Ingredients, their strength, form and box size
Quantified Branded Drug	Ingredients, their strength, form, brand name, size
Quantified Clinical Drug	Ingredients, their strength, form, size
Branded Pack	Branded Drugs, their number (box size is optional)
Clinical Pack	Clinical Drugs, their number (box size is optional)
Supplier	Supplier

Currently not supported are the following classes:

Concept Class	Composed of	Remarks
Precise Ingredient	Ingredient	Ingredient used instead; Precise Ingredients are mapped to Ingredients inside CONCEPT_RELATIONSHIP table
Multiple Ingredient	Ingredients	Single ingredients used instead
Dose Form Group	Dose Form	Explicit Dose Forms used instead; Dose Form Groups exist as Classification concepts and bear relation to standard concepts only inside native RxNorm vocabulary