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Rationale for the National Extension to the SNOMED CT Drug Model

The international content of SNOMED CT is, by definition globally applicable.  For the concept of “atrial fibrillation”, most clinicians will agree on what constitutes the diagnosis of atrial fibrillation and how the concept should be logically defined.  Therefore, wherever in the world a patient suffers from atrial fibrillation, there is a common understanding of what that is, and the SNOMED CT concept for "atrial fibrillation" can represent and reflect that.

But medicinal products are different.  Concepts Concepts in a Medicinal Product terminology can be divided into two types:

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SNOMED CT International Release contains concepts of the first type; those whose representation is both understandable internationally and whose use has international applicability (e.g. in support of medication information in international patient summaries, or for international pharmacovigilance). But clinical care within member nations requires both the first and the second type of representation for medicinal products ; therefore concepts of the second type have to be authored in the extension belonging to that nation (or organisation)whereby each country can express their medicinal products with their names and using their values for definitional attributes, and if required, to have additional attributes, in the way that fits with their regulation and their healthcare culture and practice.  To support authoring of concepts of this second type and through it to have direct connection to and use of the tools, rules and content of the international core to leverage the value of that (for example, to find equivalence extension and provide interoperability of patient’s medication information and to facilitate internationally authored decision support, the national extension model is provided.  

Purpose

This document depicts an extension concept model to describe the real or actual medicinal products (sometimes described as "branded products") available for use in a particular member nation.  The model is compatible with the international core model for Medicinal Products.  This compatibility means that, when classified using the appropriate tooling, the correct classification results should be achieved with concepts being fully defined wherever possible.  This document should therefore be read alongside the SNOMED CT Medicinal Product Model Specification which describes the classes of concepts present in the international release.

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In all of the above, a reliable source of information for all the definitional attributes will be required; this may be challenging for unlicensed medicines and even for some "over the counter" medicines.

One thing that may It can be helpful in when considering setting the boundary for inclusion of products in the national extension, is if the national prescribing use case is in scope is , to include those products that can be 'legally supplied'; in most healthcare cultures, compounded products, unlicensed and investigational products can be legally supplied to patients provided the terms and conditions of the jurisdiction are fulfilled.  In addition, The scope setting will also need to bear in mind how to respond to the changes in the availability of products over time and the use case(s) for historic information for products that are no longer available in the supply chain.  The principles for the status of the terminology concepts themselves should be as in the core (i.e. active - intended for terminology use; inactive - not intended for terminology use); the implications of this in terms of use cases for active supply of medicines must also be considered.

This specification does not propose a model for the types of additional information that may be a useful part of a national medicinal product terminology, such as product availability or pricing. That is a matter for each jurisdiction. The principles for the status of the terminology concepts themselves should be as in the core (i.e. active - intended for terminology use; inactive - not intended for terminology use). 

Audience

This document is written primarily for those responsible for the development and maintenance of a (national) Medicinal Product terminology within a member nation or other organisation that is managed as a module within a SNOMED CT extension.
It will also be of value to those who have a (national) Medicinal Product terminology that is not managed as a module within a SNOMED CT extension, but who wish to provide a mapping from concepts in their Medicinal Product terminology to concepts in SNOMED CT International Release Medicinal Product hierarchy in order to harness the benefits of the rich international clinical terminology.