Rationale for the National Drug Extension

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Model

The international content of SNOMED CT is, by definition, globally applicable.  For the concept of “atrial fibrillation”example, most clinicians will agree on what constitutes the a diagnosis of atrial fibrillation and how the this 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 in a Medicinal Product terminology can be divided into two types:

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1. Those concepts whose representation is abstract but which can be understood and used internationally (with sufficient language support)

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1. . These are described generically using their internationally recognised constituent parts, which are:  

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1. • Active ingredient substance(s) and basis of strength substances described (whenever possible) using their international non-proprietary names (INNs)

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1. • possible

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1. • Active ingredient strength(s), described using international standards and principles such as the RTO<PQ>

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1. • datatype (the ratio of physical quantities - see International Organization for Standards

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1. • , Health informatics — Harmonized data types for information interchange ISO 32090:2011)

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1. • and/or UCUM units of measure or their equivalent,

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1. • which in SNOMED CT is accomplished by using specific attributes for each of the numerator and denominator values

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1. • (represented as a concrete value) and units (represented as a SNOMED CT concept)

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1. • Pharmacopoeial / internationally defined dose forms

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1. • Pharmacopoeial / internationally defined units of presentation (when appropriate)

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1. Those concepts which describe real or actual products available for clinical use whose representation can only be fully described and understood within a jurisdiction, as they are governed by the regulations of that jurisdiction and produced by authorisation of a medicines regulatory agency responsible for that jurisdiction. This includes:

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1. • Authorised product names (which may be brand or trademarked names)

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1. • . A brand name in one jurisdiction may relate to a different product than the same brand name used in another jurisdiction

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1. • (although medicines regulatory agencies are trying to reduce this because of the safety issues it raises).

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1. • Proprietary dose forms, including those describing a timing component  (e.g. "caplets", "24-hour prolonged release tablets")

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1. • Additional characteristics in the product name such as

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1. • • Inclusion or exclusion of particular excipients with various roles ("strawberry flavour", "sugar-free")

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1. • • Target population groups ("for children")

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1. • • Indication for use ("cough and cold")

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1. • Packaging information
     • pack size
     • container description

International SNOMED CT International Release contains releases contain concepts of the first type; , i.e., 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 whereby to enable each country can to express their medicinal products with their names and using their values for definitional attributes names, their definitions, and if required, to have additional defining attributes , in the way that fits fit with their regulation and their healthcare culture and practice.   To support This national drug extension model is provided to support the authoring of drug 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

to enable the sharing of tools (e.g., drug authoring tools), rules (e.g., international decision support rules), and drug extension content (e.g., to support the interoperability of a patient's medication information, for cross-border dispensing with contraindication checking).

Use Cases for the National Drug Extension Model

National drug extensions have to support a variety of use cases; these can include any or all of:

• Prescribing medicines - such that medicinal products are described in sufficient detail that the next action in the process (either dispensing or administration) can identify the correct product to dispense/administer
• Dispensing
  • Reimbursement information
  • Supply chain management (including ordering of medicines for dispensing)
  • "Track and trace" including fraudulent medicines avoidance
• Administration
  • Closed loop medication systems
• Medication history/patient medication lists
• Linking to decision support
• Pharmacovigilance
• Secondary uses (clinical research, pharmacoepidiemiology)
• Supporting electronic data exchange for any or all of the above use cases (for both human users and for system users)

Purpose

This document specifies a drug extension concept model that can be used to represent This document depicts an extension concept model to describe the real or actual medicinal products (sometimes described referred to as "branded products") available for use in a particular member nation.  The country/territory. This 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.  extension concepts will be correctly placed alongside other concepts in the international Medicinal Product hierarchy. This document should therefore be read alongside together with the SNOMED CT Medicinal Product Model Specification, which describes the classes of concepts present in the SNOMED CT international releaseedition.

This document is a model specification, and as such, it does not describe in any detail the detailed rules and processes required to be adopted for population of populate a national terminology; some .  Some general principles are given, but exact processes are notand terming suggestions are provided.  These, and the terming guidelines for creation of fully specified names and additional description terms for the concepts that populate the additional model classes will need to be authored by national extensions, mindful of their own language, culture and practice considerations.  These descriptive terms may contain more information than that of the definitional attributes described in this specification: for example, some products may contain excipient information in their name - "without preservative" or "orange flavour", or target population information "for children"; all of this can be be reflected in the fully specified name for the relevant concept but would not be included in the value of the "product name attribute" - see section 10.1 below.  In addition, national extensions may wish to author a range of synonym terms, including user interface terms, to support direct implementation.  National extensions may wish to include the abstract class fully specified name within or after the fully specified name for the associated real product (for example including the full generic Clinical Drug name (either FSN or PT) in the Real Clinical Drug name: "AMOCAPS 250mg Freds Pharmaceuticals (amoxicillin 250mg oral capsules)").   However, when However, national extensions must be mindful of their own terming requirements when authoring synonym terms to support direct implementation. In situations where additional concepts for core classes of the international model are required in the national extension (e.g. MP, MPF (if required) , and CD) are authored in a national extension, the naming guidelines for the international release should be followed , (particularly for the FSN in particular.In this document, as generally, the words 'package' and 'pack' are synonymous; 'package' is the preferred term in the documentation, although 'pack' may be used especially when short text is required).

General principles for authoring SNOMED CT extension content can be found at 5.4.1 General Authoring Principles.

Scope

The scope of this concept model (as documented defined) is limited to medicinal products (pharmaceutical and biological); products that represent blood .  Blood products, foods, additives, and complementary medicines (including homoeopathic homeopathic products) are currently out of scope. Currently, vaccines, although   Vaccines are also out of scope (even though they are biological medicinal products, are also out of scope).

National extensions will have need to make decisions about the scope of their own medicinal product terminology as they and may require the representation of products that are beyond the international scope, and therefore may need to author, at a minimum, Clinical Drug concepts within their extension (for example . In these cases, it may be necessary to author Clinical Drug concepts (and their associated MP and MPFs) within the extension (e.g., to describe national pharmacopoeial formulations).  In addition, national extensions will need to set a scope for the range of medicinal products to be included; factors . Factors to consider compriseinclude:

• Licensed medicinal products (i.e., those with a valid authorisation within the jurisdiction of the extension)
  • This may or may not include those licensed for sale or supply without an order (prescription) from a healthcare professional, depending on scope; these .  These products are often known as "over the counter" medicines.
• Unlicensed medicinal products
  • Previously licensed medicinal products (- i.e. those that have, at some point in the last but which no longer hold , held a valid authorisation within the extension's jurisdiction of the extension); some , but which no longer do.  Some of these previously licensed products may continue to be available (e.g., via import (see next point below)
  • Medicinal products holding a valid authorisation in a different jurisdiction but , which are (regularly) used within the extension's jurisdiction of the extension by practitioners on at their own clinical responsibilitydiscretion
  • Medicinal products that are compounded according to recognised formulae; these . These are usually produced by authorised compounding units.
  • Investigational medicinal products (if and when good sources of this information become available through IDMP)

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

It can be helpful when considering setting the boundary for inclusion of products in the national extension , is (if the national prescribing use case is in scope), 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.  The scope will must 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 . 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 knowledge that may be a useful part of a national medicinal product terminologycatalogue, such as product availability or pricing. That is a matter for each jurisdiction. 

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 (national, regional or organisational) that is managed as a module within a SNOMED CT extension.
It   However, it will also be of value to those who have a an existing Medicinal Product terminology (national) Medicinal Product terminology that is not managed as a module within , regional or organisational) which may or may not be managed in a SNOMED CT extension, but who wish to provide develop a mapping from concepts in their own Medicinal Product terminology to concepts in a standardized SNOMED CT International Release Medicinal Product hierarchy in order representation to harness the interoperability benefits of the rich international clinical using a common concept model defined in a clinical reference terminology.