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Model Overview

The diagram below shows the concept classes for the extension model with , and the related to, the concept classes in from the international release medicinal product model for medicinal products.   No role or grouper concept classes that are classes (i.e. parents of the the international Medicinal Product (MP) class in the international release are ) are shown in the diagram; it . It is expected that all grouping classes - (based on substance structure, disposition and therapeutic role - ) will be inherited from the international release.    For For all of the classes of in the national drug extension model for representation of medicinal products , the closed world view is applied; products applies. Products are defined using only the active ingredient substances, as authorised by the regulatory agency in the particular jurisdiction of use; packs . Packs are defined using only the clinical drug concepts that they are composed of (contain) (see also section 8 below).

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In the diagram, the MP classes are shown in shades of blue, the MPF classes in shades of yellow, the CD classes in shades of green and the PCD classes in shades of orange; the concepts represent the real world medicinal products available within a nation and described within that extension are shown in the brighter shades.

Classes of National Drug Extension Model

The five concept classes of the international release are shown on the left hand side in their three levels or groups (MP, MPF and CD), with their two representations - the "containing" and the "only" - of the open and closed world views respectively.  The sixth and optional class of MP Precisely is also shown, as that class may be used in a national extension model if required.  Definitions, descriptions and examples of the five concepts in these classes can be found in the SNOMED CT Medicinal Product Model Specification.  

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Definitions and detailed descriptions of the extension classes are given in the sections below this model introduction.

Implementation options

Extensions may wish to populate and use all of the classes described in the model, or they may wish to use only a subset; it is envisaged that the Clinical Drug class from the international core will be foundational, associated with the Real Clinical Drug in a national extension, but all others may be considered optional for implementation.

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All authored concepts should classify correctly despite the absence of some intermediary classes, provided that they have been modelled according to the SNOMED International standards, that is using the proximal primitive parent and the relevant attributes for the concept class.

Class Relationships

The model uses the standard generalisation/specialisation relationship between the mirrored "real" classes of the national extension and their abstract classes in the international core.   It also uses a partitive relationship, shown in the diagram as the specialised composition relationship (the 'live together, die together' relationship), between the Clinical Drug and Packaged Clinical Drug classes, indicating that the Packaged Drug classes are "composed of" concepts that are themselves Clinical Drugs.  This is reflected in the "contains clinical drug" attribute that is part of the logical definition of a Packaged Clinical Drug.   The composition relationship is particularly appropriate for those packaged medicinal products that contain more than one clinical drug (often referred to as "kit products"). The combination of the usual SNOMED CT generalisation relationship and partitive relationship is manageable within the SNOMED CT tooling and will be applicable for description of other types of product concepts within the overall scope of SNOMED CT such as medical devices, which are often composed of more than one type of entity (e.g. drug eluting stents). The use of the composition relationship between Clinical Drugs and Packaged Clinical Drugs means that if implementations wish to display Packaged Clinical Drugs with a direct relationship to the Clinical Drugs that they contain (as in "under" them in a hierarchical display) nd they wish to transfer information such as the therapeutic role from the Clinical Drug to the Packaged Clinical Drug that they are related to, this composition relationship and the 'contains clinical drug' attribute must to be used to facilitate that.  

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The relationships in the diagram are shown only in terms of their semantics; no cardinality is given. National extensions may populate those classes for which they have use cases; for example, if a nation has no requirement for the Real Medicinal Product class, it does not have to be populated.

Relationship between

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international

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and

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extension content

The international core content of SNOMED CT will provide all the attribute relationships (see detail below) needed to define medicinal product concepts in a national extension. These will be suitably defined according to SNOMED machine-readable concept model (MRCM) principles and available for use in the tooling. The concepts to provide the values for the product name and supplier cannot be present in the International edition as these do not have international applicability or even international uniqueness (especially for product name).  This specification therefore cannot provide ranges for these attributes; the supertype concepts are available (774167006 | Product name (product name) | and 774164004 | Supplier (supplier) |) to support extension authoring.

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