In this section, we compare the different approaches used by EDQM and SNOMED CT to represent the meaning of pharmaceutical dose forms. This understanding was used to develop the principles for defining semantic matches between EDQM and SNOMED CT dose forms.

Source Terminology

EDQM Example

An example of the source terminology, ie EDQM pharmaceutical dose forms, is shown below:

EDQM Definitions and Comments

In addition to the name of the PDF concept, the text definition of the term important to understand its meaning.   BUT not every part of the definition can be considered for the semantic and for mapping. 

Local or systemic effect

In the concept below "to obtain a local effect" is stated.  The definition of a PDF (see above) is concerned with it being the thing that formulates or encapsulates or contains the active and inactive ingredient substances either at the point of supply (the manufactured dose form) or at the point of administration (the administrable dose form); there should be no consideration of what happens to the active substance(s) once the administration has been made and therefore no consideration of what or where their effect is.   It is not possible to state accurately for any one medicinal product whether its effect (either therapeutically desired or undesired) will be "local" or "systemic" based on its dose form; for example, there are oral tablets that have no systemic effect (e.g. nystatin).  Therefore, if "for local effect" (or "for systemic effect") is part of either the definition or the comment for an EDQM PDF concept, it will not be deemed part of the semantic of the concept for mapping.

But there may be useful information in the "Comment" section that may need to be considered for mapping:

Although the "Comment" section is primarily aimed as “implementation guidance” for marketing authorisation applicants to guide them when they are selecting a PDF to use for their product, it may give information that “clarifies” the definition, so is something to consider when making a mapping.  For example, sometimes, the "Comment" section will describe what the concept is NOT as well as what it is, which may be important when considering a mapping.  However, statements like “Sublingual sprays are excluded“ are guidance for manufacturers to avoid ambiguity when they are selecting dose forms for products, not statements about the intended site concept itself.  The intent is that “if the product is a sublingual spray, give it a sublingual spray dose form, DON’T give it a “oromucosal spray” dose form (just because the sublingual site “is part of” the oromucosal“) (C Jarvis 2021-10-21) THEREFORE this makes the EDQM “oromucosal” similar to the SNOMED CT “oromucosal” – both act as grouper concepts.  A 1..1 map can therefore be made between the oromucosal, sublingual and buccal concepts in EDQM and SNOMED CT without being concerned by these exclusion statements “altering” concept meaning.

EDQM 

Characteristic values

The characteristic values for a PDF should also be examined whilst remembering that currently, the attributes of a PDF concept in EDQM are NOT definitional for the concept.

Definitions for the various values that can be used in the characteristics can be found at:

https://www.edqm.eu/sites/default/files/standard_terms_internal_vocabularies_for_pharmaceutical_dose_forms.pdf

Prolonged release

The definition of "prolonged release" is clear that this is "achieved by a special formulation design and/or manufacturing method" - and therefore, by implication, not by the substance.  Therefore products containing substances like "haloperidol decanoate" or "insulin isophane" or "insulin zinc suspension" should not have prolonged release dose forms as it is the modification of the substance that makes its release longer than the unmodified or simply modified substance, not the dose form.

Target Terminology

SNOMED CT Meanings

In SNOMED CT, the fully specified name (FSN) ‘unambiguously’ represents the meaning of the concept.  In addition:

• For "defined" concepts: the set of defining relationships sufficiently represents the logical meaning of the FSN
• For "primitive" concepts: the set of relationships represents part of the logical meaning of the FSN (the totality of the meaning is captured in the FSN)

There are some text definitions, especially for primitive concepts used as attributes in the concept model.  For example, the "method of administration" attribute value concepts have a textual definition.

The (poly)hierarchy of concepts should reflect the relationships, which themselves represent the concept and therefore should be correct for the concept.

SNOMED CT PDFs are “qualifier values” because they are used as attributes in the medicinal product concept model, but they are still full concepts in their own right.   

SNOMED CT Example

An example of the source terminology, ie EDQM pharmaceutical dose forms, is shown below:

The parent (grouping) concept 736542009 | Pharmaceutical dose form (dose form) | has no attributes (and is therefore marked as “primitive”) but the child concepts - the PDF concepts themselves, have a concept model.

Example (stated view):

Although polyhierarchical, the SNOMED CT browser will display concepts in the inferred view in a hierarchy based on the intended site of the dose form, with a grouper concept acting as the parent:

Not all PDFs in SNOMED CT are “fully defined”.  Two concepts cannot share the same logical definition and both be fully (logically) defined, so there are currently some primitive PDFs that have to be child concepts of fully defined concepts because they have extra meaning in their FSN.  There ay also be some primitive siblings: