SNOMED CT Editorial Guide

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Overview

The substance redesign project has made a number of decisions regarding the representation of a substance and its modifications.

  1. Modification indicates that the concept is a structural modification of another concept, where the intrinsic physicochemical properties of the substance do not change.
  2. The intrinsic physicochemical properties do not encompass non-intrinsic characteristics of a substance, such as toxicity, bioavailability, or extended release (in the case of medicinal products).
  3. Modification concepts that exist to group modifications or derivatives of a specific substance are not to be created.
  4. Metabolite groupers in the substances hierarchy are considered roles. No further concepts of this format will be created in the |Substance| hierarchy.  Existing concepts will only be retained where there is a specific requirement and will be modeled as a child of |Metabolite (substance)|. See Metabolites.
  5. Structural groupers that reference modifications as a chemical group will be retained. Where the structural group name also refers to a specific chemical, the grouper will be re-termed “Substance with X structure”.  See relative section Substance Groupers Based on Structure.
  6. There is no requirement to introduce a new semantic tag in order to distinguish concepts representing a substance or its modifications from any other type of concept in the |Substance| hierarchy.

Modeling

Semantic tag

(substance)

Definition status

Primitive

Attribute:

Is modification of

Range:  <105590001 |Substance (substance)|

Exemplar

The following illustrates the stated view of 125691000 |Sotalol hydrochloride (substance)|:


The following illustrates the inferred view for 125691000 |Sotalol hydrochloride (substance)|:

Guidelines for the use of 738774007 | Is modification of (attribute)|

Substances may have zero to many Is modification of attribute(s).

For example,

    • Morphine hydrochloride (substance)

For example,

    • Fluorothymidine (18-F) (substance)



Hydrates have an  738774007 | Is modification of (attribute)| relationship to the unspecified salt.

For example,

    • Caffeine hydrate (substance) IS MODIFICATION OF Caffeine (substance). 

This is the stated view:

This is the inferred view:

For example, 

    • Clindamycin hydrochloride monohydrate (substance) IS MODIFICATION OF Clindamycin hydrochloride (substance).  

        This is the stated view:


This is the inferred view:

For example, 

    • Calcium lactate pentahydrate (substance) IS MODIFICATION OF Calcium lactate (substance)

This is the stated and inferred view.


Anhydrous salts have an  738774007 | Is modification of (attribute)| relationship to the unspecified salt.

For example,

    • Theophylline anhydrous (substance) IS MODIFICATION OF Theophylline (substance).

This is the stated view:

This is the inferred view:

The salts are modeled with an  738774007 | Is modification of (attribute)| the acid substance.

For example,

    • Pamidronate monosodium (substance) IS MODIFICATION OF Pamidronic acid (substance). This is the stated and inferred view.


Liposomal preparations are modifications of the chemical substance.

For example,

    • Daunorubicin citrate liposome (substance)|


Pegylated substances are modeled with |s modification of (attribute)| generic substance, if such a substance has been made available.  Not all pegylated medicinal substances have a non-pegylated form, as the non-pegylated form may have been too immunogenic or too toxic.

       For example, 

    • 785674001 |Turoctocog alfa pegol (substance)|

       

Concepts specifying a particular physical form (e.g., micronized, macrocrystal, microsphere) should have a parent concept that relates to the structure of the substance and also an |Is modification of (attribute)| relationship to the unspecified substance concept.

For example, 

    • 414246008 |Fenofibrate micronized (substance)|

Grouper concepts should not be targets of an  738774007 | Is modification of (attribute)| relationship.

In general, an  738774007 | Is modification of (attribute)| is not applicable to prodrugs.  This is because there is no requirement for the |Has active ingredient (attribute)| of medicinal products containing prodrug substances to use any relationship to the active substance to manage relationships within the medicinal product hierarchy. 

For example, aspirin is not generally considered a modification of the substance salicylic acid.

When a prodrug is an esterified form of substance, there should be an  738774007 | Is modification of (attribute)| relationship between the substance and its esterified form.

For exemplar,

    • 715220007 |Tenofovir alafenamide (substance)|
    • 89678001 |Cefuroxime axetil (substance)|

738774007 | Is modification of (attribute)| is not applicable:

  • Between a glycan and its glycoconjugate.
    • For example, 259289005 |Trimethylene glycol (substance)| is not a modification of 52086008 |Glycol (substance)|.
  • To genetic engineering process variations (e.g., Somatropin(epr), Somatropin(rbe), or Somatropin(rmc)), as SNOMED CT does not generally differentiate substances based on production process.
  • Between a chemical element and its salt.
    • For example, 387307005 |Calcium carbonate (substance)| is not a modification of |Calcium (substance)|.


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