Concepts Representing a Substance or its Modifications

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 | 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 | 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 | Is modification of (attribute)| of 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 |Is 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)|

Dried gels have an |Is modification of (attribute)| relationship to the gel substance.

• For example, 768558006 |Dried aluminium hydroxide gel (substance)| has an |Is modification of (attribute)| relationship of |Algeldrate (substance)|.

In general, an |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 example,

• 715220007 |Tenofovir alafenamide (substance)|

• 89678001 |Cefuroxime axetil (substance)|

|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)|.

• When the potential target would have been a grouper concept.

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