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 concepts that exist to group modifications or derivatives of a specific substance not be created.
2. Metabolite groupers in the substances hierarchy are considered roles. No further concepts of this format will be created in the substances hierarchy. Existing concepts will only be retained where there is a specific requirement and will be modeled as a child of the concept Metabolite (substance). See relative section elsewhere in this document.
3. 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 elsewhere in this document.
4. 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 using the IS Modification attribute (stated view)

Exemplar

The following illustrates the stated view

The following illustrates the inferred view for concepts that are a modification.

Guidelines for the use of the IS Modification attribute with Examples

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

For example, Morphine hydrochloride (substance)

For example, Fluorothymidine (18-F) (substance)

For example, Doxepin hydrochloride (substance)

Hydrates have a IS MODIFICATION OF 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 a IS MODIFICATION 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 IS Modification 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 should be 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.

Grouper concepts should not be targets of an "Is_modification” relationship.

In general, an |Is modification of (attribute)| is not applicable to prodrugs. For example, aspirin is not generally considered as a modification of the substance salicylic acid. 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. 

"Is_modification” relationship is not applicable between a glycan and its glycoconjugate. Exemplar: 259289005 |Trimethylene glycol (substance)| will not be a modification of 52086008 |Glycol (substance)|.

"Is_modification” relationship is not applicable 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.

"Is_modification” relationship is not applicable between a chemical element and its salt. Exemplar: 387307005 | Calcium carbonate (substance) | is not a modification of |Calcium (substance)|.