SubstanceDefinition — Pharmaceutical substance definition
The chemistry card for a pharmaceutical substance: structure, properties, regulatory codes, official names. Cornerstone of IDMP on the substance side.
Purpose of the resource
SubstanceDefinition represents a substance defined at the monograph level: its chemical structure (SMILES, InChI, molecular formula), molecular weight, official names (INN, USAN, BAN, JAN), regulatory identifiers (FDA UNII, EMA SMS), and all the properties characterising the substance before any pharmaceutical formulation.
To be distinguished from Substance, which describes a physical batch in stock (lot
23456, expiry 2027-12-31). SubstanceDefinition is a dictionary card; Substance is an inventory
object.
Key fields
| Field | Type | Cardinality | Role |
|---|---|---|---|
identifier | Identifier[] | 0..* | UNII, CAS, EC, EMA SMS. |
version | string | 0..1 | Definition version. |
status | CodeableConcept | 0..1 | Publication status. |
classification | CodeableConcept[] | 0..* | Classifications (mechanism of action, therapeutic class). |
domain | CodeableConcept | 0..1 | Domain (human, veterinary). |
grade | CodeableConcept[] | 0..* | Pharmaceutical grade (USP, BP, Ph.Eur.). |
description | markdown | 0..1 | Free-text description. |
informationSource | Reference(Citation)[] | 0..* | Documentary sources. |
manufacturer | Reference(Organization)[] | 0..* | Known manufacturers. |
supplier | Reference(Organization)[] | 0..* | Known suppliers. |
moiety | BackboneElement[] | 0..* | Chemically active parts. |
characterization | BackboneElement[] | 0..* | Physical characterisations. |
property | BackboneElement[] | 0..* | Properties (solubility, pKa, melting point). |
molecularWeight | BackboneElement[] | 0..* | Molecular weight. |
structure | BackboneElement | 0..1 | Structural representation (SMILES, InChI). |
code | BackboneElement[] | 0..* | External codes. |
name | BackboneElement[] | 0..* | Names (INN, USAN, BAN, JAN, brands). |
relationship | BackboneElement[] | 0..* | Relationships between substances (salt, ester, isomer). |
sourceMaterial | BackboneElement | 0..1 | Source material (biological origin). |
JSON example
{
"resourceType": "SubstanceDefinition",
"id": "example-acetaminophen",
"identifier": [{
"system": "http://fdasis.nlm.nih.gov",
"value": "362O9ITL9D"
}],
"status": {
"coding": [{
"system": "http://terminology.hl7.org/CodeSystem/publication-status",
"code": "active"
}]
},
"classification": [{
"coding": [{
"system": "http://example.org/substance-classification",
"code": "analgesic"
}]
}],
"name": [{
"name": "Acetaminophen",
"type": {
"coding": [{
"system": "http://terminology.hl7.org/CodeSystem/substance-name-type",
"code": "INN"
}]
},
"preferred": true
}],
"molecularWeight": [{
"method": {
"coding": [{
"system": "http://example.org/molecular-weight-method",
"code": "computed"
}]
},
"amount": {
"value": 151.16,
"unit": "g/mol"
}
}]
}Linkage with ISO 11238
ISO 11238 is the IDMP standard dedicated to the normative description of substances. SubstanceDefinition carries a direct mapping of ISO elements:
moiety↔ Substance Moiety.structure↔ Structural Representation.name↔ Substance Names.relationship↔ Substance Relationships.sourceMaterial↔ Source Material (biological origins).
Common pitfalls
- Non-canonical SMILES — use a canonical SMILES for deduplication.
- Missing UNII — without UNII, the substance is not FDA-tracked.
- Confusion with Substance — no batch, no expiry date here.
Related resources
- Substance — physical instance.
- MedicationKnowledge — drug base.
- ManufacturedItemDefinition — manufactured unit.
- Medication.
- FHIR R5 hub.