SNOMED CT Drug Model
The Two-Layer Model
The SNOMED CT Drug Model provides a comprehensive framework for representing medicinal products across healthcare systems. It is composed of two complementary components:
the SNOMED CT International Drug Model, which defines medicinal products in a jurisdiction-independent and clinically focused manner
the SNOMED CT Drug Extension Model, which represents real-world medicinal products authorized and available within specific jurisdictions
Together, these components support consistent representation of medicines across clinical, operational, and regulatory workflows, while enabling interoperability across systems and countries.
International Drug Model (Clinical Foundation)
The international model provides the clinical definition of medicinal products, focusing on characteristics such as:
active ingredient(s)
dose form
strength
It defines a set of concept classes that represent medicines at increasing levels of detail:
Medicinal Product (MP) – ingredient only
Medicinal Product Form (MPF) – ingredient + dose form
Clinical Drug (CD) – ingredient + dose form + strength
These concepts are:
independent of brand and packaging
consistent across jurisdictions
used for clinical decision support, prescribing, and analytics
Examples:
Product containing amoxicillin (MP)
Product containing amoxicillin in oral capsule dose form (MPF)
Product containing precisely amoxicillin 500 mg oral capsule (CD)
Drug Extension Model (Real-World Representation)
The drug extension model builds on the international model to represent actual medicinal products available in a country, including product identity and packaging.
It introduces additional concept classes:
Real Clinical Drug (RCD) – a specific authorized product
Clinical Drug Package (CDP) – a generic packaged form
Real Clinical Drug Package (RPCD) – a specific packaged product
These concepts are required for workflows that involve real products rather than abstract clinical definitions, such as:
dispensing and administration
inventory and supply chain management
reimbursement and regulatory processes
Examples:
Brand X amoxicillin 500 mg oral capsule (RCD)
Amoxicillin 500 mg oral capsule box of 24 (CDP)
Brand X amoxicillin 500 mg oral capsule box of 24 (RPCD)
How the Models Work Together
The international and extension models form a single, integrated structure, where extension concepts build directly on international concepts.
This structure reflects two complementary perspectives:
a clinical perspective, which defines what the medicine is
a real-world perspective, which defines how the medicine is supplied and identified
A Framework Based on Increasing Specificity
The SNOMED CT Drug Model can be understood as a progression from abstract to concrete representations:
MP – What substance is involved?
MPF – In what form is it administered?
CD – What is the precise clinical definition (including strength)?
RCD – Which specific product is used?
RPCD – Which specific packaged product is supplied?
In parallel:
CDP represents packaging at a generic level, without reference to a specific product
This layered approach allows systems to select the appropriate level of detail depending on the use case.
Attribute-Based Modeling (Conceptual View)
The model is based on a structured set of characteristics that define medicinal products. At a high level:
the international model defines clinical characteristics
the extension model adds product identity and packaging characteristics
This separation ensures that:
clinical meaning remains consistent across all products
real-world products can be represented without redefining clinical concepts
systems can move between levels (e.g. from product to ingredient) for aggregation and analysis
Why This Model Matters
By combining a shared international foundation with flexible national extensions, the SNOMED CT Drug Model enables:
consistent representation of medicines across systems
safe and precise clinical workflows
accurate identification of real-world products
interoperability across jurisdictions
It allows healthcare systems to represent both:
what a medicine is (clinical definition)
what product is used in practice (real-world product and packaging)
Summary of Drug Model Levels
For clarity, the SNOMED CT drug model distinguishes several levels of abstraction. Each level supports different clinical or administrative workflows.
MP (Medicinal Product)
Drug defined by active ingredient(s) only
Product containing amoxicillin
MPF (Medicinal Product Form)
Drug defined by ingredient and dose form
Product containing amoxicillin in oral capsule dose form
CD (Clinical Drug)
Drug defined by ingredient, strength, and dose form
Amoxicillin 500 mg oral capsule
RCD (Real Clinical Drug)
Authorized or branded medicinal product
BrandX amoxicillin 500 mg capsule
CDP (Clinical Drug Package)
Generic description of package
Amoxicillin 500 mg capsule box of 24
RPCD (Real Clinical Drug Package)
Actual packaged product available in supply chain
Brand X amoxicillin 500 mg capsule box of 24