This guide provides practical guidance for implementing the SNOMED CT drug model for medicinal products. It explains how medicinal products are represented within the SNOMED CT Pharmaceutical and Biologic Product hierarchy, including the different levels of abstraction such as ingredient-based medicinal products, medicinal product forms, clinical drugs, and real clinical drugs.

The guide describes how the internationally consistent SNOMED CT drug model is used alongside National SNOMED CT Drug Extensions to represent jurisdiction-specific information such as authorized product names, packaging, and locally marketed medicines. It also outlines best practices developed through collaboration within the Drug Extension User Group (DEUG) and supports implementers, National Release Centers, and regulators in creating, maintaining, and using SNOMED CT drug concepts in clinical and administrative systems.

Model-Driven and Scalable Authoring

Drug extension content is not typically authored manually on a concept-by-concept basis. Instead, it is derived from existing national drug dictionaries using a structured and scalable process.

This approach is comparable to the development of terminologies such as LOINC, where content is generated based on combinations of well-defined attributes.

Process

Drug extension development involves several common challenges, including:

• Variations in ingredient representation across local dictionaries

• Limited granularity in source data (e.g. missing strength or form details)

• Rounding rules for strength normalization

• Non-normalized strength expressions, including numerator/denominator inconsistencies

Addressing these challenges requires careful normalization and alignment with the SNOMED CT concept model.

Terminology services provide the core infrastructure for accessing, querying, and validating SNOMED CT drug content. They enable systems to use the SNOMED CT Drug Model in a computable and scalable way, supporting both clinical workflows and analytical use cases.

A terminology service acts as the intermediary between:

• the RF2 terminology content (International + Drug Extension)

• the applications and APIs that consume drug data

Core Capabilities

A terminology service used for SNOMED CT drug content should support the following capabilities:

• Concept lookup

  Retrieve details of a concept (e.g. term, status, relationships)

• Hierarchy traversal

  Navigate parent–child relationships across the drug hierarchy (e.g. MP → CD → RCD)

• Subsumption testing

  Determine whether one concept is a subtype of another (e.g. whether a product contains a given ingredient)

• Value set expansion

  Generate a set of concepts based on defined criteria (e.g. all drugs containing a substance)

• Expression Constraint Language (ECL) execution

  Perform dynamic, logic-based queries over SNOMED CT content

These capabilities are essential to support:

• clinical decision support

• product selection and substitution

• reporting and analytics

• interoperability between systems

Terminology services are particularly important for the SNOMED CT Drug Model because they enable:

• navigation across abstraction levels

  (e.g. linking CD → RCD → RPCD)

• dynamic grouping of drugs

  (e.g. all products containing an ingredient)

• clinical reasoning

  (e.g. interaction checking, dose validation)

FHIR-based terminology services provide standardized APIs for accessing SNOMED CT content. These APIs enable consistent use of drug terminology across systems.

Key operations include:

• $expand

  Expands a value set into a list of SNOMED CT concepts

  (e.g. all drugs containing a specific ingredient)

• $validate-code

  Validates whether a code is valid within a given value set or system

  (e.g. checking if a selected drug is a valid Clinical Drug)

When implementing terminology services for drug content, systems should ensure:

• support for ECL queries involving attributes (ingredient, dose form, strength)

• efficient handling of large extension datasets

• alignment between terminology services and FHIR APIs

• consistent use of value sets across workflows

Because drug data is both hierarchical and highly structured, terminology services are not optional—they are a core dependency for safe and effective implementation of the SNOMED CT Drug Model.

Overall Consideration

Drug extensions introduce additional complexity compared to other SNOMED CT domains.

They are often aligned with national regulatory sources and pharmaceutical product registries, which may result in:

• more frequent updates

• changes in product availability

• variation in modeling granularity

Because extension content depends on the International Edition, updates to international content may require corresponding updates in the extension. For example:

• new substances or Clinical Drugs may become available

• existing extension concepts may need to be revised or aligned

• concepts created in extensions may later be promoted to the International Edition

Implementations must therefore support ongoing synchronization between international and extension content, ensuring that both layers remain semantically aligned.

In addition, systems should be prepared to handle situations where concepts move between modules (e.g. from extension to international), while preserving identifier continuity and mappings.

Deploying the SNOMED CT Drug Model requires a robust technical approach that supports:

• layered loading of international and extension content

• consistent version management and update processes

• handling of concept inactivation and replacement

• preservation of historical meaning

Because drug data is both clinically critical and operationally dynamic, terminology updates must be carefully managed to ensure that they are safely integrated into clinical workflows and do not compromise data integrity or interoperability.

Background

Medicinal products are a fundamental component of healthcare information systems. Accurate and interoperable representation of medications supports a wide range of healthcare activities, including prescribing, dispensing, medication administration, pharmacovigilance, reimbursement, supply chain management, analytics, and research.

SNOMED CT provides a structured terminology model for representing medicinal products within the Pharmaceutical and Biologic Product hierarchy. This model represents medicines at multiple levels of abstraction, including ingredient-based medicinal products, medicinal product forms, clinical drugs defined by ingredient, strength, and dose form, and real-world authorized products and packages.

The SNOMED CT International Release provides concepts describing medicinal products in a manner that is internationally consistent and independent of national regulatory environments. However, many aspects of drug representation; such as authorized product names, proprietary dose forms, packaging characteristics, and locally marketed products, are specific to individual jurisdictions. These are represented through National SNOMED CT Drug Extensions.

The development and harmonization of national drug extensions is supported by the Drug Extension User Group (DEUG). The DEUG is a collaborative community of National Release Centers, regulators, and domain experts that defines best practices for representing medicinal products in SNOMED CT and promotes alignment between national drug extensions and the international drug model.

Together, the International drug model and national drug extensions enable consistent representation of medicinal products across healthcare systems while supporting national regulatory requirements and clinical workflows.

Objective

The objective of this implementation guide is to support the effective and consistent use of the SNOMED CT Drug Model in real-world settings, including both the International medicinal product model and national drug extensions.

Specifically, this guide aims to:

• Enable implementers to understand how the SNOMED CT Drug Model supports clinical, administrative, and analytic use cases

• Provide practical guidance for selecting and using appropriate drug concept classes in different contexts

• Support the alignment of national drug representations with the SNOMED CT International model

• Facilitate the implementation of interoperable drug data using SNOMED CT across systems and jurisdictions

This guide covers the implementation and use of the SNOMED CT Drug Model, including:

• The structure of the SNOMED CT medicinal product hierarchy

• The different drug concept classes (e.g. Medicinal Product, Medicinal Product Form, Clinical Drug, Real Clinical Drug) and their roles in implementation

• The relationship between the International drug model and National Drug Extensions

• Typical use cases for drug concepts in clinical, administrative, and analytic workflows

This guide does not cover:

• Detailed clinical modeling of medication-related concepts

• Terminology authoring processes or maintenance of SNOMED CT content, which are addressed in the SNOMED CT Editorial Guide and related authoring documentation

This guide is intended for stakeholders involved in the development, management, and implementation of SNOMED CT drug extensions.

National Release Centers are responsible for managing SNOMED CT content within their jurisdictions, including the development and maintenance of national extensions.

For NRCs, this guide provides guidance on:

• The benefits of using SNOMED CT to represent medicinal products

• The principles of the SNOMED CT drug model

• The steps involved in creating and maintaining National SNOMED CT Drug Extensions

• Harmonizing existing national drug dictionaries with the SNOMED CT drug model

Implementers include organizations deploying SNOMED CT drug extensions within healthcare systems such as:

• Electronic Health Records (EHRs)

• Pharmacy systems

• ePrescribing platforms

• Clinical decision support systems

For implementers, this guide provides guidance on:

• Deploying and using SNOMED CT drug extensions in clinical systems

• Implementation best practice principles

• Understanding the role of the different drug model classes and their relationship to specific use cases

• Selecting appropriate drug concept levels for different workflows

This implementation guide is organized into the following sections:

Provides background information on the SNOMED CT Drug Model, the objectives and scope of the guide, and the intended audience. It also introduces the role of the Drug Extension User Group (DEUG) and the relationship between the International drug model and national drug extensions.

Describes the main clinical, administrative, and analytic use cases supported by the SNOMED CT drug model. These use cases illustrate how the different drug model concept classes (e.g. Medicinal Product, Medicinal Product Form, Clinical Drug, Real Clinical Drug) are used across healthcare workflows such as prescribing, dispensing, administration, pharmacovigilance, procurement, and reporting.

Provides an overview of how medicinal products are represented in SNOMED CT. This section explains the structure of the Pharmaceutical / Biologic Product hierarchy, the different concept classes in the drug model, and the relationship between the International medicinal product model and national drug extensions.

Describes how SNOMED CT drug concepts are used within healthcare information models. This section explains how drug concepts are bound to data elements in clinical systems and how they support interoperability across workflows such as prescribing, dispensing, medication administration, and reporting.

Provides implementation guidance for using SNOMED CT drug concepts in healthcare systems. This includes best practices for storing and querying SNOMED CT drug data, integrating national drug extensions, mapping national drug dictionaries, and supporting analytics and reporting

Querying SNOMED CT drug content is a fundamental capability for supporting clinical workflows, product selection, and analytics.

Because drug concepts are defined using structured attributes, effective querying depends on understanding both the hierarchy and the concept model.

The SNOMED CT Drug Model is designed to enable flexible querying across:

• hierarchical relationships (e.g. ingredient → product → package)

• defining attributes (e.g. ingredient, dose form, strength)

SNOMED CT drug content is distributed using Release Format 2 (RF2), the standard format for both the International Edition and all SNOMED CT extensions.

More information

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.

The international model provides the clinical definition of medicinal products, focusing on characteristics such as:

Introduction

National drug extensions enable the representation of real-world medicinal products within the SNOMED CT drug model, complementing the international semantic backbone with country-specific content such as authorized products and packaged medicines.

The development of a drug extension requires adherence to a set of principles that ensure:

• alignment with the SNOMED CT concept model

• consistency across international and national content

• scalability through semi-automated processes

• interoperability with local drug dictionaries and regulatory sources

This chapter outlines the key principles for both overall extension strategy and authoring processes.

Drug extensions are built on top of the SNOMED CT International Edition and must align with its concept model and hierarchy. The international model provides the core semantic structure through concepts such as:

• substances

• medicinal products (MP)

• medicinal product forms (MPF)

• clinical drugs (CD)

In some cases, national extensions may need to create concepts that logically belong to the international model, such as:

• new substances

• MPs, MPFs, or CDs not yet present

These concepts may subsequently be promoted to the International Edition following review by SNOMED International.

The creation of international-level concepts by National Release Centers (NRCs) introduces coordination challenges, particularly where multiple countries may require the same concepts.

To reduce duplication and competition:

• SNOMED International is taking a more proactive role in creating substance concepts, for example by aligning with regulatory sources such as the European Medicines Agency (EMA)

• The creation of Medicinal Products (MPs) is also planned centrally

• Requests for MPFs and CDs can be submitted by NRCs and incorporated into the International Edition

This approach supports consistency, reduces duplication of effort, and ensures a shared foundation across extensions.

A clear distinction should be maintained between:

• International content: abstract, reusable concepts supporting interoperability

• National extension content: real-world products, packages, and regulatory-specific information

National extensions should:

• reuse international concepts wherever possible

• only create new concepts when necessary

• ensure that extension concepts are logically aligned with the international model

Overview

The SNOMED CT International Drug Model provides a standardized framework for representing medicinal products in a manner that is consistent across countries and healthcare systems. The model is part of the Pharmaceutical / Biologic Product hierarchy and defines a set of concept classes that represent medicinal products at different levels of abstraction.

The international model focuses on representing the clinical characteristics of medicinal products, including:

• active ingredient(s)

• dose form

• strength

These characteristics allow medicines to be represented in a way that is independent of local brand names, packaging, or regulatory authorizations.

The international drug model defines several concept classes that represent medicinal products at different levels of abstraction. These concept classes allow systems to represent medications with the level of detail required for different clinical and administrative workflows.

A Medicinal Product represents a medicinal product defined only by its active ingredient(s). It does not specify dose form or strength.

This level is commonly used for:

• ingredient-based decision support rules

• drug interaction checking

• pharmacovigilance analysis

• high-level reporting and analytics

A Medicinal Product Form represents a medicinal product defined by active ingredient(s) and dose form, but without specifying strength.

This level allows grouping of products that share the same ingredient and pharmaceutical form.

Typical uses include:

• prescribing templates

• clinical decision support rules specific to dose form

• reporting and aggregation

A Clinical Drug represents a medicinal product defined by:

• active ingredient(s)

• strength

• manufactured dose form

This level provides the detail required for most clinical workflows such as prescribing and medication administration.

Clinical Drug concepts represent generic clinical specifications of medicines, independent of brand names or manufacturers.

The concept classes of the international drug model form a hierarchy that supports aggregation and semantic reasoning.

For example:

This hierarchical structure allows:

• aggregation of detailed data for reporting

• decision support rules defined at the ingredient level to apply to all related products

• consistent interpretation of medication data across systems

The international drug model uses a set of defining attributes to describe medicinal products. These attributes allow drug concepts to be formally defined and classified within the SNOMED CT hierarchy.

Common attributes include:

These attributes enable consistent modeling and automated classification of medicinal product concepts.

The international drug model provides the clinical foundation for representing medicinal products, but it does not represent jurisdiction-specific details such as:

• brand names

• authorized products

• packaging information

• pack sizes

These concepts are represented in National SNOMED CT Drug Extensions, which extend the international model to support local regulatory and clinical requirements.

For example:

The international model therefore provides the semantic backbone for national drug extensions, ensuring that medicines can be represented consistently across jurisdictions.

Overview

Most countries maintain a national drug dictionary or medicinal product registry, which serves as the authoritative source for:

• authorized medicinal products

• brand names and manufacturers

• packaging and presentation

• regulatory and reimbursement information

These national dictionaries are typically used operationally in:

• prescribing systems

• pharmacy and dispensing systems

• reimbursement and regulatory workflows

To enable interoperability and alignment with SNOMED CT, it is necessary to establish systematic mappings between the national drug dictionary and SNOMED CT drug concepts.

In addition, the SNOMED CT drug model is aligned with the ISO IDMP family of standards. As a result, national drug dictionaries that are structured according to IDMP, or that adopt compatible standards, can be mapped more efficiently and consistently to SNOMED CT. This is particularly relevant for key elements such as substances, strengths, and dose forms. For example, the use of dose forms aligned with European Directorate for the Quality of Medicines & HealthCare standard terms facilitates direct or near-direct mapping to SNOMED CT concepts, reducing ambiguity and improving interoperability across systems.

In most jurisdictions, national drug dictionaries are:

• maintained by regulatory or national bodies

• updated regularly based on product authorizations and withdrawals

• structured according to national pharmaceutical standards

The integration with SNOMED CT is therefore not a one-time activity, but part of an ongoing synchronization process between:

• the national drug dictionary

• the SNOMED CT International Edition

• the SNOMED CT national extension (if implemented)

This process is typically managed by the National Release Center (NRC) or an equivalent authority.

Mapping from a national drug dictionary to SNOMED CT is typically performed as a semi-automated, systematic process, rather than manual concept-by-concept mapping.

The process generally includes:

• mapping atomic elements

  such as substances, dose forms, and units of measure

• deriving structured drug concepts

  based on combinations of these elements (e.g. ingredient + strength + dose form)

• linking national product entries to SNOMED CT concepts

  at the appropriate level:

This approach ensures consistency and scalability across large national datasets.

Mappings between national drug dictionaries and SNOMED CT may be represented in different ways depending on national infrastructure.

In many countries, mappings are maintained within national systems or databases, for example:

• as part of the national drug dictionary

• within regulatory or reimbursement systems

• in dedicated mapping tables

This approach allows tight integration with national workflows but may be less portable across systems.

Alternatively, mappings may be represented using SNOMED CT reference sets (refsets).

This approach enables:

• alignment with SNOMED CT distribution formats (RF2)

• versioning and traceability of mappings

• reuse across multiple systems within a country

• easier sharing between jurisdictions

For national implementations that publish SNOMED CT extensions, representing mappings as refsets is often the preferred approach.

National drug dictionaries often contain detailed product information, including:

• brand names

• manufacturers

• packaging

Mappings should therefore be established at the appropriate level of the SNOMED CT Drug Model, typically:

• CD (Clinical Drug) for clinical equivalence

• RCD (Real Clinical Drug) for specific authorized products

• RPCD (Real Clinical Drug Package) for packaged products

In some cases, mappings may also be required at more abstract levels (e.g. MP) for aggregation or reporting.

Mapping between national drug dictionaries and SNOMED CT must be maintained as part of routine national processes.

This includes:

• updating mappings when new products are introduced

• removing or updating mappings when products are withdrawn

• aligning mappings with updates to SNOMED CT releases

• ensuring consistency between national data and SNOMED CT content

Because both national drug dictionaries and SNOMED CT evolve over time, synchronization is an ongoing process rather than a one-time activity.

SNOMED CT drug content, whether part of the International Edition or a national drug extension, is distributed using Release Format 2 (RF2). RF2 provides a structured, tabular representation of terminology components, enabling consistent storage, exchange, and processing of SNOMED CT data.

In RF2, a medicinal product is not represented as a single record, but as a set of coordinated entries across multiple files:

• the Concept file identifies the drug concept

• the Description file provides human-readable names

Introduction

HL7® FHIR® (Fast Healthcare Interoperability Resources) is widely used to exchange medication information between healthcare systems. The SNOMED CT Drug Model can be used as a terminology for representing medications within FHIR resources, enabling interoperable and semantically consistent medication workflows.

This section provides examples of how SNOMED CT drug concepts are bound to key FHIR resources across common use cases, including prescribing, dispensing, administration, and medication history.

The examples illustrate:

• how different SNOMED CT drug model concept levels (MP, MPF, CD, RCD, RPCD) are used

• how these concepts are represented in FHIR resources

• how terminology bindings support interoperability and traceability across workflows

When using the SNOMED CT Drug Model in FHIR resources, terminology bindings should be carefully aligned with the role of each resource within the medication workflow.

The following principles should be applied:

• Use Clinical Drug (CD) for prescribing to ensure a precise and interoperable definition of the intended medication, including ingredient, strength, and dose form

• Use Real Clinical Drug (RCD) for dispensing and administration to capture the exact product supplied or administered

• Use SNOMED CT consistently across all medication-related resources to support traceability across prescribing, dispensing, and administration workflows

In FHIR, SNOMED CT drug concepts are typically bound to CodeableConcept elements, such as medicationCodeableConcept. The selection of the appropriate SNOMED CT concept level for these elements is critical, as it determines the level of clinical detail and supports safe, consistent interpretation of medication data across systems.

Although the same data element may be used across multiple FHIR resources, its meaning depends on the context in which it is used:

• In MedicationRequest, .medicationCodeableConcept represents the prescribed medication and is therefore typically bound to a Clinical Drug (CD)

• In MedicationDispense and MedicationAdministration, the same element represents the actual product supplied or administered and is therefore bound to a Real Clinical Drug (RCD)

• In MedicationStatement, the element may be bound to either a CD or an RCD, depending on the level of detail available

Clearly identifying both the specific FHIR data element and its role within the workflow is essential to ensure that terminology bindings are applied consistently, safely, and interoperably across implementations.

The FHIR Medication resource represents a medication definition that can be referenced by other resources. It provides a reusable representation of a medicinal product across systems.

In prescribing workflows, the Medication resource is typically populated using a Clinical Drug (CD) concept. This represents the intended medication independently of any specific brand or manufacturer, supporting consistency in prescribing and enabling substitution during dispensing.

• Concept level: Clinical Drug (CD)

• Use case: Generic prescribing, reusable medication definition

The MedicationRequest resource represents a prescription issued by a clinician and captures the clinical intent, including the medication and dosage instructions.

For prescribing, the medication is represented using a Clinical Drug (CD) to ensure that the prescription clearly specifies the active ingredient, strength, and dose form, while remaining independent of any specific brand. This allows pharmacists to safely substitute equivalent products during dispensing.

• Concept level: Clinical Drug (CD)

• Rationale: Provides a precise and interoperable definition of the prescribed medication

The MedicationDispense resource records the medication actually supplied by the pharmacy.

At this stage, it is important to capture the exact product dispensed, including brand and manufacturer where applicable. Therefore, a Real Clinical Drug (RCD) concept is used. This ensures traceability between what was prescribed and what was dispensed, and supports pharmacovigilance and reimbursement processes.

• Concept level: Real Clinical Drug (RCD)

• Rationale: Captures the exact product supplied to the patient

The MedicationAdministration resource records the medication actually administered to the patient, typically in a clinical setting.

At this stage, it is critical to record the exact product administered, as this directly impacts patient safety, auditing, and clinical outcomes. Therefore, the medication is represented using a Real Clinical Drug (RCD).

In addition, the route of administration is captured using SNOMED CT qualifier values to ensure consistent and interoperable representation.

• Concept level: Real Clinical Drug (RCD)

• Additional binding: Route represented using SNOMED CT qualifier values

• Rationale: Ensures accurate recording of both the administered product and the route of administration

The MedicationStatement resource represents medications that a patient is taking or has taken, based on patient report, clinical records, or other sources.

The level of detail available in medication history may vary. In some cases, only the generic drug is known, while in others the exact product may be recorded. Therefore, both Clinical Drug (CD) and Real Clinical Drug (RCD) concepts may be used.

This flexibility allows medication history to be recorded accurately while still supporting clinical decision support and analytics.

• Concept level: Clinical Drug (CD) or Real Clinical Drug (RCD)

• Rationale: Supports varying levels of detail depending on available information

Different healthcare workflows require the use of different SNOMED CT drug model concept levels, depending on whether the focus is on clinical intent, real-world products, packaging, or aggregation.

This section summarizes how SNOMED CT concepts are typically bound to data elements across common use cases, ensuring consistent and safe interpretation of medication data.

Prescribing

Prescribing is typically based on Clinical Drugs (CD) to represent the intended medication. In some cases, prescribing may specify a brand (RCD) or a package (CDP/RPCD), depending on clinical or regulatory requirements.

Dispensing translates the prescribed drug into a specific product (RCD) or packaged product (RPCD), reflecting what is actually supplied.

Administration records the actual product (RCD) given to the patient. The Clinical Drug (CD) may be used for equivalence checks or clinical reasoning. The route is captured separately, typically using SNOMED CT qualifier values.

Inventory systems operate primarily at the package level (RPCD/CDP), while CD supports aggregation and reporting across products.

Procurement processes typically specify requirements using CDs, allowing suppliers to respond with RCDs and associated packaged products (RPCDs).

Reimbursement rules may apply at different levels of abstraction, from ingredient (MP) to form (MPF) to specific strength (CD).

Clinical decision support operates across multiple levels, depending on the rule:

• MP for interactions

• MPF for form-specific logic

• CD for dose validation

Adverse event reporting may require different levels of detail, from specific product (RCD) to generic drug (CD) or ingredient (MP), depending on data availability and reporting requirements.

Analytics typically uses MP and MPF for aggregation, with CD enabling more detailed analysis when needed.

Terminology bindings for drug content must align with both the data element and the clinical or operational workflow in which it is used. The selected SNOMED CT concept level should provide sufficient detail to support safe and accurate use of medications, while also enabling interoperability, aggregation, and traceability across systems.

A key aspect of terminology binding is that drug concepts are not used in isolation; they are always bound to structured data elements within an information model. The meaning of the data element determines the appropriate level of abstraction in the SNOMED CT drug model.

Terminology binding ensures that:

• the appropriate drug model concept level is used for each data element

• medication data is represented consistently across systems

Introduction

The SNOMED CT Pharmaceutical / Biologic Product hierarchy provides a structured model for representing medicinal products at multiple levels of abstraction. This hierarchy includes concepts such as Medicinal Product (MP), Medicinal Product Form (MPF), and Clinical Drug (CD), which progressively add detail about ingredients, dose form, and strength.

For example:

• A Medicinal Product (MP) represents a medicinal product defined only by its active ingredient(s), without specifying strength or dose form.

• A Clinical Drug (CD) represents a medicinal product defined by ingredient, strength, and manufactured dose form, making it suitable for use in clinical workflows.

The International Release focuses on representing medicinal products in a way that is globally consistent, while national extensions may add concepts representing actual authorized products and packaging available in specific jurisdictions, including branded medicines and product packages.

Together, the International Drug Model and National Drug Extensions support a wide range of healthcare use cases including prescribing, dispensing, logistics, reimbursement, pharmacovigilance, and clinical decision support.

Administrative use cases support operational and financial aspects of healthcare systems such as procurement, logistics, and reporting.

Healthcare organizations and national procurement agencies often purchase medicines through competitive tendering processes. In these processes, the purchasing authority defines the medication required using a generic specification, allowing suppliers to compete with their own authorized products.

The SNOMED CT drug model supports this process by separating generic drug definitions from real products available on the market. Procurement specifications can reference Clinical Drug (CD) concepts, while suppliers offer their products using Real Clinical Drug (RCD) and Real packaged Clinical Drug (RPCD) concepts defined in national extensions.

This approach ensures vendor-neutral procurement while maintaining precise definitions of the medicines being purchased.

Hospital pharmacies and distribution systems manage inventories of medications across warehouses, pharmacies, and clinical units. Stock management systems track package quantities, expiration dates, and product movement.

The SNOMED CT drug model supports these workflows by representing product packages using concepts such as Clinical Drug Package (CDP) and Real Clinical Drug Package (RPCD).

This allows inventory systems to track real packages while maintaining a link to the underlying clinical drug concept, and make this information available during the prescription process when necessary.

Health insurance systems and national payers define reimbursement policies for medications based on ingredients, formulations, or specific products.

The SNOMED CT drug model enables reimbursement rules to be defined at different levels of abstraction. For example, coverage policies may apply to all products containing a given ingredient or may apply only to specific strengths or formulations.

Healthcare organizations and public health authorities routinely analyze medication usage data to monitor prescribing patterns, drug costs, and treatment trends, and to support business intelligence activities such as forecasting demand, planning procurement, and optimizing medication supply.

The hierarchical structure of the SNOMED CT drug model enables aggregation of medication data at different levels of granularity. Data recorded at the clinical drug level can be automatically aggregated at higher levels, such as ingredient or drug class.

Clinical use cases focus on the use of medications in patient care workflows.

Electronic prescribing systems allow clinicians to select medications and send prescriptions electronically to pharmacies. These systems must represent medications with sufficient detail to ensure accurate dispensing.

SNOMED CT Clinical Drug (CD) concepts provide the appropriate level of detail for prescribing because they specify ingredient, strength, and dose form. In some cases, clinicians may prescribe a specific brand or package using Real Clinical Drug (RCD) or Real Packaged Clinical Drug (RPCD) concepts.

When a pharmacy receives a prescription, the pharmacist selects a product that fulfills the prescription. In many healthcare systems, pharmacists are allowed to substitute equivalent generic medicines.

The SNOMED CT drug model supports this workflow by linking Clinical Drug concepts with Real Clinical Drug concepts, enabling pharmacy systems to match prescriptions with available products.

In hospitals and other care settings, nurses administer medications to patients according to physician orders. Medication administration systems must record the exact product administered and verify that it matches the prescribed medication. Clinical decision support systems can support the administration step by checking contraindications, potential drug interactions, and dose appropriateness before the medication is given.

Closed-loop medication administration systems often use barcode scanning to identify the medication product before administration.

Pharmacovigilance systems collect reports of adverse reactions associated with medications. These systems must accurately identify the suspected drug to detect safety signals. If adverse reaction reports are generated directly from medication administration data recorded in the clinical record, the exact product administered can be captured without information loss, ensuring that the same product is reported to pharmacovigilance systems.

The SNOMED CT drug model allows adverse reactions to be recorded at different levels of specificity depending on available information.

Clinical decision support systems analyze medication orders and patient information to provide alerts and guidance to clinicians.

Typical decision support functions include drug–drug interaction checking, allergy alerts, and dose range validation.

The SNOMED CT drug model also supports knowledge management, research, and secondary uses of medication data.

Healthcare organizations and knowledge provider companies maintain drug knowledge databases containing information about drug interactions, contraindications, dosing guidance, and therapeutic indications.

The SNOMED CT drug model allows knowledge to be linked to standardized drug concepts, enabling consistent application and simple integration across clinical systems.

Electronic health records maintain medication lists representing drugs that a patient is currently taking or has taken previously. These lists support medication reconciliation and continuity of care.

Medication records may represent drugs at different levels depending on available information.

Researchers and public health authorities analyze medication data to study treatment outcomes, safety, and prescribing trends. Current medication use is also commonly used as a criterion for patient selection and eligibility in clinical studies.

The hierarchical structure of SNOMED CT drug concepts allows researchers to aggregate medication data at different levels.

Overview

The SNOMED CT Drug Extension Model provides a standardized framework for representing real-world medicinal products that are authorized and available within a specific jurisdiction.

While the SNOMED CT International Drug Model represents medicinal products in a jurisdiction-independent and abstract manner, national healthcare systems require additional information to support operational and regulatory use cases. These include:

• brand or proprietary names

• manufacturer or marketing authorization holder

• packaging and presentation

• locally authorized and marketed products

Drug extensions address these requirements by extending the international medicinal product hierarchy with additional concept classes that represent specific products and packages, while maintaining semantic alignment with the International Edition.

The extension model ensures that real-world medicinal products can be represented in a way that supports clinical use, supply chain processes, and regulatory requirements, without compromising interoperability.

The drug extension model defines additional concept classes that represent authorized products and their packaging. These concept classes complement the international model and provide the level of detail required for operational workflows.

A Real Clinical Drug (RCD) represents a medicinal product that is authorized and marketed within a specific jurisdiction.

An RCD is defined as a specialization of a Clinical Drug (CD) and therefore includes:

• active ingredient(s)

• strength

• manufactured dose form

In addition, it includes product-specific characteristics such as:

• brand or proprietary name

• manufacturer or supplier

• regulatory authorization

This level is commonly used for:

• pharmacy dispensing

• medication administration

• pharmacovigilance reporting

• reimbursement and billing

Example:

• Clinical Drug (CD):

  Product containing precisely amoxicillin 500 milligram oral capsule (clinical drug)

• Real Clinical Drug (RCD):

  BrandX amoxicillin 500 milligram oral capsule (real clinical drug)

A Clinical Drug Package (CDP) represents a generic packaged medicinal product, defined by packaging characteristics but not tied to a specific branded product.

A CDP is derived from a Clinical Drug and includes:

• pack size

• unit of presentation

• container type

This level is commonly used for:

• procurement specifications

• logistics planning

• supply chain management

Example:

• Clinical Drug (CD):

  Product containing precisely amoxicillin 500 milligram oral capsule (clinical drug)

• Clinical Drug Package (CDP):

  Product containing precisely amoxicillin 500 milligram oral capsule box of 24 (clinical drug package)

A Real Clinical Drug Package (RPCD) represents a specific packaged medicinal product available in the supply chain.

An RPCD combines:

• a Real Clinical Drug (RCD)

• packaging characteristics

This level is commonly used for:

• pharmacy inventory systems

• medication dispensing systems

• supply chain management

• regulatory tracking and traceability

Example:

• Real Clinical Drug (RCD):

  Brand X amoxicillin 500 milligram oral capsule (real clinical drug)

• Real Clinical Drug Package (RPCD):

  Brand X amoxicillin 500 milligram oral capsule box of 24 (real clinical drug package)

The drug extension model extends the international hierarchy by adding concept classes that represent real-world products and packaging.

The combined model can be illustrated as follows:

This structure reflects two complementary pathways:

• a real product pathway (CD → RCD → RPCD)

• a generic packaging pathway (CD → CDP)

The Clinical Drug Package (CDP) concept class is not shown in this hierarchical representation because it does not form part of the main vertical specialization pathway from abstract to concrete medicinal products.

The diagram illustrates a single lineage of increasing specificity, where each concept is a direct specialization of the previous one:

• MP → MPF → CD → RCD → RPCD

In this pathway, each step adds additional defining attributes to represent the same medicinal product with increasing specificity, culminating in a specific packaged product (RPCD).

In contrast, CDP represents a parallel packaging abstraction:

• A CDP is derived from a Clinical Drug (CD)

• It introduces packaging attributes (e.g. pack size, container type)

• However, it does not represent a specific real-world product, as it lacks product identity (e.g. brand, manufacturer)

Therefore:

• CDP is not a parent of RCD or RPCD

• CDP does not sit on the direct specialization path from CD to RPCD

• CDP exists as a parallel branch used for generic packaging representations

Conceptually, the structure can be understood as:

This distinction is important because:

• The RCD → RPCD pathway supports clinical and operational workflows involving real products

• The CDP pathway supports administrative and logistical use cases such as procurement and planning

This layered structure ensures that:

• clinical meaning is defined internationally, while product-specific details are added nationally

• clinical rules and decision support defined at the international level apply to extension concepts

• aggregation across concept levels remains consistent (e.g. RCD → CD → MP)

• interoperability is preserved across jurisdictions

Drug extension concepts use additional attributes to represent characteristics specific to real-world medicinal products. These attributes are applied in a structured way according to the concept class.

Some attributes are used across multiple extension concept classes (particularly RCD and RPCD) to represent product identity and regulatory context.

These include:

• Has product name (attribute)

• Has manufacturer (attribute)

• Has marketing authorization (attribute)

• Has intended site / jurisdiction (attribute)

These attributes ensure that extension concepts represent real-world authorized products, while remaining linked to their clinical definitions.

All extension concepts ultimately derive from international drug concepts and therefore inherit core defining attributes such as:

• Has active ingredient (attribute)

• Has manufactured dose form (attribute)

• Has presentation strength (attribute)

• Has concentration strength (attribute) (where applicable)

These attributes define the clinical meaning of the medicinal product and remain consistent across international and national content.

RCD concepts extend Clinical Drugs by adding attributes that identify a specific authorized product:

• Has product name (attribute)

• Has manufacturer (attribute)

• Has marketing authorization (attribute)

These attributes distinguish products that share the same clinical definition but differ in branding or regulatory status.

CDP concepts add packaging information to a Clinical Drug:

• Has pack size (attribute)

• Has unit of presentation (attribute)

• Has container type (attribute)

These attributes describe packaging independently of any specific product.

RPCD concepts combine both product identity and packaging:

• product-level attributes (inherited from RCD)

• packaging attributes (as in CDP), including:

  • Has pack size (attribute)

  • Has unit of presentation (attribute)

This allows full representation of the exact packaged product