Case Study: ePrescribing in EU and Ireland – A Solution Architect’s Guide to FHIR-Based Electronic Prescription Systems

Electronic prescribing (ePrescribing) is transforming medication management across Europe and Ireland, replacing error-prone paper prescriptions with secure digital workflows. This comprehensive case study examines the regulatory landscape, FHIR-based implementation patterns, enterprise architecture decisions, and practical guidance for building compliant ePrescribing systems in the European context.

Executive Summary

This case study presents a comprehensive Solution Architect’s perspective on implementing FHIR-based electronic prescribing systems within the European Union and Ireland specifically. Drawing from the “Digital for Care: A Digital Health Framework for Ireland 2024-2030” published by the Department of Health in May 2024, and aligning with the EU’s eHealth Digital Service Infrastructure (eHDSI) requirements, we examine the end-to-end architectural considerations for building production-grade ePrescribing platforms.

ePrescribing delivers significant, measurable benefits:

• Reduced medication errors: Studies indicate up to 70% reduction in prescription errors through elimination of illegible handwriting, automated drug-drug interaction checks, and dosage validation
• Improved patient safety: Real-time allergy checking, therapeutic duplication alerts, and contraindication warnings at point of prescribing
• Better adherence tracking: Complete visibility into prescription fulfillment rates, enabling proactive patient outreach
• Streamlined pharmacy workflows: Elimination of manual prescription transcription, reducing dispensing time by 40-60%
• Cross-border care continuity: EU citizens can obtain medications while traveling through MyHealth@EU infrastructure

In the EU, the Cross-Border Health Directive and eHealth Digital Service Infrastructure (eHDSI) provide the framework for cross-border prescription recognition. Ireland’s Health Service Executive (HSE), through eHealth Ireland, is actively implementing national ePrescribing aligned with these EU standards while addressing Ireland-specific regulatory requirements.

Case Study Context: Ireland’s National ePrescribing Journey

Ireland’s path to national electronic prescribing represents a multi-year transformation journey that accelerated significantly following the COVID-19 pandemic. Understanding this context is essential for architects designing systems that must integrate with Ireland’s evolving healthcare infrastructure.

Historical Background

Prior to 2020, Ireland’s prescription workflows were predominantly paper-based. GPs would handwrite or print prescriptions, patients would physically transport these documents to pharmacies, and pharmacists would manually enter prescription details into dispensing systems. This workflow introduced multiple failure points:

• Illegibility: Handwritten prescriptions were frequently misread, leading to dispensing of incorrect medications or dosages
• Loss and fraud: Paper prescriptions could be lost, stolen, or forged
• No real-time verification: Pharmacists had no mechanism to verify prescriber credentials or check for duplicate prescriptions
• Limited clinical decision support: Drug interaction checking was impossible without access to the patient’s complete medication history
• Audit gaps: Paper trails were incomplete and difficult to audit for controlled substances

Emergency Digital Transformation (2020)

The COVID-19 pandemic in March 2020 created an urgent need for contactless prescription transfer. Emergency legislative changes enabled the electronic transfer of prescriptions via the HSE’s secure clinical email service, Healthmail. This interim solution, while not a full ePrescribing implementation, demonstrated the feasibility and benefits of digital prescription workflows.

Additionally, the High Tech Hub was integrated into the national electronic prescription transfer system in August 2020, specifically handling high-cost medications used in oncology, rheumatology, and other specialist areas. This provided valuable operational experience with electronic prescribing in a controlled context.

Digital for Care Framework (2024-2030)

The “Digital for Care: A Digital Health Framework for Ireland 2024-2030,” published on May 21, 2024, establishes the strategic foundation for Ireland’s digital health transformation. This framework explicitly prioritizes the National ePrescribing Project as a key deliverable, aiming to:

• Establish a single source of truth for prescribing and dispensing information for every patient
• Improve medication safety through electronic verification and clinical decision support
• Reduce administrative burden on healthcare providers
• Enable seamless data exchange with the developing National Shared Care Record (NSCR)
• Prepare for integration with EU cross-border health services (MyHealth@EU)

EU ePrescription Regulatory Framework

The European Union has established a comprehensive regulatory and technical framework for cross-border ePrescription services. Solution architects must understand this layered architecture to build systems that achieve both national compliance and EU interoperability.

Cross-Border Health Directive (2011/24/EU)

The Directive on the application of patients’ rights in cross-border healthcare establishes the legal foundation for healthcare service portability across EU member states. Key provisions relevant to ePrescribing include:

• Recognition of prescriptions issued in other member states
• Requirements for mutual recognition of prescribers
• Framework for reimbursement of cross-border healthcare costs
• Establishment of the eHealth Network for coordination

eHealth Digital Service Infrastructure (eHDSI)

The eHDSI, operating under the “MyHealth@EU” brand since 2018, provides the technical infrastructure for cross-border health data exchange. The architecture consists of:

graph TB
    subgraph CountryA ["Country A (Prescribing Country)"]
        GP["Prescriber"]
        EHR_A["National EHR/ePrescription System"]
        NCP_A["NCPeH-A
(National Contact Point)"]
    end
    
    subgraph EU ["EU Infrastructure"]
        OpenNCP["OpenNCP Platform"]
        CTS["Central Terminology Services"]
        MVC["Master Value Sets Catalogue"]
        MTC["Master Translation Catalogue"]
    end
    
    subgraph CountryB ["Country B (Dispensing Country)"]
        NCP_B["NCPeH-B
(National Contact Point)"]
        Pharmacy["Pharmacy System"]
        Patient["EU Citizen/Patient"]
    end
    
    GP --> EHR_A
    EHR_A --> NCP_A
    NCP_A --> OpenNCP
    OpenNCP --> CTS
    OpenNCP --> MVC
    OpenNCP --> MTC
    OpenNCP --> NCP_B
    NCP_B --> Pharmacy
    Patient --> Pharmacy
    
    style EU fill:#E8F5E9,stroke:#2E7D32
    style CountryA fill:#E3F2FD,stroke:#1565C0
    style CountryB fill:#FFF3E0,stroke:#EF6C00

National Contact Points for eHealth (NCPeH)

Each EU member state must establish a National Contact Point for eHealth. The NCPeH operates as a gateway between national health systems and the EU infrastructure. It has two interfaces:

• National Interface: Connects to domestic EHR systems, prescription databases, and healthcare registries. This interface is the sole responsibility of the member state and varies significantly between countries.
• International Interface: Standardized interface for communication with other NCPeHs via the OpenNCP platform. This interface follows common specifications developed within the eHDSI project.

OpenNCP Platform

The OpenNCP (Open Source National Contact Point) provides the reference implementation for NCPeH gateway services. Key capabilities include:

• Secure transport layer using TLS 1.3 and eIDAS-compliant certificates
• Document exchange based on IHE profiles (XDS, XCA, XCPD)
• Terminology translation via Central Terminology Services
• Audit logging compliant with GDPR and EU security requirements

Interoperability Mechanisms

To overcome the incompatibility of diverse national eHealth systems (different languages, coding systems, data formats), eHDSI employs several key mechanisms:

European Health Data Space (EHDS)

The EHDS Regulation, advancing through EU legislative processes in 2024-2025, will significantly expand the scope of health data exchange. For ePrescription, key provisions include:

• Mandatory EHR interoperability: All EHR systems must support the European Electronic Health Record Exchange Format (EEHRxF)
• Patient Summaries and ePrescription: By 2029, all member states must support cross-border exchange of these core data types
• HL7 FHIR adoption: FHIR is recognized as a key standard for implementing EHDS requirements
• Secondary use framework: Provisions for using prescription data for research and public health purposes

Ireland-Specific Requirements

Ireland’s ePrescribing implementation is led by the HSE through eHealth Ireland, integrating with national health identifiers and regulatory frameworks. Solution architects must account for several Ireland-specific requirements:

National Health Identifiers

• Individual Health Identifier (IHI): A unique, lifelong identifier assigned to every individual accessing health services in Ireland. The IHI is mandatory for all ePrescription transactions and serves as the primary patient identifier in FHIR resources.
• Health Practitioner Index (HPI): A registry of all healthcare practitioners authorized to provide services in Ireland. Prescribers must be registered in the HPI, and this identifier is used for authentication, authorization, and audit purposes.
• Health Organisation Identifier (HOI): Identifies healthcare organizations such as hospitals, GP practices, and pharmacies.

PCRS Integration

The Primary Care Reimbursement Service (PCRS) manages drug scheme eligibility and reimbursement in Ireland. ePrescribing systems must integrate with PCRS to:

• Verify patient eligibility for various drug schemes (Medical Card, Drug Payment Scheme, Long Term Illness)
• Apply correct pricing and reimbursement rules
• Submit claims for reimbursement
• Access the High Tech Hub for specialist medications

Controlled Drugs Regulations

Ireland’s Misuse of Drugs Regulations impose additional requirements for controlled substances (Schedule 2-5). The S.I. No. 529/2023 amendment updated regulations for electronic prescribing of controlled drugs through the national electronic prescription transfer system:

Medical Council Registration

Prescribers must be registered with the Irish Medical Council and maintain good standing. The ePrescribing system must validate prescriber credentials against the Medical Council register at the time of prescribing.

SNOMED CT and Irish Medication Terminology

Ireland joined SNOMED International in November 2016. eHealth Ireland releases a SNOMED CT Irish Extension biannually, which includes an Irish National Drug Extension for medicinal products. Unlike the UK’s dm+d, Ireland is developing its own drug dictionary with concepts contributed by organizations including the Irish Pharmacy Union (IPU). As of the October 2024 release (9th Irish Edition), the medication terminology is under active development.

Enterprise Architecture for ePrescribing

Designing an enterprise-grade ePrescribing solution requires careful consideration of multiple architectural dimensions. This section presents a reference architecture aligned with TOGAF principles and tailored for Irish/EU requirements.

System Context (C4 Level 1)

C4Context
    title System Context for National ePrescribing Platform
    Person(prescriber, "Prescriber", "GP, Hospital Doctor, or authorized prescriber")
    Person(pharmacist, "Pharmacist", "Community or hospital pharmacist")
    Person(patient, "Patient", "Individual receiving medication")
    
    System(neps, "National ePrescribing
Platform (NePS)", "Central prescription management, clinical decision support, and audit")
    
    System_Ext(ehr, "EHR Systems", "GP and hospital electronic health records")
    System_Ext(pharmacy, "Pharmacy Systems", "Dispensing and inventory management")
    System_Ext(ihi, "IHI Service", "National patient identifier registry")
    System_Ext(hpi, "HPI Service", "Health practitioner registry")
    System_Ext(pcrs, "PCRS", "Drug scheme eligibility and reimbursement")
    System_Ext(hpra, "HPRA Systems", "Controlled drug reporting")
    System_Ext(ncpeh, "NCPeH Ireland", "EU cross-border gateway")
    
    Rel(prescriber, ehr, "Creates prescriptions via")
    Rel(pharmacist, pharmacy, "Dispenses via")
    Rel(patient, neps, "Receives notifications from")
    
    Rel(ehr, neps, "Submits prescriptions to", "FHIR R4")
    Rel(pharmacy, neps, "Queries/dispenses via", "FHIR R4")
    Rel(neps, ihi, "Validates patient identity")
    Rel(neps, hpi, "Validates prescriber credentials")
    Rel(neps, pcrs, "Checks eligibility, submits claims")
    Rel(neps, hpra, "Reports controlled drugs")
    Rel(neps, ncpeh, "Cross-border exchange", "eHDSI")
    
    UpdateLayoutConfig($c4ShapeInRow="3", $c4BoundaryInRow="1")

Container Architecture (C4 Level 2)

C4Container
    title Container Diagram for National ePrescribing Platform

    Person(prescriber, "Prescriber", "")
    Person(pharmacist, "Pharmacist", "")
    
    System_Boundary(neps, "National ePrescribing Platform") {
        Container(api, "FHIR API Gateway", "Azure APIM + FHIR Server", "RESTful FHIR R4 interface for all integrations")
        Container(cds, "Clinical Decision Support", ".NET 8 + Rules Engine", "Drug interactions, allergies, dosage checks")
        Container(workflow, "Prescription Workflow", ".NET 8 Microservice", "Status management, notifications, audit")
        Container(identity, "Identity Service", "OIDC/OAuth 2.0", "Prescriber/patient authentication")
        ContainerDb(fhirdb, "FHIR Database", "Azure Cosmos DB", "Prescription resources, medication history")
        ContainerDb(auditdb, "Audit Database", "Azure SQL", "Immutable audit log for compliance")
        Container(events, "Event Bus", "Azure Service Bus", "Async notifications and integrations")
    }
    
    System_Ext(ehr, "EHR Systems", "")
    System_Ext(pharmacy, "Pharmacy Systems", "")
    System_Ext(external, "External Services", "IHI, HPI, PCRS, HPRA")
    
    Rel(prescriber, ehr, "Uses")
    Rel(pharmacist, pharmacy, "Uses")
    Rel(ehr, api, "FHIR MedicationRequest", "HTTPS/TLS 1.3")
    Rel(pharmacy, api, "FHIR queries/MedicationDispense", "HTTPS/TLS 1.3")
    Rel(api, identity, "Authenticates via")
    Rel(api, cds, "Invokes for prescription validation")
    Rel(api, workflow, "Manages prescription lifecycle")
    Rel(workflow, fhirdb, "Persists resources")
    Rel(workflow, auditdb, "Logs all actions")
    Rel(workflow, events, "Publishes notifications")
    Rel(api, external, "Validates/reports", "Secure APIs")

Key Design Decisions

FHIR Resources for ePrescribing

FHIR R4 provides the foundation for ePrescribing systems with specific resources designed for medication workflows. The following table summarizes the core resources and their roles:

MedicationRequest Example

{
  "resourceType": "MedicationRequest",
  "id": "prescription-001",
  "status": "active",
  "intent": "order",
  "medicationCodeableConcept": {
    "coding": [
      {
        "system": "http://snomed.info/sct",
        "code": "318127009",
        "display": "Amlodipine 5mg tablets"
      }
    ]
  },
  "subject": {
    "reference": "Patient/ihi-1234567890",
    "display": "John Murphy"
  },
  "authoredOn": "2025-05-19T09:30:00Z",
  "requester": {
    "reference": "Practitioner/hpi-98765",
    "display": "Dr. Sarah O'Brien"
  },
  "dosageInstruction": [
    {
      "text": "Take one tablet daily in the morning",
      "timing": {
        "repeat": {
          "frequency": 1,
          "period": 1,
          "periodUnit": "d",
          "when": ["MORN"]
        }
      },
      "doseAndRate": [
        {
          "doseQuantity": {
            "value": 1,
            "unit": "tablet",
            "system": "http://unitsofmeasure.org",
            "code": "{tbl}"
          }
        }
      ]
    }
  ],
  "dispenseRequest": {
    "numberOfRepeatsAllowed": 5,
    "quantity": {
      "value": 28,
      "unit": "tablet"
    },
    "expectedSupplyDuration": {
      "value": 28,
      "unit": "days"
    }
  }
}

ePrescribing Workflow

The following sequence diagram illustrates the end-to-end workflow from prescription creation through dispensing and notification:

sequenceDiagram
    participant GP as Prescriber
    participant EHR as EHR System
    participant NPS as National Prescription Server
    participant Pharm as Pharmacy
    participant Patient
    
    GP->>EHR: Create prescription
    EHR->>EHR: Clinical decision support
    EHR->>NPS: Submit MedicationRequest
    NPS-->>EHR: Prescription ID + barcode
    EHR-->>GP: Confirmation
    EHR-->>Patient: Notification (SMS/App)
    Patient->>Pharm: Present ID/barcode
    Pharm->>NPS: Query prescription
    NPS-->>Pharm: MedicationRequest details
    Pharm->>Pharm: Dispense medication
    Pharm->>NPS: Submit MedicationDispense
    NPS-->>EHR: Dispensation notification

Clinical Decision Support Integration

A robust Clinical Decision Support (CDS) layer is essential for realizing the safety benefits of ePrescribing. The CDS engine should provide real-time checks at the point of prescribing:

Drug-Drug Interactions

The CDS system queries the patient’s current medication list and checks for known interactions. Interactions are classified by severity:

• Contraindicated: Block prescription, require override with clinical justification
• Severe: Display warning, require acknowledgment before proceeding
• Moderate: Display informational alert
• Minor: Log for audit, no interruption

Allergy and Adverse Reaction Checking

Cross-references the prescribed medication against the patient’s documented allergies using the AllergyIntolerance resource. Must handle both specific medication allergies and class-based allergies (e.g., penicillin class).

Dosage Validation

Validates prescribed dosage against recommended ranges based on:

• Patient age (pediatric/adult/geriatric dosing)
• Patient weight (weight-based dosing)
• Renal function (dose adjustment for renal impairment)
• Hepatic function (dose adjustment for liver disease)
• Maximum daily dose limits

Therapeutic Duplication

Detects when a new prescription duplicates an existing active medication in the same therapeutic class. For example, prescribing two different ACE inhibitors or two benzodiazepines should trigger a review alert.

public class ClinicalDecisionSupportService
{
    private readonly IInteractionDatabase _interactionDb;
    private readonly IPatientMedicationService _medicationService;
    private readonly IAllergyService _allergyService;
    
    public async Task<CdsResult> EvaluatePrescriptionAsync(
        MedicationRequest request, 
        string patientId)
    {
        var result = new CdsResult();
        
        // Get patient's current medications
        var currentMeds = await _medicationService
            .GetActiveMedicationsAsync(patientId);
        
        // Check drug-drug interactions
        var interactions = await _interactionDb
            .CheckInteractionsAsync(request.Medication, currentMeds);
        
        foreach (var interaction in interactions)
        {
            result.AddAlert(new CdsAlert
            {
                Type = AlertType.DrugInteraction,
                Severity = interaction.Severity,
                Message = interaction.Description,
                RequiresOverride = interaction.Severity == Severity.Contraindicated
            });
        }
        
        // Check allergies
        var allergies = await _allergyService
            .GetPatientAllergiesAsync(patientId);
        
        if (allergies.Any(a => a.MatchesMedication(request.Medication)))
        {
            result.AddAlert(new CdsAlert
            {
                Type = AlertType.AllergyContraindication,
                Severity = Severity.Contraindicated,
                Message = "Patient has documented allergy to this medication",
                RequiresOverride = true
            });
        }
        
        // Check therapeutic duplication
        var duplicates = currentMeds
            .Where(m => m.TherapeuticClass == request.Medication.TherapeuticClass)
            .ToList();
        
        if (duplicates.Any())
        {
            result.AddAlert(new CdsAlert
            {
                Type = AlertType.TherapeuticDuplication,
                Severity = Severity.Moderate,
                Message = $"Patient already on {duplicates.First().Name} in same class"
            });
        }
        
        return result;
    }
}

Security and Compliance Architecture

ePrescribing systems handle sensitive personal health information and must implement comprehensive security controls. This section outlines the security architecture for an Irish/EU-compliant implementation.

GDPR Compliance

As a system processing health data (special category data under GDPR Article 9), ePrescribing platforms must implement:

• Lawful basis: Processing typically relies on Article 9(2)(h) – provision of health care
• Consent management: Document patient consent for data processing and cross-border exchange
• Data minimization: Transmit only necessary data elements for each use case
• Purpose limitation: Prescription data used only for treatment, dispensing, and authorized secondary uses
• Right of access: Patients can request copies of their prescription history
• Data portability: Export prescription data in FHIR format
• Right to erasure: Limited by retention requirements for controlled drug records

Authentication and Authorization

Audit Requirements

The audit subsystem must capture and retain:

• All prescription create, update, and cancel operations
• All dispensing events including partial dispenses
• All queries and data access events
• CDS override decisions with clinical justification
• Controlled drug reporting submissions to HPRA
• Cross-border data exchanges via NCPeH

Audit logs must be immutable, timestamped with a trusted time source, and retained for a minimum of 8 years (aligned with controlled drug record retention requirements).

Implementation Best Practices

Based on lessons learned from ePrescribing implementations across Europe and aligned with Irish requirements, the following best practices should guide implementation:

• Use standard terminologies: SNOMED CT for medications and clinical concepts, ICD-10 for diagnoses, EDQM for dose forms and routes
• Implement CDS alerts judiciously: Alert fatigue is real. Tune thresholds based on clinical significance and track override rates
• Support partial dispensing: Pharmacies must be able to dispense partial quantities and record remaining balance
• Handle cancellations gracefully: Clear workflow for voiding prescriptions before and after dispensing
• Audit everything: Comprehensive logging is non-negotiable for regulatory compliance
• Provide offline fallback: Print capability when systems are unavailable, with queued synchronization
• Document patient consent: GDPR requires explicit consent documentation for cross-border data exchange
• Plan for terminology evolution: The Irish National Drug Extension is actively developing; design for code updates
• Test with realistic data volumes: National-scale systems must handle millions of prescriptions annually
• Engage clinical stakeholders: Workflow design must involve prescribers and pharmacists to ensure usability

Integration Patterns

ePrescribing systems must integrate with multiple external services. The following patterns support robust integration:

Synchronous API Integration

Used for real-time validation and queries where immediate response is required:

• IHI validation (patient lookup)
• HPI verification (prescriber credentials)
• Drug scheme eligibility check (PCRS)
• Prescription query from pharmacy

Asynchronous Event-Driven Integration

Used for notifications and downstream updates that don’t require immediate acknowledgment:

• Patient notification (SMS/push) on new prescription
• EHR notification on dispensing event
• HPRA controlled drug reporting (batched)
• NCPeH cross-border prescription exchange

Resilience Patterns

• Circuit breaker: Prevent cascade failures when external services are degraded
• Retry with exponential backoff: Handle transient failures gracefully
• Timeout policies: Ensure prescribing workflow isn’t blocked by slow external services
• Fallback strategies: Continue core prescribing when non-critical services are unavailable
• Bulkhead isolation: Isolate integration points to prevent cross-contamination of failures

Testing Strategy

Comprehensive testing is critical for ePrescribing systems given their safety implications:

Key Takeaways

• ✅ EU eHDSI enables cross-border prescriptions: Build for MyHealth@EU interoperability from day one using OpenNCP and eHDSI specifications
• ✅ FHIR MedicationRequest is the core resource: Master the resource structure, extensions, and workflow patterns
• ✅ Ireland requires IHI/HPI integration: National health identifiers are mandatory for all prescription transactions
• ✅ Clinical decision support saves lives: Integrate comprehensive drug-drug interaction, allergy, and dosage checking
• ✅ GDPR compliance is non-negotiable: Document consent, minimize data, and implement robust access controls
• ✅ Controlled substances need special handling: Separate workflows, enhanced authentication, and HPRA reporting for Schedule 2-5 drugs
• ✅ Plan for EHDS requirements: The European Health Data Space will mandate enhanced interoperability by 2029
• ✅ Engage clinical stakeholders early: Usability directly impacts adoption and patient safety outcomes

Conclusion

ePrescribing represents a fundamental transformation in medication management, improving patient safety while enabling seamless cross-border healthcare across the European Union. Ireland’s journey—from emergency Healthmail solutions in 2020 to the comprehensive National ePrescribing Project outlined in “Digital for Care 2024-2030″—demonstrates both the urgency and complexity of this transformation.

For solution architects, the key challenge is balancing multiple competing requirements: national regulatory compliance, EU interoperability mandates, clinical safety imperatives, and the practical realities of integrating with diverse legacy systems. Success requires a standards-based foundation (FHIR R4, SNOMED CT, eHDSI specifications), robust clinical decision support, comprehensive security architecture, and deep engagement with clinical stakeholders.

The investment in standards-based ePrescribing implementation pays dividends through reduced medication errors, streamlined workflows, enhanced auditability, and future-proof architecture ready for the European Health Data Space. As HSE Ireland advances its national implementation, the patterns and practices outlined in this case study provide a blueprint for achieving these goals.

References

• EU Cross-Border Health Services (eHDSI/MyHealth@EU)
• HL7 FHIR MedicationRequest Resource (R4)
• HSE Prescription Services
• IHE Pharmacy Technical Framework
• Health Products Regulatory Authority (Ireland)
• Digital for Care: A Digital Health Framework for Ireland 2024-2030
• eHealth Ireland: National ePrescribing Project
• SNOMED CT Irish Extension (eHealth Ireland)
• HIQA Report on SNOMED CT Adoption in Ireland
• Directive 2011/24/EU on Cross-Border Healthcare
• European Health Data Space (EHDS)
• S.I. No. 150/2023 – Misuse of Drugs (Amendment) Regulations