Overview
EN ISO 10993-23:2021/A1:2025 is an amendment to ISO 10993-23:2021 - the part of the ISO 10993 series that specifies tests for irritation as part of the biological evaluation of medical devices. Amendment A1 (2025) adds additional in vitro reconstructed human epidermis (RhE) models for skin irritation assessment and clarifies the role of RhE tests adapted for medical device extracts. This European adoption (EN ISO) was approved by CEN in January 2025 and is intended to support compliance with Regulation (EU) 2017/745 (EU MDR).
Key topics and requirements
- Addition of RhE models: The amendment expands acceptable reconstructed human epidermis models for in vitro skin irritation testing, acknowledging multiple validated RhE systems.
- In vitro focus: Emphasises replacement or reduction of animal tests by using validated in vitro methods for detecting skin irritancy of neat chemicals and device extracts.
- Adaptation for medical device extracts: Notes the method’s use for extracts of materials and residues from medical devices, not only pure chemicals.
- Regulatory alignment: Annex ZA links normative clauses to the General Safety and Performance Requirements of Regulation (EU) 2017/745 and explains conditions for presumption of conformity.
- Normative references: The amendment works alongside other ISO 10993 parts (for example ISO 10993-1, -12, -18) and international test methods such as OECD 439 (in vitro skin irritation - RhE test method) and OECD 404 (in vivo dermal irritation/corrosion) where relevant.
- Implementation notes: CEN foreword requires national adoption by CEN members and highlights potential patent issues and the need to consult the Official Journal for harmonisation status.
Practical applications and who uses it
- Medical device manufacturers: to design biological evaluation strategies and determine when RhE-based in vitro irritation testing is appropriate for device materials, residues or extracts.
- Contract testing laboratories: to implement validated RhE test models and report irritation data consistent with ISO 10993 requirements.
- Regulatory affairs and compliance teams: to support technical documentation and achieve presumption of conformity with EU MDR when normative clauses are applied.
- Notified bodies and toxicologists: to review irritation testing strategies, interpret RhE data and integrate results into risk management and clinical evaluation.
Related standards
- ISO 10993 series (notably ISO 10993-1, -12, -18)
- OECD 439 - In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method
- OECD 404 - Acute Dermal Irritation/Corrosion (referenced where animal data remain applicable)
This amendment advances non-animal testing for skin irritation, clarifies use of multiple RhE models for medical device extracts, and helps stakeholders align irritation testing with current regulatory expectations (ISO 10993-23, RhE models, in vitro skin irritation, EU MDR).
