ISO 10993-23:2021

Overview - ISO 10993-23:2021 (Tests for irritation)

ISO 10993-23:2021 is part of the ISO 10993 series on the biological evaluation of medical devices. It specifies procedures to assess the potential of medical devices, constituent materials or extracts to cause irritation of skin or mucosal tissues. The standard defines a step-wise evaluation framework that includes pre-test considerations, validated in vitro methods (including reconstructed human epidermis models) and, when necessary, in vivo animal tests and human skin tests. It also covers result interpretation, test acceptance criteria and reporting requirements.

Key topics and technical requirements

• Step-wise approach: Guidance to select appropriate testing (in silico → in vitro → in vivo → human), consistent with ISO 10993‑1 risk-based evaluation.
• Pre-test considerations: Material type, chemical composition, existing data sources, and decision criteria for testing route (dermal, mucosal).
• In vitro irritation tests: Use of reconstructed human epidermis (RhE) models, test system description, sample preparation, exposure procedures, and viability assessment (e.g., MTT assay) for prediction of irritation potential.
• In vivo irritation tests: Protocols for skin exposure and intracutaneous (intradermal) administration in animals, observation schedules, evaluation and reporting.
• Human skin irritation test: When appropriate, controlled human patch testing and associated ethical/consent considerations are described (see Annex E).
• Data interpretation and documentation: Prediction models, acceptance criteria, method documentation sheets and required test report elements.
• Supporting material: Annexes covering preparation of materials, checklists, special irritation test methods and background information.

Practical applications - who uses ISO 10993-23

• Medical device manufacturers: To evaluate irritation risk during product development, material selection and design validation.
• Regulatory and compliance teams: To assemble biocompatibility data for regulatory submissions and to meet regional requirements.
• Biocompatibility and safety engineers: To plan testing strategies that minimize animal use while ensuring human safety.
• Contract testing laboratories and CROs: To implement standardized in vitro and in vivo irritation assays and produce compliant reports.
• Notified bodies and auditors: To assess conformity of biocompatibility evidence with international expectations.

Related standards and context

• ISO 10993‑1 (biological evaluation framework and risk management) - defines the overall process and how irritation testing fits into device evaluation.
• ISO 10993‑2 (animal welfare and ethical considerations) - provides guidance on animal testing and the 3Rs (replacement, reduction, refinement).
• ISO 10993 series and relevant test method guidance used together to support regulatory submissions and risk assessments.

ISO 10993-23 helps organizations implement robust, reproducible irritation testing strategies-prioritizing validated in vitro alternatives where possible-to demonstrate the safety of medical device materials and products.