Biocompatibility refers to a medical device’s ability not to trigger unacceptable biological reactions during its intended contact with the body. It is not a material constant, but a product-specific assessment statement: it depends on the material, manufacturing and cleaning processes, sterilization method, the type and duration of body contact, and the intended purpose. The methodological framework is the ISO 10993 series of standards, whose Part 1 explicitly positions biological evaluation as a process within risk management in accordance with ISO 14971 and categorizes products by the type and duration of body contact. From a regulatory perspective, Annex I, Chapter II of Regulation (EU) 2017/745 requires, among other things, assessment of material compatibility, toxicity, leachability, and degradation products. The evidence is consolidated in the biological evaluation report.
Material and chemical characterization
The starting point is full knowledge of the product in its final state: materials of all body-contacting components, including additives, colorants, and adhesives; processing aids such as release agents or coolants/lubricants; residues from cleaning and sterilization; and ageing and degradation behavior. ISO 10993-18 describes chemical characterization for this purpose, typically via extraction studies under exhaustive or simulated conditions followed by analytical identification and quantification of extractable and leachable constituents. The identified substances are then subjected to a toxicological risk assessment in accordance with ISO 10993-17, in which exposure doses are compared with toxicological threshold values. In many cases, this route can replace animal testing; however, it requires robust analytics, correctly selected extraction conditions, and a traceable derivation of exposure from clinical use.
Biological endpoints and test strategy
ISO 10993-1 derives which biological endpoints must be addressed from the categorization of body contact. For almost all products with body contact, these include cytotoxicity in accordance with ISO 10993-5, sensitization in accordance with ISO 10993-10, and irritation or intracutaneous reactivity in accordance with ISO 10993-23. Depending on the type and duration of contact, systemic toxicity, subchronic and chronic toxicity, genotoxicity, implantation response, hemocompatibility, carcinogenicity, and reproductive toxicity may be added; for products with material degradation, degradation products must also be assessed. Crucially, an endpoint must be addressed, but does not necessarily have to be tested: existing data from the literature, predicate devices, raw material dossiers, or the toxicological risk assessment may cover the endpoint. The test strategy is defined in advance in a biological evaluation plan; data gaps are identified with justification and closed; testing should be performed on the sterilized final product or on representative samples.
Distinction from clinical evaluation and sterility testing
Biological evaluation is a preclinical, material- and exposure-related safety assessment; clinical evaluation assesses the device’s performance and safety in use based on clinical data. Both are independent elements of the technical documentation, but they reference each other: results of the biological evaluation feed into the clinical evaluation as preclinical evidence, while clinical observations of local reactions or intolerances, in turn, inform updates to the biological evaluation. Biocompatibility must also be clearly distinguished from microbiological requirements: sterility, bioburden, endotoxins, and packaging integrity are covered by separate standards and address freedom from microorganisms, not material compatibility. Likewise, biological evaluation does not make any statement about mechanical suitability, resistance to ageing, or electrical safety.
Relevance for clinical trials
Before a clinical investigation begins, the biological safety of the investigational device must be demonstrated. Annex XV of Regulation (EU) 2017/745 requires preclinical data, including the results of the biological evaluation, in the application and notification documentation; ethics committees and competent authorities assess whether material safety justifies the exposure of study participants. Unresolved biological endpoints are therefore a frequent reason for follow-up questions or delays and cannot be replaced by clinical observation.
Within the study, findings on local tolerability, inflammatory parameters, explant analyses for implants, and information on contact duration and exposure area provide data that support updating the biological evaluation. Any change to material, supplier, manufacturing process, or sterilization process during the study period requires an assessment of whether biological safety remains demonstrated and whether the investigation plan needs to be adapted. Full-service CROs such as Mediconomics support manufacturers and sponsors in structuring preclinical and biological evidence for study documentation, identifying data gaps prior to submission, and appropriately operationalizing tolerability endpoints in the investigation plan.
Frequently Asked Questions (FAQ)
Does every biological endpoint have to be tested experimentally?
No. ISO 10993-1 requires that every relevant endpoint be addressed. Evidence may also be provided using existing data, literature, material history, or a toxicological risk assessment in accordance with ISO 10993-17; only justified data gaps are closed through testing.
Is a biocompatibility certificate from the material supplier sufficient?
No. The final product is assessed after all manufacturing, cleaning, and sterilization steps. Raw material data are valuable input, but they do not replace the product-specific evaluation.
When does the biological evaluation need to be updated?
In the event of changes to materials, suppliers, manufacturing or sterilization processes, an expanded intended purpose or longer contact duration, as well as new findings from post-market surveillance, vigilance, and the literature.
Regulatory References
- ISO 10993-1:2018 – Biological evaluation of medical devices, Part 1: Evaluation and testing within a risk management process
- ISO 10993-5, ISO 10993-10 and ISO 10993-23 – Cytotoxicity, sensitization, irritation
- ISO 10993-18:2020 and ISO 10993-17:2023 – chemical characterization and toxicological risk assessment
- Regulation (EU) 2017/745, Annex I, Chapter II, Section 10 – chemical, physical and biological properties
- Regulation (EU) 2017/745, Annex II, Section 6.1 and Annex XV – preclinical data in the technical documentation and in study documentation
