When this test applies
ISO 10993-1:2025 flags systemic toxicity for devices with prolonged (24 h to 30 days) or long-term (over 30 days) body contact. The 28-day repeated dose sits at the top of the subacute range and is the study most often expected where contact is long-term or permanent. The dual route is what makes it defensible: a polar and a non-polar extract cannot both be given by the same route, so dosing each by the route its vehicle allows means the whole extractables profile — water-soluble and lipid-soluble alike — is actually administered, rather than only the fraction a single vehicle can carry.
When to run it
Late, and only once the material and its manufacturing process are locked, because a formulation change invalidates the study. Cytotoxicity, sensitization and irritation should be clear first, and chemical characterisation should come before it: at 10 to 12 weeks and 56 dose portions this is among the largest commitments in the battery, and an ISO 10993-17 toxicological risk assessment built on good chemistry routinely removes it from a programme. If it is required, confirm the 28-day duration against your actual contact duration before commissioning — the 14-day study (GRK-4004-03) is the tier below.
What a pass tells you
That across 28 consecutive days of dosing, by both routes, there were no toxicologically significant differences between the test and control groups in clinical signs, body weight, food consumption, clinical pathology, organ weights or histopathology — assessed per ISO 10993-11.
What it does not tell you
Nothing about exposure beyond 28 days; chronic toxicity is a separate, longer study. Nothing about local effects at an implant site, genotoxicity or sensitization, each of which is its own endpoint. And the result is only as complete as the extraction behind it: a constituent that neither the polar nor the non-polar vehicle recovers is not assessed here, which is why the chemistry should be understood first.
Method
Testing per ISO 10993-11:2017. Two extracts are prepared at 18 mL per extract, one polar and one non-polar per ISO 10993-12, giving at least 56 discrete dose portions — one of each extract on each of the 28 days. Extraction ratio follows ISO 10993-12: 6 cm²/mL for material under 0.5 mm thick, 3 cm²/mL at 0.5 mm or thicker, or 0.1 to 0.2 g/mL where surface area is indeterminate. The polar extract is administered intravenously and the non-polar extract intraperitoneally, because a non-aqueous vehicle is not suitable for intravenous administration. Dosing is in the rat (preferred) or mouse, daily for 28 days, followed by terminal clinical pathology, organ weights and histopathology against a concurrent control group.
Choosing a source
This method is available both domestically sourced and internationally sourced. Domestic shortens shipping and simplifies chain-of-custody documentation; international is generally the lower-cost route. Both laboratories are ISO/IEC 17025 accredited and GLP certified, and either report is issued under Groenakker cover, in Groenakker’s report template or in your document template on request at no extra cost. Turnaround is 10 to 12 weeks by either route.
Usually ordered alongside
Acute systemic injection (GRK-4004-02) and material-mediated pyrogenicity (GRK-4004-01) where those endpoints are also open — pyrogenicity is a distinct endpoint rather than a subset of this one. Chemical characterisation and an ISO 10993-17 assessment normally precede it and can change whether it is needed at all. Where contact is prolonged rather than permanent, the 14-day study (GRK-4004-03) may be sufficient.
