When this test applies
Sensitization is required for essentially every device with patient contact under ISO 10993-1:2025. GPMT is the most sensitive of the animal methods in ISO 10993-10:2021 and remains the reference where a submission expects an animal assay, where the material falls outside the applicability domain of the in vitro assays, or where an in vitro result needs confirming.
When to run it
After cytotoxicity, and once the material and its manufacturing process are locked — at 8 to 10 weeks with an induction and a challenge phase, this is not a study to repeat. Consider the in vitro route first: KeratinoSens (GRK-4002-03) is faster and cheaper, and where it covers the material it can remove the need for this study entirely.
What a pass tells you
That skin reactions in the test group were no greater than in the control group — a non-sensitizer under ISO 10993-10. Magnusson-Kligman grades of 1 or more in test animals above the control response are what indicate sensitization, so the control group response is not a formality: it is the baseline the whole result is read against.
What it does not tell you
Sensitization is a distinct endpoint from irritation, and a non-sensitizer can still be an irritant. It also says nothing about cytotoxicity, systemic effects or genotoxicity, and it tests the extracts — not the device surface in direct contact.
Method
Testing per ISO 10993-10:2021 by the guinea pig maximisation test. Two extracts are prepared, one polar and one non-polar, and used for an induction phase followed by a challenge phase; skin reactions are graded against the concurrent control group. 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.
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 8 to 10 weeks by either route.
Usually ordered alongside
Cytotoxicity and irritation as the rest of the baseline battery, and KeratinoSens (GRK-4002-03) where the in vitro route is worth trying first.
