Sensitization test – biocompatibility assessment according to EN ISO 10993-10
Medical devices can trigger not only a physical but also an immunological reaction when they come into contact with the human body.
One of these reactions is sensitization, in which the body develops an allergic reaction to the chemical substances or material components contained in the product. The sensitization test – EN ISO 10993-10 is an internationally recognized standard for evaluating whether medical devices can trigger such allergic reactions.
EN ISO 10993-10 is entitled "Biological evaluation of medical devices – Part 10: Tests for skin sensitization". This standard defines the methods used to determine whether delayed hypersensitivity reactions (type IV hypersensitivity) occur in contact with the skin or when it is applied to the body. For MDR (2017/745) and FDA 510(k) applications, this test is required to be performed in accordance with Good Laboratory Practice (GLP) principles.
What is sensitization and why is it tested?
Sensitization is the process by which the immune system develops a "memory" for that substance after the body's first contact with it, and triggers a severe allergic reaction on the second contact. This reaction usually manifests itself in the form of skin redness, swelling, itching and eczema. Substances in medical devices that can trigger such reactions include:
- Plasticizers and stabilizers: Phthalates, epoxy resins
- Metal alloys: Nickel, Cobalt, Chrome
- Latex and rubber components: Natural latex proteins, vulcanization accelerators
- Adhesives and coatings: Acrylates, formaldehyde resins
- Sterilization residues: Ethylene oxide residues
The sensitization test scientifically proves whether the product releases these substances through the skin or systemically to the body and whether it triggers an allergic reaction. Before the test is performed, a chemical characterization of the product (ISO 10993-18) is carried out to determine which substances can be released.
Sensitization test procedure
EN ISO 10993-10 recommends three main methods for assessing awareness. The choice of method depends on the intended use of the product, the duration of contact and the properties of the extract to be tested.
1. GPMT (Guinea Pig Maximization Test)
This is the most commonly used method, which is considered the gold standard. The test is performed on guinea pigs (guinea pigs) by a combination of intradermal injection and topical application. The test substance is mixed with the complete friend adjuvant (FCA) to enhance the immune system's response. After the induction phase, the test substance is administered to the animals again (challenge phase) and the skin reactions are evaluated.
2. Buehler test (closed patch test)
It was developed as an alternative to GPMT. In this method, the test substance is applied to the skin of the guinea pigs in the form of a closed patch. No injection is used. It is particularly suitable for topical products and highly concentrated extracts.
3. LLNA (Local Lymph Node Assay)
This method, performed on mice, measures cell proliferation (proliferation) in the ear lymph nodes using radioactive markers or bioluminescence techniques to determine sensitization potential. As it is more in line with the 3R principles (Replacement, Reduction, Refinement), it is increasingly preferred today. However, it may not be suitable for some device extracts.
Comparison of sensitization test procedures
The following table summarizes the sensitization test methods used under EN ISO 10993-10:
| Method | Animal model | Form of application | Advantages | Cons |
|---|---|---|---|---|
| GPMT | Guinea pig (Guinea Pig) | Intradermal injection + topical patch | High sensitivity, gold standard, widely recognized | Requires more animals, takes a long time (~30 days) |
| Buehler test | Guinea pig (Guinea Pig) | Closed patch (topical) | No injection, suitable for topical applications | The sensitivity can be lower than with the GPMT |
| LLNA | Mouse | Topical (Ear Skin) | Fewer animals, 3R compliant, quantitative results | Use of radioactive substances (for some variants), not suitable for certain substances |
How does the sensitization test procedure work?
Conducting a sensitization test for a medical device requires a careful procedure. This process is designed to reflect the clinical conditions of use of the product:
- 1. Sample preparation and extraction: The product is extracted using polar and non-polar solvents in accordance with ISO 10993-12. As a result, chemicals that could be released from the medical device are transferred to the solution.
- 2. Dose determination: The concentration of the extract is calculated on the basis of the clinical application dose and the surface area of the medical device.
- 3. Induction phase: The test substance is administered to the animals according to the chosen method. This phase ensures that the immune system is sensitized to the substance.
- 4. Challenge phase: After a certain time, the test substance is administered again in low concentrations.
- 5. Observation and evaluation: Skin reactions (erythema and edema) are assessed after 24, 48 and 72 hours. The evaluation is based on the Magnusson and Kligman scales.
- 6. Reporting: Results are documented in accordance with GLP standards. It is indicated whether the product has a potential for sensitization.
GLP Compliant Awareness Testing Services with Nano Test
The biocompatibility assessment of your medical device requires not only a test result, but also documentation of a quality that meets the requirements of regulatory authorities. Nano-Test is your reliable partner in this process with its GLP-compliant sensitization tests according to EN ISO 10993-10.
Nano-Test – Performance Description
Nano-Test offers sensitization tests for medical devices in accordance with EN ISO 10993-10. In our preclinical laboratories, which are accredited according to GLP (Good Laboratory Practice) and ISO/IEC 17025, the methods GPMT (Test for Maximizing the Number of Laboratory Animals), Buehler Test and LLNA (Local Lymph Node Test) are used.
Our service process includes ISO 10993-12 compliant extraction of your product, dose optimization, in vivo testing phases, and histopathological evaluations. All work is carried out in compliance with the approvals of the Ethics Committees for Laboratory Animals and under veterinary supervision. The results are provided as GLP compliance reports with full traceability that you can use for your MDR and FDA 510(k) applications.
At Nano-Test, we not only carry out tests, but also support you in the creation of your biocompatibility strategy (Biological Evaluation Plan – BEP) and provide you with valid data for communication with the regulatory authorities.
Advantages of Nano-Test's Sensitization Test:
- Comprehensive range of methods: All methods – GPMT, Buehler and LLNA – are available.
- GLP-certified infrastructure: All studies are conducted in accordance with GLP principles and ALCOA+ requirements.
- Quick planning: Depending on the device category and contact time, the most appropriate testing strategy will be determined.
- Expert team of veterinarians: The welfare of the laboratory animals and ethical standards are maintained at the highest level.
- Adherence to the 3R principles: Wherever possible, methods such as LLNA are recommended, which require fewer animals.
Sensitization is one of the most common and annoying adverse reactions that can be caused by medical devices.
Sensitization test – EN ISO 10993-10 is a crucial step in scientifically proving whether your product poses this risk. Selecting the right test method, properly performing the extraction, and reporting the results in accordance with GLP standards are prerequisites for the smooth running of the regulatory approval process.
Nano-Test comprehensively meets the sensitization testing needs of medical device manufacturers with its preclinical infrastructure, expert staff, and GLP-compliant processes. Partner with Nano-Test to increase the safety of your product and accelerate market access.