by Thor Rollins, Biocompatibility Specialist, RM(NRCM)
May 3, 2010
There’s a myriad of tests medical device manufacturers need to be prepared to conduct on their creations in order to pass regulation requirements before they are released to the marketplace. None more important than the Cytotoxicity, Sensitization, and Irritation tests—the Big Three as we call them.
They are the Big Three because they must be conducted on every device before they can be submitted to the Food and Drug Administration (FDA). It is very difficult to get around doing the three tests. Other tests may or may not need to be conducted.
By understanding these three tests, you can be better prepared for submission to the FDA and better prepared to write justifications when the tests indicate a failure. Here is a description of each of the tests:
- Cytotoxicity testing is a very basic, very simple In Vitro test that can begin at any time. Due to its low cost, it can also be done many times throughout the process. It is a test at the cellular level and measures the impact your device has on drawing toxins out of the device. See Cytoxicity: The One Test to Help You Get It Done Right the First Time)
- Sensitization testing is an In Vivo test that looks for delayed hypersensitivity or Type 4 sensitivity. The test determines if your device causes a reaction with repeated exposure. The test looks for a reaction by the immune system. The test takes longer and requires careful planning to avoid additional costs and wasted time.
- Irritation testing is similar to sensitization testing, but it tests Type 1 sensitivity or an immediate reaction to your device. The test allows you to know if the device creates an immediate reaction when it comes in contact with a patient’s body.
It’s important that you gain a clear understanding of these tests so you can look for things that aren’t sensitizers, cytoxic or irritants from the very beginning of the manufacturing process. With just a little background you can:
- Know the importance of each test and why they have to be done. It helps to know what each test is looking for and the acceptance standard for each.
- Get an idea of the potential dangers in each test and what impact your device may have on the test.
- Know what the reaction to the patient may be based on the results of a failed test. Is it something you can justify? Do you need to reevaluate the materials and processes you are using to get it to pass? Can a risk assessment on the toxicity of the device be made or does the toxicity need to be eliminated?
If your device passes the required tests, the FDA process can go more smoothly. But, if it is a complicated device, or there are certain test failures that need to be justified, then the reviewing process can be longer or even bog down.
You need to know about these tests so you can develop products that pass—it allows you to see the impact. If you have a failure then you can make intelligent decisions on what to do with the device whether it is to make adjustments to pass or to make justifications for the failure.