Justification for not conducting biocompatibility tests

[guilhermegf]

Hi there,

I'm working on a medical device that uses a light source to treat dermatological conditions and thus has no direct contact with the patient. However, as this light heats the skin of the patient, we also developed a cooling system: we deliver air to the skin through a path composed of a muffler, an oilless air pump, odontological air filter, some silicone and polyurethane (PU) tubing and tube coupling, and stainless steel nozzles. Then, the device has an indirect contact and I don't think that the ISO 18652 applies (not a breathing gas). We are intending to apply for a 510(k) but our predicates do not have (or at least do not mention) any cooling system, which we find awkward, but as this is the case, FDA might take special attention to this point.

Following the ISO 10993 Matrix, we concluded that we are at the absolute lowest risk possible since we have limited indirect contact (<24h) with intact skin. Also, the eSTAR document requests us to perform (or at least justify why we did not) Cytotoxicity, Sensitization and Irritation. We are currently not considering making the tests, but a little afraid of what the FDA might think about it. Did anyone have a similar experience? What steps did you take?

Other main questions regard:

1. Does anyone have suggestions on how to justify this omission of the tests?
2. As we have an odontological (dentist) air filter, could we ignore the parts before it? Although they are an ABS muffler (common material), an oilless air compressor and silicone tubes (this latter only has a certificate for irritation and skin sensitization).
3. We have not found a scientific study to help us with the PU tubing. Do you guys have anything that could support our justification for not performing the tests?
4. For contact with the operator (user), we did only use 304 stainless steel, ABS plastic, and glass on the touchscreen interface. Will the note below be a strong argument?
   "NOTE Some medical devices used in either sterile or non-sterile environments include components that can come into contact with a user’s ungloved hands such as human interfaces for electronic equipment (e.g. computer keyboards, dials or buttons, [...] If these types of components can be shown to be made from materials in common use for other consumer products with a similar nature of contact, no further biological evaluation is needed."

Thanks in advance!
Guilherme

 

[Ed Panek]

When the FDA receives a submission they will build the review team based upon the product code. If there are biocompatibility questions FDA assigns their expert to the review team. Reviewers are dealing with dozens of simultaneous submissions and the one that appears clear to you is just another device to them full of unknowns.

Based on my experience with our medical devices the FDA is unlikely to appreciate any argument unless the author has a few letters behind their name like Ph.D. If the FDA questions your argument I guarantee they will have a Ph.D. Biocompatibility expert on their side. Arguing against a test is fine but if you are what FDA considers a novice in the subject area they might push back. I suggest contacting 10993 lab and recruiting their help and drafting a formal letter. In fact, during your initial call with them (FREE!), they will tell you if your argument holds water or not. PM me for our lab contact.

 

[planB]

ad (1) & (2):
ISO 10993-1:2018 does indeed allow you to justify omission of testing for the endpoints you mentioned, provided that you have adequate material characterization data, such as detailed (technical and safety) material data sheets, including additives and colourants: information such as "some silicone" will most probably not be sufficient: in case you can draw a conclusion from these data that no (volatile) substances of concern are released, you may be in a position to build your case of no-testing. Design features, such as your air filter and your oilless pump will further support your conclusion.

ad (3) & (4)
Yes, the note you referenced, should be an argument, together with a recent FDA draft guidance "Select Updates for Biocompatibility of Certain Devices in Contact with Intact Skin" that says:

Many devices have intact skin contacting materials that are made from polymers and fabrics. FDA believes that these materials pose a very low biocompatibility risk because they have a long history of safe use in medical devices that contact intact skin. For such devices, significant FDA review resources are expended to obtain sufficient rationales to justify omission of biocompatibility testing for frequently used intact skin contacting medical devices, consistent with FDA’s recommendations in the 2016 Biocompatibility Guidance. This Attachment describes a least burdensome approach for these devices that recommends specific material information to be included in a premarket submission in lieu of biocompatibility testing.

PU is listed as an "exempted" material therein.

HTH,