Extractable/leachable chemistry testing can save, time, money, and animal life for certain classes of devices.

Matthew R. Jorgensen, PhD

Over the past decade, regulatory bodies have shifted their evaluation of biocompatibility from a strict linear approach to a less linear approach that includes in vitro tests and assessment using chemistry. Chemistry has the advantage of providing detailed information on the identity and amount of substances that can leave devices, while traditional biocompatibility tests are pass or fail.

The challenge with chemistry can be that a deeper understanding of device materials and the science of extractable/leachable testing is required to correctly interpret results. Fortunately, for those companies without expertise in using chemistry to fulfill regulatory requirements, help is available through consulting services. The following are three frequently asked questions when consulting on these matters.

When should I consider extractable/leachable chemistry testing?

Extractable/leachable chemistry testing can save time, money, and animal life for certain classes of devices. Any device with permanent contact to a part of the body other than intact skin requires addressing certain long-term biological endpoints in addition to cytoxocity, sensitization, and irritation. Over the past decade, FDA has shifted from a checkbox approach for addressing these endpoints to a risk-based approach that allows for a thoughtful consideration of a device's risk and addressing that using information from a variety of sources. Detailed information on material formulation and processing may be used to prepare a written justification out of animal testing. When information of sufficient detail is not available, extractable/leachable chemistry testing can be used.

At what stage in device development should I think about extractable/leachable chemistry testing?

Extractable/leachable chemistry testing is typically used to avoid more costly and longer duration animal tests. Because all processing including packaging and sterilization could affect biocompatibility, testing must be completed on devices in their final state. While extractable/leachable chemistry testing is faster than several longer duration animal tests, the turnaround time can still be several weeks, depending on demand. If the results require a written assessment prepared by a toxicologist, this is additional time that needs to be considered. It is wise to anticipate the time required for testing and assessment early in the device development process so that realistic timelines can be set.

I am considering changing the color of my device, what should I do?

Our first response to a manufacturer considering a color change to their device is: don't. Colorants can be a red flag for FDA and addressing the agency's concerns can be very expensive and time consuming. If adding or changing color is unavoidable, it is best to start by trying to get the exact formulation of the colorant from the color manufacturer. It is possible to identify a single component of the dye to test for using a limited extractable/leachable chemistry testing approach, and then calculate the concentrations of the other dye components in a written assessment.

Extractable/leachable chemistry testing can save time, money, and spare animal life while providing data relevant to device biocompatibility with a level of detail unavailable using traditional tests. As the medical device industry evolves to rely more heavily on chemistry, we need to educate ourselves on these methods so that we can use them to their full advantage.

Matthew R. Jorgensen, PhD, is a chemistry and materials scientist with Nelson Laboratories. Reach him at [email protected].