FDA CRDH has released for comments a draft guidance document indicating “FDA’s initial thinking on technical considerations specific to devices using additive manufacturing, the broad category of manufacturing encompassing three-dimensional (3D) printing.”1 Given the potential impact of additive manufacturing (AM) on future medical devices as well as on an array of high-value product, readers of Controlled Environments will benefit from reviewing the document and should also consider providing comments.
The draft guidance includes issues discussed at an FDA workshop on AM for medical devices that was held at FDA headquarters in Silver Spring, Md., in Oct. 2014. As invited participants to that workshop, we specifically addressed challenges with cleaning and sterilization. Among the issues which are incorporated into the draft guidance, in Section VI(E), are that cleaning and sterilization processes can be more difficult in AM devices than with those produced by traditional (non-additive) means.
A feature of the layer-by-layer process of AM is that complex geometric structures, including engineered porous structures, tortuous internal channels, and internal support structures can be constructed by AM that would not be possible or practical using traditional approaches. These complex structures can challenge cleaning and sterilization.
For example, non-additive build devices traditionally have been machined and cleaned before entering a cleanroom for final processing. An external porosity, needed to achieve effective tissue adhesion to the implanted device, would be added as a coating after post-machining cleaning. With AM, such porosity can be built in as part of the initial printing, and will therefore be present before any post-printing processes. This can result in higher soil loading in porous structures created by AM, with a consequential higher burden on cleaning and sterilization.
The complex internal structure of some additive devices may result in challenging cleaning processes and may increase the difficulty of verifying/validating cleanliness and sterilization. The internal structure, that may include residues of the powder used in the AM fusion process as well as other contaminants from printing or post-printing processes, may be more difficult to access for the application and removal of cleaning and sterilization agents. For similar reasons, verification/validation of cleaning or sterilization may also be difficult. Validation may therefore require destructive testing.
AM is beneficial in that patient-specific devices can be produced. This brings up the issue of how far validations can be extrapolated. Demonstrating cleaning and sterilization on one device may not be sufficient to validate another somewhat similar yet still unique device. Verification that requires destructive testing could, taken to extremes, result in at least two copies of each device be made, one for final use and others for verification. This would impact both the time to build and economics of patient specific AM devices.
To assure that the FDA considers comments before it begins work on the final version of the guidance, the request is to submit either electronic or written comments by Aug. 8, 2016.2
1. “Technical Considerations for Additive Manufactured Devices, Draft Guidance for Industry and Food and Drug Administration Staff”: http://www.fda.gov/downloads/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/UCM499809.pdf
Barbara Kanegsberg and Ed Kanegsberg (the Cleaning Lady and the Rocket Scientist) are experienced consultants and educators in critical and precision cleaning, surface preparation, and contamination control. Their diverse projects include medical device manufacturing, microelectronics, optics, and aerospace.