Posted 09 May 2016
By Michael Mezher
The US Food and Drug Administration (FDA) has released a new draft guidance for medical device manufacturers working with additive manufacturing (AM), which is more commonly known as 3D printing.
In March, FDA approved the first-ever 3D printed drug, Aprecia's epilepsy drug SPRITAM, which relies on 3D printing technology to rapidly disintegrate in a patient's mouth, making it easier to swallow. For biologics, researchers are looking into 3D printing as a means of manufacturing cell and tissue products.
However, for medical devices, 3D printing technology is much farther along. So far, FDA has cleared more than 85 applications for 3D printed devices, though none have been for high-risk devices requiring premarket approval.
According to FDA, the "leap-frog" draft guidance is meant to provide manufacturers with the agency's initial thinking about the technical considerations for manufacturing 3D printed devices, as well as its thoughts on characterizing and validating such devices.
Specifically, FDA says its new guidance covers considerations for two major areas of medical device development: design and manufacturing, and device testing, which includes characterization, validation and verification. However, FDA says the guidance is not intended to address 3D printed products containing biologics, cells or human tissues, and cautions that "point-of-care device manufacturing may raise additional technical considerations" not covered in the draft guidance.
While additive manufacturing (AM) is a relatively new technology, FDA says it holds a number of advantages over traditional manufacturing processes for certain device applications.
"AM has the advantage of facilitating the creation of anatomically-matched devices and surgical instrumentation by using a patient's own medical imaging. Another advantage is the ease in fabricating complex geometric structures, allowing the creation of engineered porous structures, tortuous internal channels, and internal support structures that would not be easily possible using traditional (non-additive) manufacturing approaches," FDA writes.
However, FDA says that additive manufacturing also poses unique challenges when it comes to device characterization, validation and verification.
FDA says it wrote the draft guidance on the basis of feedback it received from a 2014 public workshop on challenges related to 3D printing. Some of the major takeaways from the workshop include the importance of material control, the impact of the 3D printer and post-printing processes on final device performance and the need for a "robust process validation and acceptance protocol."
Design and Manufacturing
As with most types of medical devices, FDA says it expects devices manufacturing using additive manufacturing techniques to adhere to quality systems requirements in order to ensure devices perform as intended.
But because there are multiple additive manufacturing technologies, printers and materials, FDA says it is important for manufacturers to "clearly identify each step in the printing process… from the initial device design to the post-processing of the final device."
FDA also says that companies should make sure they understand the upstream effects different steps in manufacturing process might have on a device.
"For example," FDA writes, "the ratio of recycled to virgin powder can affect melting properties, which affects the energy needed to create consistent bonding between layers, which in turn affects [a device's] final mechanical properties."
Testing and Validation
For device testing, FDA says the data required to support an approval will be based on a device's "intended use, risk profile and classification," and will vary depending on whether the device is implantable or made custom for each specific patient.
For custom, "patient-matched" devices, FDA says manufacturers should specify a range of dimensions for a given device that encompasses all possible sizes that could be produced.
In general, FDA says that 3D printed devices should be tested for the same performance characteristics as non-3D printed devices. However, FDA says that mechanical testing for 3D printed devices should take into account a device's build orientation relative to the 3D printer.
"Since mechanical properties of the device may be impacted by orientation and location, it is important to ensure that production processes are properly developed, conducted, controlled, and monitored to ensure devices or components are not adversely affected by fabrication orientation," FDA writes.