So-called "custom" medical devices are much like the compounded versions of pharmaceutical products: made and intended for a single individual based on their particular-and unique-needs. And like properly compounded products, the US Food and Drug Administration (FDA) is looking to clarify the differences between a custom device exempt from most of its regulations and a commercial medical device.

Under existing law, custom medical devices are mostly exempt from regulation under Section 520(b) of the Federal Food, Drug and Cosmetic Act (FD&C Act). For example, custom devices don't have to obtain premarket approval or clearance from FDA, but do need to meet standards for good manufacturing under FDA's quality system regulations (QSR).

The devices are defined as devices not being generally available, not available in finished form, deviated for the needs of a specific patient, not advertised for commercial distribution and intended for a specific patient.

The difference between custom and commercial medical devices has, like pharmaceutical compounding, been subject to much ambiguity and litigation. In April 2009, for example, FDA won a case before the US Court of Appeals for the Eleventh Circuit against manufacturer Endotec, which the court found was manufacturing devices and marketing them as "custom" when they were actually subject to FDA regulation. Though FDA won the case, The Gray Sheet reported that left unanswered by the courts was an important question: What bright line separates a custom device from a commercial one?

The question would go unanswered until 2012, when the FDA Safety and Innovation Act (FDASIA) would amend Section 520(b) to establish specific requirements that a custom device would need to meet in order to be exempted from FDA's approval or clearance requirements.

The existing definition was amended to include some subtle but important changes. The definition of custom medical device now reads:

1. is "created or modified in order to comply with the order of an individual physician or dentist (or any other specially qualified person designated under regulations promulgated by the Secretary after an opportunity for an oral hearing)"
2. must not be "generally available in the United States in finished form through labeling or advertising by the manufacturer, importer, or distributor for commercial distribution"
3. must be for the purpose of treating a "unique pathology or physiological condition that no other device is domestically available to treat"
4. must be manufactured for the "special needs of such physician or dentist (or other specially qualified person so designated) in the course of the professional practice of the physician or dentist (or other specially qualified person so designated)" or by an individual patient named in such order.

FDASIA also put into place additional exemptions and requirements. Manufacturers of medical devices intended to treat rare conditions, for example, are also exempted from premarket approval and clearance regulations to long as they make no more than five units per year of that particular device.

Manufacturers will also be required to submit an annual report to FDA justifying their use of the custom medical device exemption.

But FDA made clear in a recent Federal Register notice that FDASIA marks the beginning, and not the end, of a process for clarity. The agency has been lambasted in some circles for not releasing guidance on the topic or providing clarity to industry. A May 2011 report by the American Academy of Orthopedic Surgeons stipulated that FDA could be holding off on releasing guidance in an attempt to preserve more enforcement flexibility with which to go after manufacturers. Whatever the cause, the Academy report noted industry had largely pulled back from providing custom devices to doctors in the absence of guidance for fear of enforcement action by the agency.

FDA's 19 November 2012 Federal Register notice indicates the agency's hesitancy may be waning.

In the notice, FDA said it is seeking additional clarity on the use of the custom medical device exemption from the public, including members of industry, doctors and patients. Such notices are sometimes an advanced step before the release of draft guidance on a topic.

In particular, FDA says it wants feedback on five areas:

• For which conditions or under what circumstances would patients, manufacturers or doctors find the use of a custom medical device appropriate?
• For which specific rare conditions would manufacturers, patients or physicians use or wish to use a custom medical device?
• Are there areas beyond orthopedic and dental medical devices where the custom device exemption could prove useful?
• What types of information would manufacturers require from physicians or doctors when filling an order for a custom device?
• How often are custom medical devices ordered to accommodate the special needs-i.e. unusual anatomical features-of a physician or doctor?

Comments on FDA's notice are due by 18 January 2013.