Medical technology network concept.

You’ve done the research, developed the technology, and produced something that could help people, even change lives.

You’ve also figured out that your product is what the Food and Drug Administration (FDA) calls a medical device. That puts you on one of four regulatory pathways for bringing your device to market:

    • Premarket Notification (PMN), often referred to as 510(k): On this pathway, your device is cleared based on its substantial equivalence to a predicate device (that is, a device that’s already on the market). We’ll cover substantial equivalence and predicate devices in detail below.
    • Premarket Approval (PMA): This pathway is for devices that pose a greater risk to users and are not eligible for a 510(k) submission. Bringing a medical device to market under PMA is significantly more resource-intensive than doing so via the 510(k) pathway because of the need to prove the device’s safety and efficacy through a clinical trial.
    • Exempt devices: Devices exempt from the 510(k) and PMA processes only need to satisfy the FDA’s general controls (and special controls, if applicable). This is the quickest and easiest path for bringing a medical device to market.
    • De Novo clearance: Suppose no legally marketed predicate can be found for your device. By default, you must follow the rigorous PMA process, even if your device does not pose a high risk to users. A De Novo submission requests that the FDA classify your device as needing only general and special controls, providing a legal path to market.

Which regulatory pathway is suitable for your medical device? That’s determined by the classification of your medical device.

  • Class I devices may be exempt from the 510(k) and PMA processes; otherwise, they require a 510(k) submission.
  • Class II devices generally require a 510(k) submission.
  • Class III devices generally require a PMA submission.

You can find the appropriate classification for your device by searching the FDA database. Alternatively, you could use Path Surveyor, a free tool provided by in2being. With Path Surveyor, you can determine your device’s FDA classification and identify potential predicate devices.

If your research indicates that your medical device is a Class II device and you’ve identified one or more potential predicate devices, your way forward to FDA clearance is most likely through a 510(k) submission.

The success of your 510(k) submission hinges on demonstrating substantial equivalence between your new medical device and a predicate.

What is a predicate device? A predicate device is:

  1. Already legally on the market
  2. Has the same intended use as your device
  3. Uses the same technology as your device—or at least doesn’t raise new questions of safety and efficacy due to technology. We’ll cover this in more detail below.

What is substantial equivalence? It’s the principle by which you show that your new medical device is safe and effective when you compare it to a predicate.

510(k) Substantial Equivalence

Of the pathways to regulatory clearance available to medical device developers, 510(k) clearance is provided by the FDA as an easier route than PMA and De Novo.

  • PMA and De Novo submissions require a developer to use objective clinical data to prove the safety and efficacy of a device.
  • With a 510(k), the FDA is still concerned with safety and efficacy but doesn’t require you to prove it independently. They allow you to prove it by comparing your device with a legally marketed (i.e., already approved) device similar to your device in terms of technological features and intended use. The FDA calls this a “predicate device.”

Essentially, your 510(k) is a detailed comparison between your device and a predicate device that aims to convince the FDA that your device is substantially equivalent to the predicate device and, therefore, safe and effective.

How Does the FDA Define Substantial Equivalence?

The FDA provides voluminous guidance for preparing a 510(k). The official guidance from the FDA on substantial equivalence lays out the following criteria (originally defined in the Federal Food, Drug, and Cosmetic (FD&C) Act)for determining the substantial equivalence of a new medical device to an existing predicate device.

A new device is substantially equivalent to a predicate device if, compared to a predicate device:
The device has the same intended use OR The device has the same intended use
has the same technological characteristics. has different technological characteristics
AND the submission proves:
1. The device is as safe and effective as the predicate device.


2. The device doesn’t raise different questions of safety and effectiveness than the predicate device.


The pathway outlined on the right-hand side of the chart most likely requires submitting scientific or clinical data to prove items (1) and (2).

The FDA considers that a new device has different technological characteristics if “there is a significant change in the materials, design, energy source, or other features of the device from those of the predicate device.”

When Is It Necessary to Prove Substantial Equivalence?

Proving substantial equivalence is necessary when seeking regulatory clearance for a medical device through a 510(k) submission. Substantial equivalence is not necessary for a PMA or De Novo submission or for an exempt device.

Why? Because the FDA determines the safety and efficacy of new medical devices differently for 510(k) and PMA submissions.

  • In a PMA submission, safety and efficacy are proven using independent clinical data obtained by the developer.
  • In a 510(k) submission, safety and efficacy are proven by demonstrating substantial equivalence to an existing, legally marketed medical device.

What’s the Point of Substantial Equivalence?

Substantial equivalence is used specifically and only with a 510(k).

  • If you’re not pursuing regulatory clearance through a 510(k), you don’t need to show substantial equivalence to a predicate device.
  • If you are pursuing regulatory clearance through a 510(k), demonstrating substantial equivalence is the purpose of your submission. A 510(k) premarket notification proves that a new medical device is safe and effective by establishing the new device’s similarity—substantial equivalence—to a preexisting, legally marketed predicate device.

Predicate Device FDA Meaning

We’ve already discussed predicate devices, but how does the FDA define a predicate device? The FDA guidance on substantial equivalence in 510(k) submissions says:

A predicate device is “a legally marketed device” that:
“was legally marketed prior to May 28, 1976” and does not require a PMA
“has been reclassified from Class III to Class I or II”
has been found to be substantially equivalent through the 510(k) process.

How Substantial Equivalence and Predicate Devices Fit into Your 510(k) Submission

Any device that requires a 510(k) must show substantial equivalence to a predicate device. Whether your device requires a 510(k) is determined by its classification.

  • Class I devices require a 510(k) unless they are exempt.
  • Class II devices generally require a 510(k).
  • Class III devices require a PMA, not a 510(k).

If you determine that your new device belongs in Class I or Class II but cannot find a suitable predicate device, you cannot use a 510(k). Furthermore, the FDA automatically considers such devices to be in Class III and subject to the PMA process. If this is your situation, you should probably consider filing a De Novo request. If your De Novo request is successful, the new device’s safety and efficacy can be established using the FDA’s general and special controls alone, and a PMA is not required.

Determining Substantial Equivalence to a Predicate Device

Medical device substantial equivalence can only be determined using a predicate device. Because of this, the predicate you select is extremely important to your 510(k) submission.

Let’s take a look at some of the characteristics you should consider.

Intended Use of Device

By law (per the FD&C Act), a predicate device must have the same intended use as the new device covered in your 510(k) for the FDA to declare it substantially equivalent.

The FDA defines intended use as “the general purpose of the device or its function.” FDA guidance also indicates that intended use includes “indications for use.”

The term indications for use is defined as “the disease or condition the device will diagnose, treat, prevent, cure or mitigate, including a description of the patient population for which the device is intended.”

In determining intended use, the FDA reviews the proposed labeling for the new device that is included in your 510(k) submission, including information regarding indications for use. In some instances, the FDA may decide that new indications for use mean that the new device is not substantially equivalent to the predicate device. The basis for such decisions is the FDA’s conclusion that the new indications for use raise new questions of safety and efficacy.

Technological Characteristics

If the FDA agrees that your new medical device and the predicate device in your 510(k) have the same intended use, they’ll proceed to evaluate whether the two devices share the same technological characteristics.

The FDA will examine the information you provide on technological characteristics in your 510(k) to determine whether any technological differences between the two devices bring up issues related to safety or efficacy that are not relevant to the predicate device.

Performance Data Requests

Your 510(k) will include clinical and/or nonclinical testing data. The general and/or special controls for your device type will help you determine what kind of testing is necessary for your device. In many instances, the FDA may request additional clinical or nonclinical testing data to corroborate your device’s performance as described in your product labeling and elsewhere in your 510(k).

510(K) Summary for Predicate Devices 

Although your new device and your chosen predicate device don’t have to be identical, finding a predicate that’s as close as possible to your device is helpful. As you prepare your 510(k), emphasize the similarities between your new medical device and the predicate. Remember, the goal is to prove the substantial equivalence of your device and the predicate.

The basic content of a 510(k) is the same for any device. Still, the FDA has put out guidance documents for many subcategories of devices that spell out the type of data necessary for specific device types. If you’re preparing a 510(k), it’s advisable to see if your device is covered under any such device-specific FDA guidance.

What Goes Into a 510(k)?

Within fifteen calendar days of receiving your 510(k) submission, the FDA will conduct a preliminary review using what the agency refers to as a “refuse to accept” checklist. The purpose of the “refuse to accept” review is to ensure that your application includes all the elements necessary for a substantive review.

A 510(k) submission is not a form you fill out; it’s an organized, systematic presentation of your device and its substantial equivalence to a predicate device. The required contents of a 510(k) are as follows:

  • A cover letter with the information specified in the FDA guidance document
  • A table of contents with page numbers for each section and a list of attachments and appendices
  • The 510(k) acceptance checklist appropriate to the type of 510(k) you’re submitting (traditional, abbreviated, or special)
  • A statement of the intended use and indications for use for your device
  • A summary of the information you’re using to claim substantial equivalence
  • A statement certifying the truth and accuracy of your submission
  • The proposed labeling for your device—device labels, package inserts, manuals or instructions for use, and advertising materials
  • Device specifications, including a written description of your device and diagrams, photos, illustrations, and engineering drawings (consult any FDA device-specific guidance for more details regarding what to include)
  • A comparison of your device with the predicate device to establish substantial equivalence, including a discussion of similarities and differences between the two and a clear comparison table
  • Performance data from clinical and/or nonclinical testing
  • Any additional information required by the FDA (e.g., specific requirements based on your device type or features of your device)

What Happens if a Device is Determined to Be Not Substantially Equivalent?

If your 510(k) results in a determination of “not substantially equivalent” (NSE), you’ll need to expend significant time and resources to revise and resubmit your 510(k), perhaps with a different predicate.

The FDA maintains an establishment registration and device listing database that contains information on medical device manufacturers and medical devices listed with the FDA. The database is a great place to start your search for a predicate and to find predicate device examples.

  • If you know the product code associated with your medical device, you can search by product code to find devices that may be suitable predicates for your device.
  • If you know of a product that may be a good predicate for your device, you can also search by manufacturer or product name.

Reach Out to in2being for 510(k) Regulatory Guidance

At in2being, our goal is to help you get your product to market. The direct impact that medical devices have on people’s lives has a dual effect—it means that your device can make a positive difference, but it also means that regulatory oversight is necessary.

If your path to market clearance is through a 510(k), it’s easy to get bogged down in the details. You’re an expert in your own technology, but navigating the regulatory world of the FDA is another matter altogether. We can fill in any gaps in your knowledge, guiding you through the regulatory morass and getting your product to market.

Our goal at in2being is to bring your medical device into being. Contact us today for more information about our regulatory clearance services.

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