Center for Devices and Radiological Health (CDRH) is the branch of the United States Food and Drug Administration responsible for the premarket approval of all medical devices, as well as overseeing the manufacturing, performance and safety of these devices. The CDRH also oversees the radiation safety performance of non-medical devices which emit certain types of electromagnetic radiation, such as cellular phones and microwave ovens.
CDRH splits medical devices into three classes with different regulatory requirements:
Class 1 includes everyday items such as toothbrushes which are unlikely to cause serious consequences if they fail. Manufacturers are required to follow what are called "general controls" which closely match ISO 9000 requirements.
In addition to the general controls, Class 2 devices require an approval that is referred to as a "510k" after the relevant section of the Food, Drug and Cosmetic Act. The intent of this class was for new manufacturers of devices that already existed when the rules were established. A class 2 device is required to be "substantially equivalent" to existing devices. The class is now used for "medium risk" devices such as demineralized bone powder used for reconstructive surgery, which is officially substantially equivalent to Plaster of Paris, a much older product that was used for the same purpose. This equivalence is used when the FDA does think a full approval process with extensive clinical trials is inappropriate.
Class 3 devices require a "Pre-market Approval" (PMA), which is analogous to the drug approval process with clinical trials and extensive review of the design. Class 3 devices tend to be products such as pacemakers which would cause obvious risk of injury or death if they did not function properly. As with all devices, the manufacturers must follow the general controls.