The FDA has published guidance on Class II special controls for olfactory test devices. The guidance represents a final rule classifying olfactory (smell) test devices as Class II when used to treat olfactory loss, the FDA said. When used for screening or diagnosis of diseases or conditions other than the loss of olfactory function, the device is not exempt, the agency noted.

Firms that intend to market this type of device do not need to submit a premarket notification to the FDA and receive agency clearance prior to marketing it as a Class II device, although the product must comply with general and special controls, the guidance says.

An olfactory test device is used to determine whether a patient is experiencing loss of smell. The device involves placing odorants under the patient's nose to assess the patient's ability to smell.

The agency recommends performance testing when the devices fail to detect loss of smell and labeling stating the device is meant only to detect loss of smell, the guidance says.

The "Guidance for Industry and FDA Staff -- Class II Special Controls Guidance Document: Olfactory Test Device," can be viewed at http://www.fda.gov/cdrh/ode/guidance/1595.pdf (http://www.fda.gov/cdrh/ode/guidance/1595.pdf).