Amyloid PET/CT study in a patient with cognitive impairment being evaluated for Alzheimer’s disease and other causes of cognitive decline shows a high level of tracer binding to amyloid plaques in the brain. Image obtained with Siemens Healthcare's Biograph mCT and evaluated with 510(k)-pending syngo.PET Amyloid Plaque software Source: University of Tennessee

The FDA has approved Amyvid, a radioactive diagnostic agent from Eli Lilly and Avid Radiopharmaceuticals that is indicated for brain imaging of beta-amyloid plaques in patients with cognitive impairment who are being evaluated for Alzheimer's disease and other causes of cognitive decline.

Amyvid is a radioactive diagnostic agent tagged with a radioisotope called fluorine-18. Amyvid binds to amyloid plaques, a characteristic of Alzheimer's disease, and is detected using PET scan images of the brain, according to a Lilly statement. A negative Amyvid scan indicates sparse to no amyloid plaques are currently present, which is inconsistent with a neuropathological diagnosis of Alzheimer's disease and reduces the likelihood that a patient's cognitive impairment is due to Alzheimer's.

Conversely, a positive Amyvid scan indicates moderate to frequent amyloid plaques are present; this amount of amyloid plaque is present in patients with Alzheimer's disease, but may also be present in patients with other types of neurologic conditions and in older people with normal cognition. However, the Indianapolis-based Lilly said that a positive Amyvid scan does not establish a diagnosis of Alzheimer's disease or other cognitive disorders. In addition, the safety and effectiveness of Amyvid have not been established for predicting development of dementia or other neurologic condition, or monitoring responses to therapies.

Amyvid was evaluated in three clinical studies that examined images from healthy adult patients as well as patients with a range of cognitive disorders, including some terminally ill patients who had agreed to participate in a postmortem brain donation program.

Because Amyvid loses over half of its radioactivity every two hours, Amyvid must be distributed directly from a radiopharmacy to the imaging centers where it will be administered within several hours, said the company. Beginning in June, a limited number of radiopharmacies will be distributing Amyvid with the goal of making the product available in more areas as soon as possible.

Amyvid images should be interpreted only by readers who have successfully completed Amyvid reader training, Lilly said. The company added that it has worked with the FDA and nuclear medicine experts to identify the appropriate ways to support accurate and consistent interpretation of Amyvid scans by imaging physicians. These efforts resulted in the development and validation by Lilly of both an online and in-person reader training program for physicians using Amyvid. However, according to Lilly, errors may occur in the estimation of plaque density during image interpretation.

The most common adverse reactions reported in clinical trials were headache (1.8 percent), musculoskeletal pain (0.8 percent), fatigue (0.6 percent), nausea (0.6 percent), anxiety (0.4 percent), back pain (0.4 percent), blood pressure increased  (0.4 percent), claustrophobia (0.4 percent), feeling cold (0.4 percent), insomnia (0.4 percent) and neck pain (0.4 percent).

Also, the pharmacodynamic drug-drug interaction studies have not been performed in patients to establish the extent, if any, to which concomitant medications may alter Amyvid image results.

For full prescribing information, visit http://pi.lilly.com/us/amyvid-uspi.pdf.