Eli Lilly and Co. said late Friday that the Food and Drug Administration approved Amyvid, a diagnostic imaging agent that is intended to help diagnose Alzheimer's disease.
Amyvid is a radioactive imaging agent that binds to beta-amyloid plaques and causes them to show up on positron emission tomography, or PET, scans of the patient's brain. It does not prove that a patient with cognitive problems has Alzheimer's disease and does not completely rule out the condition. Eli Lilly said Amyvid is one tool intended to help find the cause of a patient's cognitive decline.
Doctors diagnose Alzheimer's disease by observing patients and administering physical and mental tests. Researchers said the disease could be diagnosed sooner if they could detect amyloid plaques earlier.
Eli Lilly said a negative scan means no plaques are present, a finding that is not consistent with a diagnosis of Alzheimer's disease. A positive scan indicates the patient has a moderate to high level of plaques. That can indicate the patient has Alzheimer's disease, although the plaques are also present in patients with other neurological conditions and are found in older people with normal cognitive function.
The FDA refused to approve Amyvid in March 2011. The agency told Eli Lilly it needed to create a program to help make sure scans using Amyvid would be interpreted correctly.
Amyvid was developed by Avid Radiopharmaceuticals. Eli Lilly bought Avid for $300 million in 2010.
A definitive diagnosis of Alzheimer's disease is usually made after the patient dies and an autopsy is performed. Lilly said many people who are believed to have Alzheimer's do not actually have the disease.