Flutemetamol (18F)

Flutemetamol (¹⁸F), the active substance in Vizamyl, is a radiolabeled diagnostic agent that binds selectively to β-amyloid neuritic plaques in the brain, a key pathological feature of Alzheimer’s disease. After administration, it crosses the blood–brain barrier and attaches to fibrillar amyloid β deposits, including both cored and diffuse plaques, with negligible binding to neurofibrillary tangles or soluble forms of amyloid β. The fluorine-18 isotope emits positrons, which are detected by positron emission tomography (PET) to visualize amyloid deposition. In vitro studies demonstrated a high binding affinity (Kd ≈ 6.7 nM) and selectivity confirmed by autoradiography and immunohistochemistry, while in vivo data showed a strong correlation between cortical uptake and β-amyloid burden measured in autopsied brain tissue.