High-affinity (K_i1=1.0 nM) and low-affinity (K_i2=65 nM) binding sites have been identified for florbetapir in brain tissue from the frontal cortices of patients with Alzheimer's disease (AD).3

Although the exact binding site of florbetapir F 18 on β-amyloid plaques is unknown, the binding of florbetapir F 18 to amyloid beta (Aβ) aggregates was demonstrated in postmortem human brain sections using

• autoradiographic methods, thioflavin S, and traditional silver staining correlation studies, and
• monoclonal antibody Aβ-specific correlation studies.2,4

Florbetapir F 18 autoradiography (ARG) was performed on sections of postmortem human brain tissue from 40 older subjects with or without AD or other age-related pathologies.4

The intensity of ligand signal was found to correlate with

• Aβ deposition (Correlation Coefficients and P Values for Measures of Florbetapir F 18 Binding and Scores of Plaques or Neurofibrillary Tangles in 16 Brain Tissue Samples), and
• β-amyloid plaque density as identified via Bielschowsky silver stain, thioflavin S, and immunohistochemical measurements of 3 Aβ antibodies (10D5, 6F/3D, and 4G8) recognizing different epitopes of the Aβ peptide (Correlation Coefficients and P Values of Aβ Density Evaluated by Bielschowsky Silver Staining, Aβ IHC, Thioflavin S Fluorescence Microscopy, and Florbetapir F 18 ARG Signal Intensity in 22 Brain Tissue Samples).4

Florbetapir F 18 binding to tau protein and a battery of neuroreceptors was not detected in in vitro studies.2