Figure 2.

Kinetics of binding are only known for a few compounds, and at µM to near mM concentrations (upper right). Representation of the shapes of these curves are illustrated for misonidazole (inverted closed triangles), EF5 (closed diamonds) and etanidazole (closed squares). All drugs tested revert to 1^st order dependence on drug concentration at low oxygen levels (open squares; 0.2%, etanidazole). Shown at many logs lower concentrations are the low and moderate SA ¹⁸F-EF5 (open diamonds), high SA ¹⁸F-FMISO (open inverted diamond) and ¹⁸F-fluoroetanidazole (open square). The only in vitro data in the high SA range is for ¹⁸F-FAZA (open triangle). No current information exists as to whether these extrapolated points mean anything, or what happens between anoxic binding and (for example) 0.2% oxygen (vertcal arrows). Note that this graph spans many decades of concentration for both axes.