In vivo binding of spiroperidol and bromospiroperidol at low drug loadings.

The binding of spiroperidol and bromospiroperidol, in vivo, was studied over a wide range of drug dosages. It was found that while spiroperidol and bromospiroperidol bind selectively in vivo to tissues known to be high in dopamine receptor binding sites, this specificity of binding does not persist at very low doses. Such anomalous binding behavior can have implications for the non-invasive imaging of these drugs.