Affinity Assay: The GPIIb/IIIa receptor was immobilized 48 hours at least (100 μL per well, 48 to maximum 96 hours) on a 96-well solid plate (Immuno Plate MaxiSorp™, Nunc, Roskilde, Denmark) at 277 K to 280 K and at a concentration of 0.1 μg per well to 1 μg per well. As negative control one row of the plate (n=8) was incubated just with 2% bovine serum albumin (200 μl per well, albumin from bovine serum−lyophilized powder, ≥96° 0, Sigma, diluted in D-PBS(+)). After washing three times with the wash buffer (230 μL per well, Dulbecco's Phosphate Buffered Saline (D-PBS (−)) contains no calcium or magnesium, GIBCO®, Invitrogen) residual exposed plastic and unspecific binding sites were blocked by incubating the plate with a special blocking solution (200 μL per well, Roti®-Block, Carl Roth GmbH Co KG, Karlsruhe) containing 2% bovine serum albumin (Albumin from bovine serum−lyophilized powder ≥96%, Sigma) 1 hour at room temperature. After washing three times with the wash buffer 50 μL of tritiated reference compound (60 nM, 3H-labeled compound) and 50 μL of novel compound (inhibitor, 19F) were simultaneously added to each well and incubated for 1 hour at room temperature. Several concentrations of each novel inhibitor (0.1, 1, 2, 5, 10, 20 50, 100, 200, 500, 1000, 2000, 5000, 10000 and 20000 nM) were investigated. At each concentration of inhibitor a fourfold determination was performed.