Synthesis and comparison of 4-[18F]F-ADAM, 2-[18F]F-ADAM, N-Desmethyl-4-[18F]F-ADAM and [18F]F-AFM as serotonin transporter imaging agents

Abstract 4-[ 18 F]F-ADAM ( 1a ), 2-[ 18 F]F-ADAM ( 2a ), N -Desmethyl-4-[ 18 F]F-ADAM (3a ) and [ 18 F]F-AFM ( 4a ) were synthesized in 1.7, 3.9, 2.9 and 0.6% yield (EOS), respectively, in a synthesis time of ∼120 min from EOB. PET studies in rats showed that t he maximum specific uptake ratios of 1a, 2a, 3a and 4a in midbrain were 3.86, 0.73, 0.35 and 2.23, respectively. Thus, in terms of radiochemical yield, specific binding and in vivo stability, 4-[ 18 F]F-ADAM may be the most appropriate SERT imaging agent for human studies.