18F-labelled N,N-dimethylamphetamine analogues for brain imaging studies

The radiochemical yields of nine N,N-dimethyl-2-(substituted phenyl)-isopropylamines (amphetamine analogues) were determined following reaction with [¹⁸F]acetyl hypofluorite in a 0.1 M HCl solution at room temperature. The meta-dimethoxy substituted amphetamines gave the highest radiofluorination yields (24–32%, at EOB). Purification of the ¹⁸F-labelled amphetamines was achieved in 10–20 min. 5-¹⁸F-2,4-Dimethoxy-N,N-dimethylamphetamine (5-¹⁸F-2,4-DNNA) was utilized to determine brain and lung uptake in rats. Positron emission tomography studies were conducted in a dog to determine the dynamic brain uptake and retention of this agent. The 5-¹⁸F-2,4-DNNA exhibited decreased initial uptake and more rapid loss of radioactivity in cerebral tissue compared to the iodinated homologue.