SYNTHESIS OF [C-11] GRANISETRON, A POSSIBLE POSITRON-EMISSION-TOMOGRAPHY LIGAND FOR 5-HT3 RECEPTOR STUDIES

[C-11] Granisetron, a selective 5-HT3 antagonist, was synthesized by N -alkylation of the desmethyl compound using [C-11] methyl iodide as th e labelling agent in a total synthesis time of 40 min, including semi- preparative HPLC purification. Approximately 40 mCi (1.5 GBq) of the r adioligand was obtained with a specific activity of 200-250 mCi/mu mol (7.4-9 GBq/mu mol). Chemical (greater than or equal to 96%) and radio chemical purity (greater than or equal to 99%) were determined using a nalytical HPLC.