Abstract Tetrabenazine (TBZ)(1, 3, 4, 6, 7, 11b-hexahydro-9, 10-dimethoxy-3-(2- methylpropyl)-2H-benzo [a] quinolin-2-one), a vesicular monamine transporter 2 inhibitor, was prepared as a tritium-labeled compound with high specific activity and radiochemical purity. Catalytic hydrogenation of a precursor with the terminal double bond was used to introduce the tritium. This method provides tritium-labeled TBZ with high specific activity ...