Simple Generator for Radiohalogenated Spect Agents

A simple generator system to facilitate the production of SPECT agents is proposed. The radioligand to be used to demonstrate feasibility of this approach is beta-CIT (2beta-Carbomethoxy-3beta¿iodophenyltropane), a compound with high affinity for dopamine reuptake sites in human brain, which is useful in diagnosing and monitoring the progression of Parkinson's disease. The generator will consist of a solid support (polystyrene or agarose) to which a beta-CIT precursor is covalently attached by means of an alkyl tin linker chain. When a solution of electrophilic iodine (I2) is passed through this solid phase, electrophilic iododestannylation will occur, releasing the iodinated ligand. Since unreacted precursor remains attached to the solid support, this technology should produce carrier free beta-CIT that will not require HPLC purification before use. Oxidation of I- to I2 will occur within the generator. If successful, this product will greatly simplify the production of radioiodinated beta-CIT, thereby making this agent more readily available to SPECT centers worldwide. Additionally, the technology could be extended to other SPECT agents that currently require specialized chemical expertise to produce.