Iometopane I-123 is a tropane derivative labeled with iodine-123 that was being developed by MGI GP (MGI Pharma) as an injectable Single-photon emission computed tomography (SPECT) imaging agent. The ability of iometopane to bind to the dopamine transporter on presynaptic dopaminergic nerve terminal in the striatum has been used to differentiate the uptake of the agent by the neurons in the striatum in patients with a Parkinsonian disorder from patients without a Parkinsonian disorder with high sensitivity and specificity. The diminished uptake of iometopane in the striatum on the SPECT images of patients with a Parkinsonian disorder can be applied to assess both disease trait and disease state (severity) reflected by the severity of the brain dopamine neuron loss. Unfortunately Phase III clinical trials and further development of iometopane was discontinued due to the inability to contract a suitable manufacturer for the clinical and commercial supply of iometopane on acceptable conditions in the US. Currently, Iometopane is mainly used in scientific research into the dopamine reuptake transporter.