N-(3-Fluoropropyl)-2β-carbomethoxy-3β-(4-[123I]iodophenyl)nortropane

Excerpt

Dopamine, a neurotransmitter, plays an important role in the mediation of movement, cognition and emotion. Parkinson’s disease (PD) is associated with a loss of dopamine-containing neurons in striatum, resulting in a loss of dopamine transporters (DAT) in the presynaptic nerve terminals (1, 2). Reduction of DAT density is inversely correlated with the severity of motor dysfunction in PD patients. Several cocaine analogs were developed for the evaluation of DAT density in neurons of PD patients. Radiolabeled 2β-carboxymethoxy-3β-(4-iodophenyl)tropane (β-CIT) and N-(3-fluoropropyl)-2β-carbomethoxy-3β-(4-iodophenyl)nortropane (FP-CIT) have been used for brain imaging (3-6). Because of the short physical half-live of [¹¹C] of [¹¹C]-analogues, equilibrium conditions are difficult to achieve in positron emission tomography (PET) measurements. [¹²³I]β-CIT was studied in single photon emission computed tomography (SPECT), showing slow tracer uptake kinetics (7, 8). It took 20 to 30 h to reach a stable level in the striatum. Therefore, [¹²³I]FP-CIT was developed for SPECT brain imaging in PD patients (4). [¹²³I]FP-CIT was approved by the United States Food and Drug Administration (FDA) for detecting loss of functional nigrostriatal dopaminergic neurons by SPECT imaging in patients presenting with symptoms or signs suggestive of dopaminergic neurodegeneration in 2011.