Safety, biodistribution and radiation dosimetry of [(123)I]ioflupane in healthy Chinese volunteers

BACKGROUND: [(123)I]ioflupane is a radiopharmaceutical used to visualise the dopaminergic neuron terminals in the striata, to aid in the differential diagnosis among Parkinsonian syndromes (e.g., Parkinson’s disease). However, nearly all of the subjects in the initial development studies of [(123)I]ioflupane were Caucasian. METHODS: 8 Chinese healthy volunteers (HVs) received a single 111 MBq ± 10% dose of [(123)I]ioflupane and had simultaneous whole-body (head to mid-thigh) anterior and posterior planar scintigraphy scans at 10 min and 1, 2, 4, 5, 24, and 48 h. To estimate biodistribution, dosimetry was evaluated for the Cristy–Eckerman female and hermaphrodite male phantoms. Single-photon emission computed tomography (SPECT) images of the brain were acquired at 3 and 6 h after injection. Blood samples and all voided urine were collected for 48 h for pharmacokinetic analysis. The results were then compared with those of a similar European study. RESULTS: There were strong similarities in uptake and biodistribution between the Chinese and European studies. Excretion was primarily renal, and the values were similar for the first 5 h but diverged after that, possibly because of differences in subjects’ height and weight. Tracer uptake in regions of interest in the brain was stable over the imaging window of 3 to 6 h. The difference in mean effective dose for Chinese HVs vs European HVs (0.028 ± 0.00448 vs 0.023 ± 0.00152 mSv/MBq) was not clinically significant. The [(123)I]ioflupane was well tolerated. CONCLUSION: This study demonstrated that a single 111 MBq ± 10% dose of [(123)I]ioflupane injection was safe and well tolerated, and the SPECT imaging window of 3 to 6 h after injection of [(123)I]ioflupane was appropriate in Chinese subjects. Trial registration number ClinicalTrials.gov: NCT04564092.