Radioiodination of Quetiapine and Cyclobenzaprine as Brain Monitoring Agents: A Comparative Study on SPECT Imaging

The aim of this study is to use drugs capable of crossing the blood-brain barrier (BBB) to develop new radiopharmaceuticals for non-invasive brain imaging. Quetiapine (QTP) and cyclobenzaprine (CBP), as two 5-HT2A receptor antagonists, were successfully labeled with radioactive iodine (¹²⁵I) using Chloramine-T (CAT) as an oxidizing agent via electrophilic substitution reactions. After studying the parameters affecting the labeling yield, the highest radiochemical yields of ¹²⁵I-QTP and ¹²⁵I-CBP were found to be 94.5 % ± 1.0 and 91.7 % ± 0.6, respectively, at ph 2. The biodistribution and the SPECT/CT image showed that the maximum uptake of radioiodinated-QTP by the mouse brain was 10.2% and 10.9% at 120 minutes post-injection, while the uptake percentages of radioiodinated-CBP were 7.7% and 12.4% at 240 minutes post-injection. The results have shown that radioiodinated-QTP and radioiodinated-CBP are novel radiopharmaceuticals and may be used for brain imaging