Synthesis and biological evaluation of [I]iodocarvedilol as a potential radiopharmaceutical for heart imaging.

The optimization of the radiolabeling yield of carvedilol with iodine-131 was described. Dependence of the labeling yield of [I]iodocarvedilol on the concentration of carvedilol, chloramine-T content, pH of the reaction mixture and reaction time was studied in details. Carvedilol was labeled with iodine-131 at pH 6 with a labeling yield of 92.6 ± 2.77% by using 100 µg carvedilol, 200 µg chloramin-T (CAT) and 30 min reaction time. The formed [I]iodocarvedilol was nearly stable for a time up to one day. Biodistribution of [I]iodocarvedilol was investigated in experimental animals. [I]iodocarvedilol was located in the heart with a concentration of 19.6 ± 0.41% of the injected dose at 60 min post injection. It has a high heart uptake and heart to liver ratio, both of which are beneficial for high-quality SPECT (single-photon emission computerized tomography) myocardial imaging. [I]iodocarvedilol solve most the drawbacks of the FDA (Food and Drug Administration) approved Tc-sestamibi.