Preparation and biodistribution assessment of 111 In-BPAMD as a novel agent for bone SPECT imaging

An early diagnosis of bone metastases is very important for providing a profound decision on a subsequent therapy. In this study, a new agent for SPECT-imaging of bone metastases, 111 In-(4-{[(bis(phosphonomethyl))carbamoyl]methyl}-7,10-bis(carboxymethyl)-1,4,7,10-tetraazacyclododec-1-yl) acetic acid ( 111 In-BPAMD) complex has been developed with specific activity of 2.85 TBq/mmol. Radiochemical purity of the radiolabeled complex was checked by instant thin layer chromatography method indicated high radiochemical purity > 95% at the optimal conditions. The complex demonstrated significant stability at room temperature and in human serum at least for 48 h. Hydroxyapatite (HA) binding assay showed high binding ability of the radiolabeled complex even at the low amounts of HA. Also, log P measurements highlighted the strong hydrophilic nature of the complex. Biodistribution studies as well as planar imaging after injection of the complex into the male Syrian mice showed major accumulation of the labelled compound in the bone tissue. Totally, the obtained results indicated that 111 In-BPAMD has interesting characteristics as an agent for SPECT-imaging of the bone metastases.