A Novel 99mTc-labeled Diphosphonic Acid as Potential Bone Seeking Agent: Synthesis and Biological Evaluation

A novel zoledronate derivative, 1-hydroxy-4-(2-butyl-1H-imidazol-1-yl)butane-1,1- diyldiphosphonic acid (BIBDP) was prepared and labeled with 99mTc successfully in a high radiochemical purity and good stability in vitro. The biodistribution in mice shows that 99mTc-BIBDP has high specificity and efficacy in bone uptake with a maximum of 12.14 ± 0.53 %ID/g at 120 min. Kinetics of blood clearance showed that distribution half life (T1/2α), elimination half life (T1/2β) and total clearance rate (CL) of 99mTc-BIBDP were 4.67 min, 91.9 min and 1.21 %ID/g·min-1, respectively. Moreover, 99mTc-BIBDP has higher uptake in the bone and faster clearance from soft tissues than 99mTc-MDP and 99mTc-ZL. A plain and clear bone image was obtained at 1 h with SPECT bone imaging. The present findings indicate that 99mTc- BIBDP holds great potential for bone imaging.