Preparation and preclinical pharmacological study on a novel bone imaging agent (99m)Tc-EMIDP.

A novel zoledronic acid (ZL) derivative, 1-hydroxy-2-(2-ethyl-4-methyl-1H-imidazol-1-yl)ethane-1,1-diyldiphosphonic acid (EMIDP), was prepared and labeled with (99)(m)Tc successfully in a high labeling yield and good stability in vitro. The preclinical pharmacological properties of (99)(m)Tc-EMIDP were investigated and compared with (99)(m)Tc-MDP and (99)(m)Tc-ZL. The studies of biodistribution in mice and SPECT bone imaging of the rabbit suggest that (99)(m)Tc-EMIDP has highly selective uptake in the skeletal system and rapid clearance in the soft tissues. The present findings indicate that (99)(m)Tc-EMIDP holds great potential for bone scintigraphy.