Synthesis and pharmacological evaluation of 99mTc-labeled imidazolyl-containing diphosphonic acid as a novel bone imaging agent.

In order to develop a superior bone imaging agent, a new radiotracer Tc-99m-1-hydroxy-5-(2-butyl-1H-imidazol-1-yl)pentane-1,1-diyldiphosphonic acid (BIPeDP) was designed and prepared with good radiochemical yield and stability. The biodistribution in mice shows that Tc-99m-BIPeDP has high specificity in the skeleton with the maximum uptake of 17.30 +/- 0.14 injected dose per gram at 60min. Kinetics of blood clearance shows that the distribution half-life (T-1/2) and elimination half-life (T-1/2) of Tc-99m-BIPeDP are 3.7 and 49.7min, respectively. An excellent image can be obtained at 1-h post-injection with the single photon emission computed tomography bone scanning, which is clearer and quicker than Tc-99m-zoledronic acid, Tc-99m-1-hydroxy-5-(1H-imidazol-1-yl)pentane-1,1-diyldiphosphonic acid, and Tc-99m-methylenediphosphonic acid All results indicate that Tc-99m-BIPeDP holds great potential as a novel promising bone imaging agent. Copyright (c) 2013 John Wiley & Sons, Ltd.