Animal studies of 99mTc-i-PIDP: a new bone imaging agent

This study was to investigate the preparation and biodistribution of (99m)Tc-labeled novel zoledronic acid derivative 1-hydroxy-2-(2-isopropyl-1H-imidazole-1-yl) ethylidene-1,1-bisphosphonic ((99m)Tc-i-PIDP) as a potential bone imaging agent. Satisfactory labeling results (radiochemical purity over 95%) were obtained when the amount of i-PIDP, Na(99m)TcO(4), and SnCl(2)·2H(2)O, were 5 mg, 37 MBq, and 100 μg, respectively, the pH value was between 4.0 and 6.0, and the labeling reaction continued for 30 min. The labeled complex was stable at least up to 6h in vitro. The biodistribution and pharmacokinetics studies in mice and single photon emission computed tomography (SPECT) bone scan in rabbit of (99m)Tc-i-PIDP were systematically studied. The results showed that the bone uptake is up to 9.63%ID/g at 60 min after injection of (99m)Tc-i-PIDP. The pharmacokinetic studies indicate that the data can be fitted to a two-compartment model with the equation of C=5.80e(-0.20t)+2.66e(-0.01t). A plain bone image was obtained at 1 h. All of the results suggested that (99m)Tc-i-PIDP is worthy of future investigation as a novel bone imaging agent.