Synthesis of 99mTc-DOTMP and its preclinical evaluation as a multidentate imaging agent for skeletal metastases

The convenient synthetic methodology and in vivo stability of the bone-seeking gamma-radiation-emitting compound, (99m)Tc-DOTMP are described in this paper. The radiolabeling efficiency was found to be >97%, and the stability in serum indicated that (99m)Tc remained bound to the chelate, DOTMP, for up to 24 hours. Blood clearance showed a quick washout from the circulation, and biologic half-life was found to be t(1/2)(F) = 25 min; t(1/2)(S) = 6 hours 5 minutes. The LD(50) was found to be 70 mg/kg, as determined by toxicity studies in BALB/c mice. Biodistribution characteristics of (99m)Tc-DOTMP were examined in BALB/c mice. The drug was excreted mainly through renal routes and the accumulation of (99m)Tc-DOTMP in bone was 9.06 +/- 0.75 percent injected dose per gram at 1 hour. Visual image analysis of (99m)Tc-DOTMP was clinically comparable to the interpretation of imaging studies with conventional (99m)Tc-MDP and other phosphonate derivatives. (99m)Tc-DOTMP injected into Balb/c mice showed prominent bone localization and rapid clearance from blood and other organs, thereby making it a promising candidate as a diagnostic pharmaceutical of bone metastases.