Production, Quality Control and Pharmacokinetic Studies of ¹⁶⁶Ho-EDTMP for Therapeutic Applications

¹⁶⁶Ho-EDTMP is a major therapeutic agent which is widely used in bone palliation therapy. In this study, a ¹⁶⁶Ho-EDTMP complex was prepared successfully using an in-house synthesized EDTMP ligand and ¹⁶⁶HoCl₃. Ho-166 chloride was obtained by thermal neutron irradiation (1 × 10¹³ ncm⁻²s⁻¹) of natural Ho(NO3)3 samples (specific activity = 3–5 GBq/mg), dissolved in acidic media. The radiochemical purity of ¹⁶⁶Ho-EDTMP was checked by ITLC (>99%) and stability studies in presence of human serum and final preparation were performed. The biodistribution of ¹⁶⁶Ho-EDTMP and ¹⁶⁶HoCl₃ in wild-type rats was checked by scarification. SPECT imaging of ¹⁶⁶Ho-EDTMP was also performed in wild-type rats. A comparative accumulation study for ¹⁶⁶Ho-EDTMP and ¹⁶⁶HoCl₃ was performed for vital organs up to 48h. Significant bone accumulation (>70%) of the tracer in 48h was observed.