The physical and chemical characteristics of ¹⁷⁵Yb-EDTMP labelled compound

Bone pain is a common complication for patient with bone metastases from breasts, prostate and lung cancers. The derivative of phosphonate groups, i.e. diphosphonate as well as poly phosphonate ligands e.g. EDTMP have high affinity in bone matrix. The labeled compound of ¹⁷⁵Yb-EDTMP can be used as an alternative radiopharmaceutical for bone pain palliation. The compound of ¹⁷⁵Yb-EDTMP can be produced by labeling of ethylenediamine tetramethylene phosphonic acid (EDTMP) with itterbium-175 (¹⁷⁵YbCl₃). Before ¹⁷⁵Yb-EDTMP is used for bone pain palliation in nuclear medicine, the compound have to be characterized to full fill the criteria of the good radiopharmaceutical. The physical and chemical characteristics of ¹⁷⁵Yb-EDTMP had been studied. It consists of: pH, solution clearity, the radiochemical purity that was determined by paper chromatography and paper electrophoresis techniques, electricity charge was determined by paper electrophoresis, stability, lipophilicity of ¹⁷⁵Yb-EDTMP was obtained by determination of octanol-water partition and the plasma binding protein was in-vitro investigated with precipitation method using 5% of trichloroacetic acid solution, and the binding to hydroxyapatite. From the experiment, it was obtained that the ¹⁷⁵Yb-EDTMP solution has the pH of 7, clear, the radiochemical purity of 98.66 ± 0.53%, and the negative electric charge. The compound of ¹⁷⁵Yb-EDTMP has lipophilicity (P) of 0.0135 ± 0.003%, the human plasma binding protein of 8.94 ± 0.66%, and the hydroxyapatite binding of 94.78 ± 2.16%. Stability evaluation indicated that ¹⁷⁵Yb-EDTMP solution was still stable for nine days at room temperature with the radiochemical purity more than 95% (98.62 ± 0.83%). This study expects that ¹⁷⁵Yb-EDTMP compound can fulfill the requirement as radiopharmaceutical for use in palliative treatment of painful bone metastases and supports the development of nuclear medicine in Indonesia. (author)