Formulation and evaluation of an in-house freeze-dried EDTMP kit for the simple preparation of 153Sm-based bone seeking agent EDTMP radiopharmaceuticals.

Bone metastases are a common condition occurred at the end stage of prostate and breast cancer patients. Bonepain palliation radiopharmaceutical based on ethylenediamine tetra(methylene phosphonic acid) (EDTMP) ligand has been proven to effectively treat bone metastases and improve patients' quality of life. In this report, the formulation of freeze-dried EDTMP kits for the convenient preparation of 153Sm-EDTMP and the subsequent quality control were described. Lyophilized EDTMP kits were produced employing EDTMP, NaOH, and CaCO3. Important parameters of freeze-dried EDTMP kits such as pH, sterility, and pyrogenicity were investigated. The 153Sm-EDTMP was prepared via a complexation reaction between 153SmCl3 solution (∼65 mCi) and thawed EDTMP kit. The reaction mixture was then incubated at room temperature at different time points. The radiochemical purities of resultant 153Sm-EDTMP were analyzed by the radio-TLC method using Whatman paper No. 1 as stationary phase and a mixture of ammonium hydroxide 25%:water (9:1, v/v) as an eluting solvent. One batch of freeze-dried EDTMP kits with 97 kit vials was successfully produced. Each kit vial is composed of 36 mg EDTMP, 14.5 mg NaOH, and 7.4 mg CaCO3. The 153Sm-EDTMP complex was obtained with high radiochemical purity (≥99%) and stability for up to 8 days. The evaluation of pH, sterility, and pyrogenicity of prepared EDTMP kits revealed a pH of 7, sterile, and pyrogen-free. In conclusion, the freeze-dried EDTMP kit can be used for the simple preparation of 153Sm-EDTMP. However, further investigations to validate the kit formulation process are required. [ABSTRACT FROM AUTHOR]