Preparation, stability studies and pharmacological behavior of [Re-186]Re-HEDP

Tc-99m-HEDP is widely used as a bone imaging agent and its Re analog [Re-18 6]Re-HEDP is now well established as a therapeutic radiopharmaceutical for palliation of pain due to bone metastases. In the present paper, we report the work carried out for the preparation of stable Re-186-HEDP which retain s RC purity up to 5 days when stored at 4 degrees C. Re-186 was prepared by irradiation of natural Re metal at a flux of 3 x 10(13) neutrons/cm(2)/s f or seven days and processed after a cooling period of four days. The specif ic activity of Re-186 formed was similar to 35 mCi/mg. A complex with RC pu rity >98% could be prepared by varying the reaction conditions. By carefull y optimizing the reaction and storage conditions, a complex which was stabl e for over 3 days could be synthesized. Bio-distribution studies carried ou t in rats revealed similar to 30% bone uptake of Re-186-HEDP at 3 h postinj ection which remained almost constant for 48 h, at which time there was neg ligible activity in other organs. (C) 1999 Elsevier Science Ltd. All rights reserved.