2,5-Diamino-5,5-diphosphonovaleric Acid as a Ligand for an Osteotropic [sup.188]Re Radiopharmaceutical

A modified method for the preparation of 2,5-diamino-5,5diphosphonovaleric acid (DADP5) has been developed in the search for new synthetically available organic ligands to produce [sup.188]Re radiopharmaceuticals with an increased accumulation in the bone tissue. Interaction of the obtained acid with [sup.188]Re was studied by radio-TLC. An optimal system for separating unbound [sup.188]Re and labeled complex in a yield of at least 95% was found. The biological distribution of [sup.188]Re-DADP5 was studied based on direct radiometric data. The osteotropicity of [sup.188]Re-DADP5 and its increased accumulation in bone fracture sites, which represent oncological pathology models, was detected at a level comparable to known radiopharmaceuticals. Keywords: osteotropic radiopharmaceuticals, rhenium-188, 2,5-diamino-5,5diphosphonovaleric acid, biological distribution