Biodistribution studies of the Re-186 complex of 3-amino-1-hydroxypropylidene-1,1-bisphosphonic acid in mice

Preliminary studies of Re-186-labelled 3-amino-1-hydroxypropylidene-1,1-bis phosphonic acid (APD) were performed to determine its potential for bone pa in palliation, and as a treatment for increased bone resorption. The synthe sis of Re-186-APD was carried out by reduction of Re-186-perrhenate in the presence of SnCl2. The APD kit, comprising 2.5 mg of APD, 2.5 mg of gentisi c acid and 1 mg of Sn++ as SnCl2 2H(2)O, was prepared in-house. The APD was labelled with Re-186 and injected intravenously into normal mice. Mice wer e subsequently sacrificed at 1, 3, 24, 48, 72, 168 and 240 h post-injection . The greatest accumulation of Re-186-labelled APD was found in bone, resul ting in bone-to-blood ratios of 25, 35, 65, 100, 151, 181 and 189, respecti vely. Re-186-APD showed high uptake in bone, and relatively low uptake in s oft tissue, suggesting that Re-186-APD is a potential agent for bone therap y. ((C) 1999 Lippincott Williams & Wilkins).