Evaluation of the biological and scanning distribution of hydroxyapatite-153Sm radiotherapeutic agent

Fixation of 153Sm labeled hydroxyapatite (HA) in the synovial capsule and extra articular localization were evaluated by means of biological distribution tests and gamma scanning studies. These were carried out using HA-153Sm with particle size ranging between 5 and μm, and radiochemical purity above 99%. Animal models used were wistar rats and new zealand rabbits. Rabbits were injected with 7,4 MBq of HA-153Sm while rats received between 1,85 and 92,6 MBq of HA-153Sm. In both cases injection was given in the intra articular area. After injection, scanning images were obtained in rabbits on the 1st, 3rd and 7st day and in rats on the 2nd and 7th day. Biological distribution studies are conducted in the 2 hours to 9 days range in rats and one the 7th day in rabbits. No extra articular localization of HA-153Sm was found in scanning conducted on rabbits by the 1st, 3rd and 7st day after injection, neither on rats by the 2nd and 7th day. Biological distributions for rabbits and rats show localization above 99% in the intra articular area, during the evaluated periods of time. The evaluations of the biological distribution and the scintigraphic images show that fixation of HA-153Sm in the synovial capsule up to the 9th day is very high