Development of an in vivo radionuclide generator by labeling bleomycin with 191Os

Bleomycin (BLM) has been labeled with various radioisotopes and widely used in therapy and diagnosis. ¹⁹¹Os is a parent radionuclide with 15.4 day half-life and decays by beta emission to ^191mIr, which is a radionuclide with 4.96 s half-life. BLM was labeled with ¹⁹¹Os-hexachloro-osmate and its distribution and stability in wild-type mice was determined. The complex was obtained at the pH 2 in normal saline at 90 °C in 48 h. Radio-TLC showed an overall radiochemical yield of 93–97%, radio-chemical purity > 97%. The biodistribution study for ¹⁹¹Os-hexachloro-osmate and ¹⁹¹Os-BLM were carried in wild type-mice up to 14 days. Lungs, liver and spleen uptake increased 24–72 h after administration of ¹⁹¹Os-BLM. 24 h after administration, the radioactivity of the kidney increased and remained constant.