radiosynthesis of 191os-2-acetylpyridine thiosemicarbazone complex, as an in vivo therapeutic radionuclide generator

introduction: due to the anti-proliferative properties of platinum group-thiosemicarbazone complexes, the production of 191os-labeled 2-acetyl pyridine 4-n-methylthiosemicarbazone (191os-apmts) was investigated. methods: [191osmium (t½= 15.4d) was produced via the 190os(n,γ)191os nuclear reaction using enriched target irradiated with thermal neutrons. reaction of in-house synthesized 2-acetylpyridine thiosemicarbazone (apmts) with 191os yielded [191os]apmts checked by itlc followed by stability, partition co-efficient and biodistribution determination. results: following synthesis and spectroscopic determination of the ligand (>99% chemical purity), the complex was prepared with a radiochemical purity of more than 95% (rtlc) and specific activity of 21.5 gb/mm and was stable in the formulation and presence of human serum at 37°c for up to 48h. the partition coefficient was determined (log p. 1.23). the biodistribution study up to 4 days demonstrated significant tissue uptake differences in the bone, blood, heart and thyroid. conclusion: this is the first os-191 labeled thiosemicarbazone designed as an in-vivo therapeutic radionuclide generator. further investigation is ongoing on the evaluation of the complex in tumor bearing animals.