Production, quality control and biodistribution studies of thulium-170-labeled ethylenediamine (tetramethylene phosphonic acid)

Abstract

Abstract Thulium-170 ( T 1/2 = 128.4 d, E β (max) = 968 keV, E γ = 84 keV (3.26%)) has radionuclidic properties suitable to be used in palliative therapy of bone metastases as an alternative to 89 SrCl 2 . 170 Tm can be produced by a relatively easy route involving thermal neutron bombardment on natural Tm 2 O 3 (100% 169 Tm) in medium flux research reactors. The requirement for an enriched target does not arise and radionuclidic impurities are not formed by radiative capture during neutron activation. In this study 170 Tm was produced using Tm(NO 3 ) 3 , prepared by neutron activation (3–4E13) of a natural sample. Ethylenediamine (tetramethylene phosphonic acid) (EDTMP) was synthesized and radiolabeled with 170 Tm. Complexation parameters were optimized to achieve maximum yields (>99%). The radiochemical purity of 170 Tm-EDTMP was checked by RTLC. It was found to retain its stability at room temperature even after 2 months of preparation (> 95%). Biodistribution studies of the complexes carried out in wild-type rats showed significant bone uptake with rapid clearance from blood. The properties of produced 170 Tm-EDTMP suggest applying a new efficient bone pain palliative therapeutic agent in the country instead of some other in-use radiopharmaceuticals, such as 89 SrCl 2 and 32 P, in order to overcome metastatic bone pains.