The effect of formulation conditions on the distribution of sup(99m)Tc(NaBH4)-HEDP components separated by anion exchange HPLC

Reduction of sup(99m)TcO4- by NaBH4 in the presence of HEDP leads to a mixture of sup(99m)Tc-containing complexes which can be separated by anion exchange high performance liquid chromatography (HPLC). The distribution of complexes within this mixture can be varied by controlling pH, the concentration of HEDP, the concentration of technetium, and the presence of air. Suitable control of these formulation conditions can yield mixtures which consist of essentially (>85%) one component. Arguments are presented to support the view that the components of sup(99m)Tc(NaBH4)-HEDP and sup(99m)Tc(NaBH4)-MDP mixtures are in fact oligomeric or polymeric complexes that can contain technetium centers in at least two different oxidation states. (author)