Maintaining radiochemical purity of [¹⁷⁷Lu]Lu-DOTA-PSMA-617 for PRRT by reducing radiolysis

[¹⁷⁷Lu]Lu-DOTA-PSMA-617 for PRRT is subject to radiolysis and therefore loses receptor affinity. This will be detrimental for treatment efficacy. In this study optimal quencher(s) (combinations) are determined to maintain radiochemical purity with a downscaled model. Downscaled model in terms of activity, but at similar concentrations. DOTA-PSMA-617 was labeled with [¹⁷⁷Lu]LuCl₃ with different molar- and volume activities. Either methionine, ethanol or both showed superior effects on the stabilizing radiochemical purity of [¹⁷⁷Lu]Lu-DOTA-PSMA-617. As a consequence, radiochemical purity of [¹⁷⁷Lu]Lu-DOTA-PSMA-617 could be maintained by the addition of methionine and/or ethanol and downscaled model was proven and complementary. (author)