The biodistribution and tissue toxicity of intravenously administered 225-a
ctinium (Ac-225) complexed with acetate, ethylene diamine tetraacetic acid
(EDTA), 1, 4, 7, 10, 13-pentaazacyclopentadecane-N, N', N ", N''', N''''-pe
ntaacetic acid (PEPA), or the "a" isomer of cyclohexyl diethylenetriamine p
entaacetic acid (CHX-DTPA), were examined. The percent of injected dose per
organ and per gram of tissue for each chelate complex was determined. Ac-2
25-CHX-DTPA was evaluated further for radiotoxic effects. Mice receiving gr
eater than or equal to 185 kBq Ac-225-CHX-DTPA suffered 100% morbidity by 5
days and 100% mortality by 8 days postinjection, and all animals evaluated
had significant organ damage. The in vivo instability of the Ac-225-CHX-DT
PA complex likely allowed accumulation of free Ac-225 in organs, which resu
lted in tissue (C) 1999 Elsevier Science Inc. All rights reserved. patholog
y.