Following a systematic search of desferrithiocin analogs, a polyether derivative, deferitazole (formerly
FBS0701), has entered into phase 1 and 2 clinical trials with promising biological properties. However, until
now, detailed physicochemical properties of this chelator have not been reported. The compound displays
a high affinity and selectivity for iron(III) as demonstrated by the log β2 = 33.39 ± 0.03 and the pFe3+ value of
22.3. Two equilibrating isomeric forms of the iron(III) complex exist under biological conditions. Deferitazole
also binds the trivalent metals AlIII and LaIII with high affinity; log β2 values, 26.68 and 21.55 respectively. The
affinity of deferitazole for divalent cations is somewhat lower, with the exception of CuII which possesses a
log β2 value of 25.5; deferitazole scavenges iron from labile sources such as citrate and albumin with
efficiencies comparable with those of other therapeutic iron chelators, including deferasirox, deferiprone
and desferrioxamine. The FeIII(deferitazole)2 is stable under physiological conditions and does not redox
cycle. The high affinity of deferitazole for iron(III) renders it unlikely that this chelator will lead to the redistribution
of iron and consequently deferitazole shows considerable promise as a therapeutic iron(III) chelator.