Comparison of the distribution of radioiodinated di- and tri-hydroxyphenylethylene estrogens in the immature female rat

The uptake, retention and tissue to blood ratios of two non-steroidal, 125I-labeled iodoestrogens, an iodotrihydroxyphenylethylene, 2-iodo-1,2-bis(4-hydroxyphenyl)-2-(3-hydroxyphenyl)ethylene and an iododihydroxyphenylethylene, 2-iodo-1,1-bis(4-hydroxyphenyl)-2-phenylethylene, were compared after intraperitoneal injection in immature female rats. The iodotrihydroxyphenylethylene showed an unexpectedly prolonged specific retention in estrogen target tissue, lasting up to 72 h. It was rapidly cleared from blood and non-target tissues so that uterus or ovary to blood ratios of greater than 100 were seen at 2 and 3 days. This iodotrihydroxyphenylethylene may have clinical potential for estrogen receptor-containing cancers.