Preparation and evaluation of 17 alpha-[125I]iodovinyl-11 beta-methoxyestradiol as a highly selective radioligand for tissues containing estrogen receptors: concise communication.

The moxestrol analog 17 alpha-[125I]iodovinyl-11 beta-methoxyestradiol was prepared in 95% radiochemical yield from the corresponding 17 alpha-(tributylstannyl) vinyl compound and no-carrier-added sodium [125I]iodide. The new radioligand was evaluated in immature female rats to determine the uptake in and selectivity for tissues containing estrogen receptors. At 1, 2, and 6 hr after injection, the agent demonstrates both high selectivity (uterus to blood ratio) and a high concentration in the target tissue. These values are considerably better than those previously reported for IVE2 or for the 16 alpha-radiohalogenated estradiols. The compound's biologic properties and its ease of preparation suggest that it would be a likely candidate for clinical use as an estrogen-receptor-seeking radiopharmaceutical.