Newly discovered orally active pure antiestrogens

Abstract In order to develop orally active pure antiestrogens, we incorporated the carboxy-containing side chains into the 7α-position of the steroid scaffold and found that 17-keto derivative CH4893237 ( 12b ) functioned as a pure antiestrogen with its oral activity much superior to clinically used pure antiestrogen, ICI182,780. Results from the pharmacokinetic evaluation indicated that the potent antiestrogen activity at oral dosing in mice attributed to both improved absorption from the intestinal wall and metabolic stability in liver.