ABSTRACT
Mifepristone, initially known with the name of RU486, is 17b-hydroxy-11b-(4-dimethylaminophenyl-1)-17a-(prop-1-ynyl)-estra-4,9-diene-3-one. It is a derivative of noethindrone, but it differs from norethindrone in the presence of a 4-dimethylaminophenyl group at the 11b position and a 1-propynyl chain at the 17aposition. It is a progesterone antagonist at the receptor level. It binds to the progesterone receptor, with the same affinity as progesterone itself. It also binds to the glucocorticoid receptor but it does not bind to mineralocorticoid or oestrogen receptors.
