the affinities of steroids for the e2 receptor were as follows : ethynodiol diacetate ( ki of 1.3 x 10 ( -7 ) m ) greater than 17alpha-ethynyl-estra-4-ene-3beta , 17beta-diol greater than norethindrone acetate greater than norethindrone greater than 5alpha-dihydronorethindrone greater than lynestrenol ( ki of 8.4 x 10 ( -7 ) m ) .
C0068980
norethindrone acetate
C0028356
norethindrone