 Etynodiol diacetate is used in combination with an estrogen such as ethinylestradiol or mestranol in combined oral contraceptives for women.Etynodiol diacetate is virtually inactive in terms of affinity for the progesterone and androgen receptors and acts as a rapidly converted prodrug of norethisterone, with etynodiol occurring as an intermediate.Upon oral administration and during first-pass metabolism in the liver, etynodiol diacetate is rapidly converted by esterases into etynodiol, which is followed by oxygenation of the C3 hydroxyl group to produce norethisterone.