Use
norethindrone, the discovery of the potentprogestin activity of 17α-ethinyltestosterone (ethisterone) and19-norprogesterone preceded the development of these potentprogestins. both are orally active, with the 17α-ethinyl groupblocking oxidation to the less active 17-one. the rich electrondensity of the ethinyl group and the absence of the 19-methylgroup greatly enhance progestin activity. both compoundswere of great importance as progestin components of oralcontraceptives, although currently, use of norethynodrel isminimal. norethindrone, usp, and norethindrone acetate,usp, are widely used for all the usual indications of the progestins,as well as being components of oral contraceptives.because these compounds retain key features of the testosteronestructure, including the 17β-oh, it is not surprisingthat they possess some androgenic side effects.