 Gestrinone, the 18-methyl analogue of norgestrienone, has even greater androgenic activity than norgestrienone, as this modification increases androgenic activity similarly.The metabolism of norgestrienone in humans has been studied.Norgestrienone, also known as 17α-ethynyl-19-nor-δ9,11-testosterone or as 17α-ethynylestra-4,9,11-trien-17β-ol-3-one, as well as δ9,11-norethisterone or 17α-ethynyltrienolone (17α-ethynyltrenbolone), is a synthetic estrane steroid and a derivative of testosterone and 19-nortestosterone.