19-Norpregn-4-en-20-yn-3-one, 17-(acetyloxy)- 19-Norpregn-4-en-20-yn-3-one, 17-hydroxy-, acetate 19-Norpregnan-4-en-20-yn-3-one, 17-hydroxy-, acetate 38673-38-0 Norethindrone acetate