Gestrinone, also known as 17α-ethynyl-18-methyl-19-nor-δ 9,11 -testosterone, as well as 17α-ethynyl-18-methylestra-4,9,11-trien-17β-ol-3-one or as 13β-ethyl-18,19-dinor-17α-pregna-4,9,11-trien-20-yn-17β-ol-3-one, is a synthetic estrane steroid and a derivative of testosterone .   It is more specifically a derivative of norethisterone (17α-ethynyl-19-nortestosterone) and is a member of the gonane (18-methylestrane) subgroup of the 19-nortestosterone family of progestins.     Gestrinone is the C18 methyl derivative of norgestrienone (17α-ethynyl-19-nor-δ 9,11 -testosterone) and the δ 9,11 analogue of levonorgestrel (17α-ethynyl-18-methyl-19-nortestosterone) and is also known as ethylnorgestrienone due to the fact that it is the C13β ethyl variant of norgestrienone.   It is also the C17α ethynyl and C18 methyl derivative of the AAS trenbolone .  
Schering AG filed for a patent for NETA in June 1957, and the patent was issued in December 1960.  The drug was first marketed, by Parke-Davis as Norlestrin in the United States , in March 1964.   This was a combination formulation of mg NETA and 50 μg ethinylestradiol and was indicated as an oral contraceptive .   Other early brand names of NETA used in oral contraceptives included Minovlar and Anovlar .