Estradiol/norethisterone
Estradiol/norethisterone ( E2/NET ) , tentative brand name Netagen or Netagen 403 , was a combination of estradiol ( E2 ) , an estrogen , and norethisterone ( NET ) , a progestin , which was studied as a birth control pill to prevent pregnancy in women . 
<triplet> Estradiol/norethisterone <subj> combination <obj> instance of