(3S,4aS,5aR,6aS,6bS,9aS,11aS,11bR)-9a,11b-dimethyl-9-(pyridin-3-yl)-1,2,3,4,5a,6,6a,6b,7,9a,10,11,11a,11b-tetradecahydrocyclopenta[1,2] phenanthro[8a,9-b]oxiren-3-yl acetate is an impurity of Abiraterone acetate. Abiraterone acetate is a CYP17A1 inhibitor and by extension androgen synthesis inhibitor.