1,4,6-Androstatrien-3,17-dione

1,4,6-Androstatrien-3,17-dione (ATD) is a potent irreversible aromatase inhibitor that inhibits estrogen biosynthesis by permanently binding and inactivating aromatase in adipose and peripheral tissue. It is used to control estrogen synthesis.

ATD is present in some over-the-counter bodybuilding supplements such as Rebound XT, Novedex XT and Inhibit-E. While not banned, ADT may cause positive urinanalysis results leading to disqualification from competitive sports due to its similar properties to banned substances.

A related agent is exemestane (Aromasin).