<unk> , formerly sold under the brand name Lentaron among others, is a steroidal, selective aromatase inhibitor which is used in the treatment of estrogen receptor-positive breast cancer in postmenopausal women. The drug is not active orally, and was available only as an intramuscular depot injection.<unk>  was not approved by the United States FDA and the injectable form that was used in Europe in the past has been withdrawn from the market.<unk>  is an analogue of androstenedione.<unk>  is often used to suppress the production of estrogens from anabolic steroids or prohormones. It also acts as a prohormone to 4-hydroxytestosterone, an active steroid which displays weak androgenic activity in addition to acting as a weak aromatase inhibitor.
Formestane
Gestodene
Hexestrol
Benzestrol
Fosfestrol
Moxestrol
Mestanolone
Dienestrol