Synonyms: 4-hydroxy-androst-4-ene-17-dione;4-hydroxy-delta(sub4)-androstenedione;4-HYDROXYANDROST-4-ENE-3,17-DIONE;4-HYDROXYANDROSTENEDIONE;4-HYDROXY-4-ANDROSTENE-3,17-DIONE;4-ANDROSTEN-4-OL-3,17-DIONE;4-OHA;CGP-32349 
CAS: 566-48-3 
MF: C19H26O3 
MW: 302.41 
Chemical Properties Needles 
Usage An antitumor drug. An aromatase inhibitor 
Usage antineoplastic, aromatase inhibitor 


Lentaron Description

Formestanes (lentaron) is a type I steroidal aromatase inhibitor. Formestanes was developed for use in treatment of estrogen-receptor-positive breast cancer in post-menopausal women. 

For medical purposes, Formestanes (lentaron) is made in intramuscular depot form and injected. Formestanes is not used in oral form due to poor bioavailability, which makes the oral version inferior to aromasin, letrozole, and arimidex. 


Formestanes (lentaron) has been targeted specifically for the treatment of postmenopausal women. Unlike premenopausal women who produce most estrogen in the ovaries, postmenopausal women produce most estrogen in peripheral tissues with the help of the aromatase enzyme. 

Formestane, an aromatase inhibitor, can thus help to decrease the local production of estrogen by blocking the aromatase enzyme in peripheral tissues (ie. Adispose tissue of the breast) to treat hormone sensitive breast cancer.