Masteron 100 is a modified form of Dihydrotestosterone, with a methyl group at the 2nd carbon (carbon alpha) atom. This modification is responsible for the anabolic strength increase. This methyl group makes it harder for the enzyme 3-hydroxysteroid dehydrogenase to metabolize Masteron. This enzyme is abundantly present in muscle tissue, and is responsible for degrading any DHT into two inactive metabolites: 3-Alpha Androstanediol and 3-Beta Androstanediol. Because of this enzyme DHT is not anabolic in muscle tissue at all. It is believed that if the enzyme 3-hydroxysteroid dehydrogenase was neutralized, DHT would actually be a very powerful anabolic steroid. Drostanolone’s methyl group addition makes it immune to this enzyme.
Masteron 100 as an Anti-Estrogen
Dromostanolone has some reputation for anti-estrogenic activity, but in actuality this effect is fairly subtle. If due to use of aromatizing steroids ( see other aromatizing steroids here ), a steroid cycle would produce substantially excessive levels of estrogen, adding Masteron to the cycle will not fix that. Instead, an anti-aromatase such as letrozole or anastrozole should be used. However, where only a moderate amount of aromatizing steroid is being used, Masteron 100 can in many instances be sufficient as the sole anti-estrogenic agent.