Drostanolone propionate, which also may be called Masteril™ or Masteron ™, is an anabolic steroid, a drug that mimics the effects of naturally occurring testosterone in the body. Drostanolone propionate has been used as a hormone therapy in conjunction with other treatments for breast cancer, but unpleasant side effects keep it from being widely used for this purpose. Another effect of this drug is to increase muscle mass , which has led to its often unapproved and controversial use by athletes and bodybuilders who want to increase strength or a muscular appearance. Anabolic steroids may also be used in the treatment of HIV /AIDS or wasting diseases, to help maintain body mass and strength.
Drostanolone propionate is a prodrug of drostanolone .  Like other AAS, drostanolone is an agonist of the androgen receptor (AR).  It is not a substrate for 5α-reductase and is a poor substrate for 3α-hydroxysteroid dehydrogenase (3α-HSD), and therefore shows a high ratio of anabolic to androgenic activity.  As a DHT derivative, drostanolone is not a substrate for aromatase and hence cannot be aromatized into estrogenic metabolites .  While no data are available on the progestogenic activity of drostanolone, it is thought to have low or no such activity similarly to other DHT derivatives.  Since the drug is not 17α-alkylated , it is not known to cause hepatotoxicity .