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 . 
This is the most powerful of cycles designed to harden the physique for a pre-contest or cutting phase while also lending enough anabolic strength to facilitate lean mass addition or even a full-out bulk. All has remained the same as the intermediate Masteron cycle listed above with the exception of the addition of Trenbolone. It has long since been considered that the combination of Testosterone, Trenbolone, and Masteron is a stack that will provide some of the most notable and dramatic physique changes (provided that the user’s nutrition and training is adjusted to favor such outcomes). Trenbolone itself is extremely powerful and cannot convert into Estrogen. In combination with Masteron in such a cycle, and provided nutrition and training are impeccable, the majority of individuals should be able to achieve a competition-worthy physique.