MasteronDrostanolone Propionate & Enanthate — Research Reference by QSC Peptides

Masteron (Drostanolone) is 2α-methyl-dihydrotestosterone (2α-methyl-DHT) — a DHT derivative with a 2-methyl group that prevents both aromatization and further 5α-reduction, but uniquely confers anti-estrogenic properties through direct CYP19A1 (aromatase) inhibition.

The aromatase inhibitor (AI) activity of drostanolone makes it pharmacologically distinct from all other DHT derivatives. It competes with androgen substrates at the aromatase active site, reducing estrogen biosynthesis — a property generally absent in pure AR agonists like testosterone or nandrolone. This makes Masteron uniquely valuable in research studying the interaction between androgen administration and estrogen biosynthesis inhibition.

AR Pharmacology — Low Ratio, Tissue Significance

Despite the modest 62:25 anabolic:androgenic ratio, drostanolone has documented significant AR activity in androgenic tissues. The low in vitro ratio reflects test conditions; in vivo it competes effectively with testosterone for AR binding due to 5α-reduced state (higher AR affinity than testosterone).