Description

Proviron 30 x 25mg

Like other AAS, mesterolone is an agonist of the androgen receptor (AR).^[2] Mesterolone is described as a very poor anabolic agent due to inactivation by 3α-hydroxysteroid dehydrogenase (3α-HSD) in skeletal muscle tissue, similarly to DHT and mestanolone (17α-methyl-DHT).^[2] In contrast, testosterone is a very poor substrate for 3α-HSD, and so is not similarly inactivated in skeletal muscle.^[2] Because of its lack of potentiation by 5α-reductase in “androgenic” tissues and its inactivation by 3α-HSD in skeletal muscle, mesterolone is relatively low in both its androgenic potency and its anabolic potency.^[2] However, it does still show a greater ratio of anabolic activity to androgenic activity relative to testosterone.^[2]

Mesterolone is not a substrate for 5α-reductase, as it is already 5α-reduced, and hence is not potentiated in so-called “androgenic” tissues such as the skin, hair follicles, and prostate gland.^[2]

Mesterolone is not a substrate for aromatase, and so cannot be converted into an estrogen.^[2] As such, it has no propensity for producing estrogenic side effects such as gynecomastia and fluid retention.^[2] It also has no progestogenic activity.^[2]

Because mesterolone is not 17α-alkylated, it has little or no potential for hepatotoxicity.^[2] However, its risk of deleterious effects on the cardiovascular system is comparable to that of several other oral AAS.^[2]