Pharmacodynamics As an AAS,<unk>  is an agonist of the androgen receptor (AR), similarly to androgens like testosterone and dihydrotestosterone (DHT). It is a substrate for 5α-reductase like testosterone, and so is potentiated analogously in so-called "androgenic" tissues like the skin, hair follicles, and prostate gland via transformation into the more potent AR agonist mestanolone (17α-methyl-DHT). As such,<unk>  has a relatively low ratio of anabolic to androgenic activity, with a similar ratio to that of testosterone (close to 1:1), and this makes it among the most androgenic AAS. Due to efficient aromatization into the potent and<unk> abolism-resistant estrogen<unk> hylestradiol (17α-methylestradiol),<unk>  has relatively high estrogenicity and hence potential for estrogenic side effects such as gynecomastia and fluid retention. The drug possesses negligible progestogenic activity. Due to its combined disadvantages of a relatively poor ratio of anabolic to androgenic activity, unusually high estrogenicity, and the potential for hepatotoxicity (as with other 17α-alkylated AAS),<unk>  has not been used as commonly as many other AAS either in medicine or for physique- or performance-enhancing purposes. Pharmacokinetics Absorption<unk>  has dramatically improved oral bioavailability and<unk> abolic stability relative to testosterone. This difference is due to the C17α<unk> hyl group, which results in steric hindrance and prevents<unk> abolism. The oral bioavailability of<unk>  is about 70%, and it is well-absorbed from the gastrointestinal tract.<unk>  can also be taken buccally or sublingually. Although effective orally,<unk>  is more effective by these non-oral routes, which are said to approximately double its bioavailability and require half the oral dosage. Circulating levels of<unk>  with administration of 1.25 to 2.5 mg/day oral<unk>  in women are in the range of 20 to 30 ng/dL. For comparison to testosterone,<unk>  is at least as potent as an AAS. However, due to the large decrease in sex hormone-binding globulin (SHBG) levels and hence increase in free unbound testosterone caused by<unk> , androgenic effects may be greater than reflected merely by<unk>  levels. Distribution<unk>  is highly protein-bound, by approximately 98%. The medication has low but significant affinity for human serum sex hormone-binding globulin (SHBG), about 25% of that of testosterone and 5% of that of DHT.<unk> abolism The biological half-life of<unk>  is approximately 3 hours (range 2.5–3.5 hours). The duration of action of<unk>  is said to be 1 to 3 days, and is described as relatively short among AAS. Excretion<unk>  is excreted 90% in the urine as conjugates and other<unk> abolites, and 6% in feces.
Methyltestosterone
Allyltestosterone
Dihydrotestosterone
Luteinizing hormone
Androgen
Methylestradiol
Methyl-1-testosterone
Progestogen 