Pharmacodynamics Nandrolone, the active form of<unk> .<unk>  is a nandrolone ester, or a prodrug of nandrolone. As such, it is an androgen and anabolic steroid, or an agonist of the AR, the biological target of androgens like testosterone and DHT. Relative to testosterone,<unk>  has enhanced anabolic effects and reduced androgenic effects. It is considered to have strong anabolic effects but weak androgenic effects, with respective potency ratios of 3.29–4.92 and 0.31–0.41 (index value 10.6–12.1 or about an 11:1 ratio of myotrophic to androgenic effect) relative to testosterone propionate. This is defined specifically on the basis of a rodent model in which change in the weights of the rat bulbocavernosus/levator ani muscle ("anabolic" or "myotrophic" activity) and the rat ventral prostate or seminal vesicles ("androgenic" activity) are compared with testosterone and then used to form a ratio. Along with oxandrolone (which has a ratio of about 10:1), nandrolone esters are thought to have the highest ratio of anabolic to androgenic effect of any other AAS. For this reason, they are considered to be among the most appropriate AAS for use in women and children. Androgenic effects like virilization are relatively uncommon with<unk>  at recommended dosages, though may still occur especially at higher dosages or with extended use. The low androgenicity of<unk>  is thought to be due to the fact that whereas many other AAS like testosterone are potentiated via transformation by 5α-reductase into more potent AR agonists like DHT in specific tissues including the skin, hair follicles, prostate gland, liver, and brain, nandrolone is instead inactivated by 5α-reductase via transformation into the low-affinity AR ligand 5α-dihydronandrolone in such tissues. This is thought to result in a much lower incidence and magnitude of facial/body hair growth, scalp hair loss, and possibly prostate issues like prostate enlargement and prostate cancer with nandrolone esters relative to testosterone. In addition to its anabolic and androgenic activity,<unk>  has low estrogenic activity (via its metabolite estradiol) and moderate progestogenic activity. This may result in side effects such as fluid retention and gynecomastia. Like other AAS,<unk>  has antigonadotropic effects. It has been found to suppress testosterone levels by 57% at a dosage of 100 mg/week and by 70% at a dosage of 300 mg/week in men following 6 weeks of treatment. Both the androgenic activity and the progestogenic activity of<unk>  may contribute to its antigonadotropic potency. Relative to testosterone, due to its lower estrogenic potency, much less of the antigonadotropic potency of<unk>  is derived from its estrogenic activity. Pharmacokinetics Upon intramuscular injection in oil, which results in the formation of a long-lasting depot in the muscle,<unk>  is stored unchanged and is slowly absorbed into the body. Once in the circulation, it is converted into nandrolone, which is the active form of the drug. There is a sharp spike in nandrolone levels 24 to 48 hours after an intramuscular injection of<unk> , followed by a steady decline to baseline levels within approximately two or three weeks. The bioavailability of<unk>  is 53 to 73% with intramuscular injection and varies with the site of injection, with the highest bioavailability seen when injected into the gluteal muscle. Like testosterone, nandrolone is highly protein-bound and is present in the blood in both bound and free fractions. It has very low affinity for sex hormone-binding globulin (SHBG), about 5% of that of testosterone and 1% of that of DHT.<unk>  is rapidly hydrolyzed in the blood by esterases into nandrolone, with a terminal half-life of one hour or less. It does not appear to be hydrolyzed in muscle or fat. The metabolism of nandrolone occurs in the liver and is very similar to that of testosterone, including reduction by 5α-reductase and 5β-reductase, dehydrogenation by 3α-hydroxysteroid dehydrogenase, 3β-hydroxysteroid dehydrogenase, and 17β-hydroxysteroid dehydrogenase, and conjugation. The metabolites of nandrolone include 5α-dihydronandrolone, 19-norandrosterone, and 19-noretiocholanolone, with 19-norandrosterone being the major metabolite. Other metabolites include 19-norandrostenedione, 19-norandrostanediols, 19-norepiandrosterone, and conjugates. Nandrolone also undergoes aromatization into estradiol similarly to testosterone, though at a rate of only about 20% of that of testosterone or possibly even less; one study found virtually no aromatization of nandrolone in men. The elimination half-life of<unk>  administered by intramuscular injection is approximately 6 to 12 days. Studies that have assessed the duration of<unk>  via its anabolic effects, for instance on nitrogen balance, have found that a single 50 to 100 mg intramuscular injection had a duration of about 18 to 25 days. The blood half-life for the combined process of hydrolysis into nandrolone and elimination of nandrolone is 4.3 hours. Nandrolone and its metabolites are excreted in the urine, mainly in the form of conjugates. Although<unk>  is usually administered by intramuscular injection, it has been found to be similarly effective when administered by subcutaneous injection. The pharmacokinetics of<unk>  via subcutaneous injection closely resemble those of intramuscular injection. However, subcutaneous injection is considered to be easier, more convenient, and less painful compared to intramuscular injection. In addition, research suggests that most intramuscular injections in practice are in fact subcutaneous injections.
Nandrolone decanoate
Nandrolone hydrogen succinate
Androstanolone benzoate
Nandrolone propionate
Androstanolone propionate
Cloxotestosterone acetate
Nandrolone cypionate
Nandrolone caproate