Nandrolone decanoate

Dosages

A dosage of nandrolone decanoate of 25 to 50 mg once every 6 to 12 weeks (working out to an average exposure of about 2 to 8 mg per week) by intramuscular injection is considered to be appropriate for general androgen replacement therapy in women.^[32][33][20] A dosage of 50 mg once every 2 to 4 weeks by intramuscular injection is used in the prevention and treatment of postmenopausal osteoporosis and in the palliative treatment of inoperative breast cancer.^[2][6][34] For children aged 2 to 13 years, the average dosage for anemia of chronic kidney disease is 25 to 50 mg every 3 to 4 weeks by intramuscular injection.^[18] Dosages in men and for other uses have also been described.^{[18][19][6][2][4]}

Available forms

Nandrolone decanoate has been available in 25 mg/mL, 50 mg/mL, 100 mg/mL, and 200 mg/mL formulations in oil solution for intramuscular injection.^[21][4]

Virilization

Nandrolone decanoate causes virilization as a common side effect in women, including acne, hoarseness of the voice, hirsutism (excessive facial/body hair growth), and libido changes, among others.^[6] Clitoral enlargement is an uncommon symptom of virilization that can occur.^[6] Virilization is especially prevalent and marked at high dosages of nandrolone decanoate and/or with long-term treatment, and some aspects of virilization like voice deepening can be irreversible.^[6][19][4] Hoarseness is often the first sign of voice changes.^[6] Although said to be only slightly androgenic, nandrolone decanoate may still occasionally cause virilization at recommended dosages in women, especially with long-term treatment.^[4] A minor though statistically insignificant incidence of virilization has been observed in women treated with nandrolone decanoate short-term at a dosage of 100 mg every 2 weeks for 12 weeks.^[4] Conversely, long-term (>1 year) studies have shown significant virilization in women even at a dosage of 50 mg every 2 or 3 weeks.^[4]

Pharmacodynamics

Nandrolone decanoate is a nandrolone ester, or a prodrug of nandrolone.^{[6][39][4][13]} As such, it is an androgen and anabolic steroid, or an agonist of the AR, the biological target of androgens like testosterone and DHT.^{[6][4][13][39]} Relative to testosterone, nandrolone decanoate has enhanced anabolic effects and reduced androgenic effects.^[6][39][13] 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.^[4][13][28] 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.^[13] 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.^[4][27] For this reason, they are considered to be among the most appropriate AAS for use in women and children.^[4][14]

Androgenic effects like virilization are relatively uncommon with nandrolone decanoate at recommended dosages, though may still occur especially at higher dosages or with extended use.^[4][6] The low androgenicity of nandrolone decanoate 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.^[3][4][13] 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.^[4][27][28]

In addition to its anabolic and androgenic activity, nandrolone decanoate has low estrogenic activity (via its metabolite estradiol) and moderate progestogenic activity.^[4] This may result in side effects such as fluid retention and gynecomastia.^[4] Like other AAS, nandrolone decanoate has antigonadotropic effects.^[4] 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.^[4] Both the androgenic activity and the progestogenic activity of nandrolone decanoate may contribute to its antigonadotropic potency.^[4] Relative to testosterone, due to its lower estrogenic potency, much less of the antigonadotropic potency of nandrolone decanoate is derived from its estrogenic activity.^[4]

Pharmacokinetics

Upon intramuscular injection in oil, which results in the formation of a long-lasting depot in the muscle, nandrolone decanoate is stored unchanged and is slowly absorbed into the body.^[3] Once in the circulation, it is converted into nandrolone, which is the active form of the drug.^[2] There is a sharp spike in nandrolone levels 24 to 48 hours after an intramuscular injection of nandrolone decanoate, followed by a steady decline to baseline levels within approximately two or three weeks.^[4][6] The bioavailability of nandrolone decanoate 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.^[1] Like testosterone, nandrolone is highly protein-bound and is present in the blood in both bound and free fractions.^[3] It has very low affinity for sex hormone-binding globulin (SHBG), about 5% of that of testosterone and 1% of that of DHT.^[3][40]

Nandrolone decanoate is rapidly hydrolyzed in the blood by esterases into nandrolone, with a terminal half-life of one hour or less.^[3][2] It does not appear to be hydrolyzed in muscle or fat.^[41] 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.^[3] The metabolites of nandrolone include 5α-dihydronandrolone, 19-norandrosterone, and 19-noretiocholanolone, with 19-norandrosterone being the major metabolite.^[3] Other metabolites include 19-norandrostenedione, 19-norandrostanediols, 19-norepiandrosterone, and conjugates.^[3] 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.^{[4][17][3][42]}

The elimination half-life of nandrolone decanoate administered by intramuscular injection is approximately 6 to 12 days.^[2][4] Studies that have assessed the duration of nandrolone decanoate 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.^[43][44] The blood half-life for the combined process of hydrolysis into nandrolone and elimination of nandrolone is 4.3 hours.^[2] Nandrolone and its metabolites are excreted in the urine, mainly in the form of conjugates.^[3]

Although nandrolone decanoate is usually administered by intramuscular injection, it has been found to be similarly effective when administered by subcutaneous injection.^[45] The pharmacokinetics of nandrolone decanoate via subcutaneous injection closely resemble those of intramuscular injection.^[45] However, subcutaneous injection is considered to be easier, more convenient, and less painful compared to intramuscular injection.^[45] In addition, research suggests that most intramuscular injections in practice are in fact subcutaneous injections.^[45]

Generic names

Nandrolone decanoate is the generic name of the drug and its USANTooltip United States Adopted Name and BANTooltip British Approved Name.^{[8][9][10][11]} It has also been referred to as nandrolone decylate.^{[8][9][10][11]}

Brand names

Nandrolone decanoate is or has been marketed under the brand names Deca-Durabolin, Deca-Durabol, Decaneurabol, Metadec, and Retabolil, among others.^{[8][9][10][11]}

Availability

Nandrolone decanoate is available widely throughout the world, including in the United Kingdom, other European countries, Australia, New Zealand, Latin America, Asia, and elsewhere in the world.^{[9][11][4][16]} Nandrolone commercial brand name products have been discontinued in United States and Canada.^[52][53] However, it is still available via some compounding pharmacies in the United States. Its availability is becoming increasingly limited with time.^[4]

Legal status

Nandrolone decanoate, along with other AAS, is a schedule III controlled substance in the United States under the Controlled Substances Act.^[54]