Nandrolone, also known as 19-nortestosterone, is an androgen and anabolic steroid (AAS) which is used in the form of esters such as nandrolone decanoate (brand name Deca-Durabolin) and nandrolone phenylpropionate (brand name Durabolin). Nandrolone esters are used in the treatment of anemias, wasting syndromes, osteoporosis, breast cancer, and for other indications. They are not active by mouth and must be given by injection into muscle.
Side effects of nandrolone esters include symptoms of masculinization like acne, increased hair growth, voice changes, and increased sexual desire. They are synthetic androgens and anabolic steroids and hence are agonists of the androgen receptor (AR), the biological target of androgens like testosterone and dihydrotestosterone (DHT).Nandrolone esters have strong anabolic effects and weak androgenic effects, which give them a mild side effect profile and make them especially suitable for use in women. They are long-lasting prodrugs of nandrolone in the body.
Nandrolone esters were first described and introduced for medical use in the late 1950s. They are among the most widely used AAS worldwide. In addition to their medical use, nandrolone esters are used to improve physique and performance, and are said to be the most widely used AAS for such purposes. The drugs are controlled substancesin many countries and so non-medical use is generally illicit.
Nandrolone is an agonist of the AR, the biological target of androgens like testosterone and DHT. Unlike testosterone and certain other AAS, nandrolone is not potentiated in androgenic tissues like the scalp, skin, and prostate, hence deleterious effects in these tissues are lessened. This is because nandrolone is metabolized by 5α-reductase to the much weaker AR ligand 5α-dihydronandrolone (DHN), which has both reduced affinity for the androgen receptor (AR) relative to nandrolone in vitro and weaker AR agonistic potencyin vivo. The lack of alkylation on the 17α-carbon drastically reduces the hepatotoxic potential of nandrolone. Estrogen effects resulting from reaction with aromatase are also reduced due to lessened enzyme interaction, but effects such as gynecomastia and reduced libido may still occur at sufficiently high doses.
In addition to its AR agonistic activity, unlike many other AAS, nandrolone is also a potent progestogen. It binds to the progesterone receptor with approximately 22% of the affinity of progesterone. The progestogenic activity of nandrolone serves to augment its antigonadotropic effects, as antigonadotropic action is a known property of progestogens.
Anabolic and androgenic activity
Nandrolone has a very high ratio of anabolic to androgenic activity. In fact, nandrolone-like AAS like nandrolone itself and trenbolone are said to have among the highest ratio of anabolic to androgenic effect of all AAS. This is attributed to the fact that whereas testosterone is potentiated via conversion into dihydrotestosterone(DHT) in androgenic tissues, the opposite is true with nandrolone and similar AAS (i.e., other 19-nortestosterone derivatives). As such, nandrolone-like AAS, namely nandrolone esters, are the most frequently used AAS in clinical settings in which anabolic effects are desired; for instance, in the treatment of AIDS-associated cachexia, severe burns, and chronic obstructive pulmonary disease. However, AAS with a very high ratio of anabolic to androgenic action like nandrolone still have significant androgenic effects and can produce symptoms of masculinization like hirsutism and voice deepening in women and children with extended use.
Nandrolone has very low affinity for human serum sex hormone-binding globulin (SHBG), about 5% of that of testosterone and 1% of that of DHT. It is metabolizedby the enzyme 5α-reductase, among others. Metabolites of nandrolone include 5α-dihydronandrolone, 19-norandrosterone, and 19-noretiocholanolone, and these metabolites may be detected in urine.