Bro, almost every steroid is a derivative of testosterone but that does not mean they act like testosterone in the body...a simple google search came up with the following from Wikapedia:
"Nandrolone is an anabolic steroid occurring naturally in the human body, albeit in small quantities. Nandrolone is most commonly sold commercially as its decanoate ester (Deca-Durabolin) and less commonly as a phenylpropionate ester (Durabolin).
Nandrolone binds to the androgen receptor to a greater degree than testosterone, but due to its inability to act on the muscle in ways unmediated by the receptor, has less overall effect on muscle growth. The drug is also unusual in that unlike most anabolic steroids, it is not broken down into the more reactive DHT by the enzyme 5α-reductase, but rather into a less effective product known as Dihydronandrolone. As such, some of the negative effects associated with most such drugs are somewhat mitigated.
The positive effects of the drug include muscle growth, appetite stimulation and increased red blood cell production and bone density. Clinical studies have shown it to be effective in treating anaemia, osteoporosis and some forms of neoplasia including breast cancer, and also acts as a progestin-based contraceptive. For these reasons, in the United States nandrolone received FDA approval in 1983, and while sale in the U.S. is now restricted by the Controlled Substances Act, nandrolone remains available by prescription in most countries which have not adopted American-style "War on Drugs" anti-steroid campaigns. In addition to legal production, Nandrolone is also extensively used by bodybuilders and other athletes seeking an edge in professional competition.
Because nandrolone is not broken down into DHT, the deleterious effects common to most anabolic steroids on the scalp, skin, and prostate are lessened to a degree. The lack of alkylation on the 17α-carbon drastically reduces the drug's liver toxicity. Estrogenic effects resulting from reaction with aromatase are also mitigated as a result of the drug being a progestin, but effects such as gynaecomastia and reduced libido still occur in larger doses. Other side-effects can include erectile dysfunction (coined as "Deca Dick") and cardiovascular damage, as well as several ailments resulting from the drug's effect of lowering levels of luteinizing hormone through negative feedback."
"Trenbolone is a steroid used by veterinarians on livestock to increase muscle growth and appetite. To increase its effective half-life, trenbolone is not used in an unrefined form, but is rather administered as trenbolone acetate (Finaplix Gold from Valopharm USA, TREMBLONA QV75 from Quality Vet, Mexico), Trenbolone enanthate or Trenbolone cyclohexylmethylcarbonate (Parabolan from Laboratoires NEGMA until 1997). Plasma lipases then remove the ester in the bloodstream leaving the trenbolone base.
No trenbolone compounds have been approved by the FDA for human use, due to a lack of clinical applications and some potential negative side-effects. It is classified as a Schedule III drug under the Controlled Substances Act. However, bodybuilders have been known to use the drug illicitly in order to increase body mass more effectively than by weight training alone. A normal bodybuilding dosage can range from 200 mg/week up to 1400 mg/week. Due to the relatively short metabolic half-life of trenbolone acetate, dosages should commonly be split into injections at least once every two days. Trenbolone enanthate can be injected once a week.
The 2006 book Game of Shadows alleges that baseball superstar Barry Bonds used this drug in 2001, when he set the current single-season home run record.
Trenbolone acetate is often referred to as "Fina" by illicit users, because injectible trenbolone acetate is often prepared from Finaplix H pellets, an ear-implant used by cattle ranchers to maintain the weight of cattle during shipping to slaughter.
Trenbolone compounds have a binding affinity for the androgen receptor three times as high as that of testosterone. Once metabolised, the drugs have the effect of increasing nitrogen uptake by muscles, leading to an increase in the rate of protein synthesis. It also has the secondary effects of stimulating appetite, reducing the amount of fat being deposited in the body, and decreasing the rate of catabolism. Trenbolone has proven popular with anabolic steroid users as it is not metabolised by aromatase or 5α-reductase into estrogenic compounds such as estradiol, or into DHT. This means that it also does not cause any water retention normally associated with highly androgenic steroidal compounds like testosterone or methandrostenolone. It is also loved by many for the dramatic strength increases commonly experienced with it.
Short-term side effects include insomnia, high blood pressure, increased aggression, night sweats, and libido. However, since women will suffer virilization effects even at small doses, this drug should not be taken by a female. Urban wisdom/myth in bodybuilding culture, states that the use of the drug over extended periods of time can lead to kidney damage. The kidney toxicity has not yet been proven, and scientific evidence supporting the idea is suspiciously absent from the bodybuilding community that perpetuates this idea. The origin of this myth most likely has to do with the rust colored oxidized metabolites of trenbolone which are excreted in urine and often mistaken for blood. After Schänzer (Clin Chem 1996; 42(7): 1001-1020, Metabolism of anabolic androgenic steroids) trenbolone and 17epi-trenbolone are both excreted (in urine) as conjugates that can be hydrolyzed with beta-glucuronidase. This implies that trenbolone leaves the body as beta-glucuronides or sulfates, that means mostly non metabolized."