Trenbolone Enanthate is a drug that’s exclusive to the underground market. In other words, you won’t see it with the Organon or STERIS label on it. It was produced as a cheaper alternative to Parabolan, by a leading underground lab several years ago. When I first got my hands on it, I sent it away to a large lab to have it tested for purity and although they replied that it was probably about 90% pure, they couldn’t be totally sure because they had no test sample to compare it to. So what’s really interesting here, from a philosophical point of view, is that the underground actually began to produce their own unique products instead of simply producing clones of the steroids already available at the pharmacy. Other than the ester, which only effects the blood plasma levels of a steroid, peak concentration, and active life, this drug is identical to Parabolan and Trenbolone Acetate- differing only in the fact that it is active in the body for a longer time. Therefore, injections with this compound are typically once or twice per week.
Trenbolone is derived from 19-nor Testosterone, but with three additional bonds- making it unable to aromatize (convert) to estrogen, as well as making it not subject to 5a-reduction (conversion to a Dihydro form). Speaking from a structural standpoint, Trenbolone is actually very similar to Deca-Durabolin (Nandrolone Decanoate), except for a c-9 and c-11 double bond. These two double bonds are very important, however, and provide Trenbolone with several important differences. Firstly, the c9 bond serves to prevent aromatization (conversion) to estrogen, while the c11 double bond seems to increase Androgen Receptor binding quite profoundly (although this may also have something to do with the c9 bond as well). Thus, as compared with Deca, Trenbolone’s lack of estrogenic activity and potent ability to bind to the androgen receptor allow it to be a much stronger anabolic/androgenic agent than Deca Durabolin. So what we see in Trenbolone is a drug that’s roughly 4x as anabolic as Deca, and roughly 10x as androgenic (according to the Vida Reference scale). With Trenbolone, the majority of weight gained on this drug is lean and quality muscle.
Trenbolone also has the advantage of significantly increasing the level of the hormone IGF-1 (which is highly anabolic) within muscle tissue.
 Not only does it increase the levels of IGF-1, substantially, it also causes increased sensitivity to it
. This is true of many steroids, such as Testosterone, and many others. However, if we compare Trenbolone to Testosterone, we additionally see that it’s binding affinity to the androgen receptor (AR) is significantly stronger
. Strong androgen receptor binding is a major contributing factor in anabolism as well as fat loss.
Trenbolone Enanthate (or any form of Trenbolone) aids anabolism by promoting nitrogen retention and protein synthesis in muscles  and it seems to interact strongly with the receptors of anti-anabolic (muscle growth preventing) glucocorticoid hormones . This will reduce cortisol  and aid in muscle growth. Due to these protein synthesizing effects, it can aid your feed efficiency and mineral absorption  which will make food you eat more productive in building new muscle tissue, and makes it a very effective agent with regards to nutrient partitioning , which is how your body metabolizes foodstuffs.
Since Trenbolone binds so tightly to androgen receptors, and those receptors are found in lipid cells as well as muscle cells , Trenbolone seems to have a profound effect on the AR in both of these types of cells to catalyze anabolism as well as lipolysis (fat-burning). Finally, Trenbolone significantly promotes red blood cell production and also increases the rate of glycogen replenishment, both of which serve to profoundly improve recovery. 
The most common complaint with Trenbolone is that it can reduce aerobic capacity possibly due to bronchial dilation from increased prostaglandin formation. However at least in most users, since the blood levels of Trenbolone Enanthate won’t spike as rapidly or peak to as high of a level as quickly as we see with the Acetate version- this effect is not as pronounced with the Enanthate version. Thus the infamous “Tren Cough” many users complain about with the Acetate version isn’t as common with the Enanthate ester.
Doses are usually in the 200-600mg/week range, and since the ester length of this steroid is reasonably long, it only needs to be administered via intramuscular injection once or twice a week. Of course, it is equally useful in both cutting as well as bulking cycles.
The principal drawback to Trenbolone Enanthate is that it can be quite costly.