Trenbolone is a modified form of nandrolone. It differs by the introduction of double bonds at carbons 9 and 11, which inhibit aromatization (9-ene), increase androgen binding affinity, and slow its metabolism. The resulting steroid is significantly more potent as both an anabolic and an androgen than its nandrolone base. The trenbolone here is modified with an enanthate ester at the 17-beta hydroxyl group, so that the free steroid released more slowly from the area of injection. Given the enanthate ester this drug will exhibit virtually identical pharmacokinetics to testosterone enanthate, providing a peak release of its steroid within the first several days after injection, followed by declining level for approximately 2 weeks. Among athletes, trenbolone is highly valued for its ability to increase muscle hardness, definition, and raw strength, without unwanted water retention and fat mass gains. It is a drug of choice for contest bodybuilders, yet remains very popular with recreational users looking to refine their physiques. Trenbolone enanthate was never approved for use in humans so prescribing guidelines are unavailable. An effective dosage for physique or performance enhancing purposes generally falls in the range of 100-400mg per week.