Tibolone, also known as 7α-methylnoretynodrel, as well as 7α-methyl-17α-ethynyl-19-nor-δ 5(10) -testosterone or as 7α-methyl-17α-ethynylestr-5(10)-en-17β-ol-3-one, is a synthetic estrane steroid and a derivative of testosterone and 19-nortestosterone .   It is more specifically a derivative of norethisterone (17α-ethynyl-19-nortestosterone) and is a member of the estrane subgroup of the 19-nortestosterone family of progestins.     Tibolone is the 7α-methyl derivative of the progestin noretynodrel (17α-ethynyl-δ 5(10) -19-nortestosterone).  Other steroids related to tibolone include the progestin norgesterone (17α-vinyl-δ 5(10) -19-nortestosterone) and the anabolic steroids trestolone (7α-methyl-19-nortestosterone) and mibolerone (7α,17α-dimethyl-19-nortestosterone). 
Abstractly, trenbolone enanthate for injection , laid out on our Forum, marks the highest progestogenic activity of the product, lack of toxicity to the liver and flavoring. Enanthate ester after the injection is active in the body 1-3 days, uniformly decaying plasma lipase enzymes. Without joining ester steroid molecule simultaneously to completely exert their activity, which the athlete simply did not have time to use it. Artificially extended the time period of the active substance in the blood allows less frequent injections and constantly maintain the highest level of hormone in the blood.
Some bodybuilders and athletes use trenbolone esters for their muscle-building and otherwise performance-enhancing effects.  Such use is illegal in the United States and many other countries. The DEA classifies trenbolone and its esters as Schedule III controlled substances under the Controlled Substances Act .  Trenbolone is classified as a Schedule 4 drug in Canada  and a class C drug with no penalty for personal use or possession in the United Kingdom .  Use or possession of steroids without a prescription is a crime in Australia .