First discovered in 1967, Tren was originally created for veterinary use, being injected into cattle approximately six weeks before slaughter. The enhanced ability of Trenbolone to synthesize protein allowed the animals to pack on muscle and bulk very rapidly. However, the possibilities that it offered for humans were also identified and the drug was marketed by Roussel AG from Germany until the 1980s. At that time, two out of the three possible variants of the drug were removed from the human market, with the third one following suit around a decade or so later. The FDA never gave it formal approval for use on humans. Although it is a derivative of Nandrolone, it is a unique compound because it is available in three different esters. These are: Trenbolone Acetate, Trenbolone Enanthate, and Trenbolone Hexhydrobenzylcarbonate
The latter is most commonly known as Parabolan and although it remains a variant of Tren, is often regarded as a separate entity.