http://www.steroidal.com/steroid-profiles/trenbolone/trenbolone-acetate/ said:
Trenbolone Acetate (commonly abbreviated as Tren Ace, Tren A, or simply as Tren) is the most popular format of Trenbolone in use by bodybuilders and athletes today. Initially, Trenbolone was officially released for a very brief period onto the human prescription market as Trenbolone Hexahydrobenzylcarbonate under the brand name Parabolan, which was manufactured in France. Parabolan was the first and only form of Trenbolone to be ever manufactured and sold for human use. This was for a very short period during the 1990s, however, and towards the late 1990s it was pulled from the market and Trenbolone itself was officially disapproved for human use. To this day, Trenbolone is still only officially utilised as a veterinary medicine exclusively for the purpose of promoting and preserving lean mass in livestock and cattle. It is not currently approved for human use anywhere in the world, but it is under current investigation in clinical studies as a more selective anabolic steroid than others, giving it the potential for medical application[1]. This is therefore a strong indication that Trenbolone might soon see re-entry into the human prescription drug market and re-approval for human use, though it is unknown how long it might be before this happens.