1996 Chemist Patrick Arnold develops Androstenedione, the first pro hormone to be marketed to the public. This piqued the interest of the chemically inclined and experiments led to the manufacturing of increasingly potent prohormones, or hormone precursors that converted to testosterone, nandrolone, boldenone, and dihydrotestosterone (DHT).
1998 Mark McGwire draws the attention of not only baseball fans with home run record---but the FDA as well for his use of Androstenedione, inciting a new determination of researchers to expose this compound as an illegal form of anabolic steroids.
In the meantime, the original prohormone creator, Patrick Arnold, through his company Ergopharm developed and released the prohormone 1-AD, which converts in the body through digestion to 1-testosterone the most comparable substance to illegal steroids, exacting results similar to the well known illegal steroids such as Winstrol and Primobolan, and eventually determined to have a similar make up as the dangerous and illegal steroid Trenbolone Acetate.
Manufacturers took notice of the process behind pro hormones and found that the enzymatic breakdown resulted in a weak form of the desired hormone result. Supplements were now hitting the market in the highly concentrated form that was originally targeted through the enzyme process (remember that 1-AD converted into 1-testosterone? Now 1-testosterone was being sold—no enzymes needed)
This daring approach taken by manufacturers led to the eventual debut of methyl-1-testosterone (M1T) a form of hormone that was resistant to breakdown producing a substance that created a marked elevation of hormone levels within the blood begetting the consumer rapid anabolic gains, and strength comparable or even greater than results seen with illegal steroids. But this potent product was not without side effects, some which also exceeded those associated with anabolic steroids, namely high blood pressure, and critical elevation of liver enzymes indicating alarming damage.
2004 Though warned by manufacturers of less potent formulas, of the implications connected to these increasingly dangerous prohormones, an act was passed, the Anabolic Steroid Control Act of 2004 which effectively banned prohormones that were currently on the market, categorizing them with anabolic steroids.
2005 All applicable pro hormones defined by the law as illegal were removed from the market in the United States.