The most commonly used AAS in medicine are testosterone and its various esters (but most commonly testosterone undecanoate , testosterone enanthate , testosterone cypionate , and testosterone propionate ),  nandrolone esters (most commonly nandrolone decanoate and nandrolone phenylpropionate ), stanozolol , and metandienone (methandrostenolone).  Others also available and used commonly but to a lesser extent include methyltestosterone , oxandrolone , mesterolone , and oxymetholone , as well as drostanolone propionate , metenolone (methylandrostenolone), and fluoxymesterone .  Dihydrotestosterone (DHT; androstanolone, stanolone) and its esters are also notable, although they are not widely used in medicine.  Boldenone undecylenate and trenbolone acetate are used in veterinary medicine . 
Dragon Pharmaceutical Inc. is an international biopharmaceutical corporation engaged in the discovery, development and commercialization of genetically engineered human proteins for therapeutic use. Based on its proprietary protein expression technology, Dragon believes that it has become one of the world’s most competitive producers of Erythropoietin (EPO) a breakthrough drug that has revolutionized the treatment of anemia. Dragon is also applying its platform technology to the development of other generic and novel protein drugs.
Another intriguing difference lies in the effect on Sex Hormone Binding Globule (SHBG). SHBG is a naturally produced glycoprotein that binds to testosterone, making it unavailable for purposes such as building muscle. StanoGen is able to cause a lowering of SHBG and therefore free up more testosterone within the body. However, due to oral StanoGen having to first pass through the liver (where SHBG is produced), whereas injectable StanoGen doesn’t have to complete this first pass, oral StanoGen has a greater effect on lowering SHBG levels , and freeing up more testosterone.