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 . 
Ingested formula components arrive intact to intestinal villi, thanks to the protection of the enteric layer and from there go into the bloodstream to be selectively incorporated by the cells via various means of cellular transport, depending on the size of molecules such components. Large molecules are incorporated by endocytosis and the smaller molecules are incorporated by simple diffusion or diffusion provided by receptor proteins, as appropriate.
The useful parts of the cell extracts are recycled and used in cells. The parts that are not useful are eliminated and expelled outside the cell.
The incorporation of the various components to the corresponding cell tissues is facilitated by the empathy developed by Biocell Laboratories between these components and the receptor proteins on the cell membrane surface.