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 . 
Most who supplement with Arimidex will be doing so for the prevention of side-effects while on cycle or to tighten up their physique for a physique based competition by reducing estrogen in the body. Most men will find every other day to be a good starting point while on cycle if it is needed for side-effect prevention with 1mg every other day generally being the most anyone will ever need for this purpose. However, if side-effects begin to manifest, particular Gynecomastia, many find supplementing with 1mg every day for a few weeks to be useful in combating this enemy; however, for this purpose we would in most cases recommend the slightly stronger AI Letrozole but Arimidex will often suffice. If this occurs, simply supplement with 1mg every day until symptoms pass; once they do drop the dose to every other day and finish your intended cycle. It should be noted, this is not a 100% failsafe plan; for some no amount of any AI on earth will protect from Gynecomastia.
Drugs such as Nolvedex bind to the oestrogen receptors , therefore reducing the effects of the heightened oestrogen in the body. Such drugs do nothing to reduce the amount of oestrogen in the body; they merely reduce its effects via competition for the receptors . If the user wishes to reduce the amount of oestrogen they should look to drugs such as proviron and anastrozole , which are known as anti-aromatases - . they lower the conversion of the steroid to oestrogen and therefore reduces the overall amount of oestrogen present.