Testosterone can be administered parenterally , but it has more irregular prolonged absorption time and greater activity in muscle in enanthate , undecanoate , or cypionate ester form. These derivatives are hydrolyzed to release free testosterone at the site of injection; absorption rate (and thus injection schedule) varies among different esters, but medical injections are normally done anywhere between semi-weekly to once every 12 weeks. A more frequent schedule may be desirable in order to maintain a more constant level of hormone in the system.  Injectable steroids are typically administered into the muscle, not into the vein, to avoid sudden changes in the amount of the drug in the bloodstream. In addition, because estered testosterone is dissolved in oil, intravenous injection has the potential to cause a dangerous embolism (clot) in the bloodstream.
In the world of anabolic steroids we generally have two options; human grade and underground. Both forms can be found on the black market but human grade refers to those that are also available by way of a pharmaceutical purchase. Human grade steroids are made in the purest fashion; they are always dosed correctly and are always free from any problem that an underground brand might carry. It is true, you can absolutely buy Anadrol from an underground label that is both effective and clean but the odds are not in your favor. At one time there were many quality underground labs but those days are long gone and the strong majority are either scams or poor practicing and lazy manufacturers; there are still good ones but they are simply few and far between. To eliminate concern the obvious choice is to simply buy Anadrol from a human grade label; unfortunately though if you are purchasing on the black market youre not quite out of the water yet. Human grade brands are notorious for being counterfeited; after all, if youre going to counterfeit a product youre more than likely going to slap the best label on it. For this reason you need to do some digging and ensure you are only purchasing from reputable venues; we recommend and it is the only true recommendation we can give that you go to the doctor and acquire a legal prescription.