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.
As a C17-aa anabolic steroid, Winstrol is hepatotoxic and will present stress to the liver. A common misconception many make is assuming only the oral version of this steroid is hepatotoxic. Winstrol can be found as an oral tablet or as an injectable solution but both forms are C17-aa and both stressful to the liver. In fact, injectable Winstrol is one of the only C17-aa injectable steroids. Many also inaccurately assume this is one of the most hepatotoxic anabolic steroids on the market; again this is false. Stanozolol will carry a greater hepatotoxicity than steroids like Anavar (Oxandrolone) but on a per milligram basis less hepatotoxic than steroids like Dianabol (Methandrostenolone).
This is where it all started. The oral form was originally developed back in 1956 by Dr. John Ziegler and Ciba labs. This was the first steroid used by American athletes and was the only steroid anyone in this country talked about until the late 1970’s, by which time it had earned the nickname, “the breakfast of champions;” a sly wink at 1971 Kurt Vonnegut satire about depravity in the modern age—that and the fact several pro-football clubs greeted their players each morning with breakfast and those little pink pills. Methandrostenolone is by far the most popular steroid used by athletes. Ciba labs discontinued the brand name Dianabol in USA during the 1990’s because the FDA decided the only people using this drug were athletes. Dianabol pictures: