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.
Of concern to any user of Winstrol during a cycle should be its intoxicating effect on the liver . The drug is a 17aa structured steroid , meaning it has been structured in a way which allows it to be orally bio-available, yet this has the negative effect of making Winstrol potentially harmful to the liver. It is therefore paramount the duration of a Winstrol cycle is limited, the dose of the drug is not excessive, the user does not stack it with other hepatotoxic compounds, does not drink alcohol whilst on cycle, and does not use Winstrol if they have an underlying medical condition which effects the livers health. There are supplements available which also help protect the liver (Milk Thistle, Liv-52 etc), and these would be advisable during any Winstrol cycle .