Sustanon 250 is made up of four testosterone esters, each having its own action duration. With its different testosterone variants, Sustanon 250 is designed for providing a gradual release of testosterone into the blood plasma, which is helpful in bringing down the frequency of dosage. Testosterone by itself, without any esters attached has a half-life in the range of 2-4 hours. However, when esters attach themselves to this natural hormone they slow down testosterone’s release. For example, with a Propionate ester attached to it, the resulting testosterone preparation has a half-life of days, which is significantly longer than normal testosterone’s half-life. The four esters of Sustanon 250 undergo hydrolysis, . are broken by the action of water, almost immediately after entering general circulation to leave the natural steroid hormone, testosterone, free in the bloodstream.
Lets look at an example. Your doctor has you on testosterone replacement. You are 45 and have had low test since the age of 40. This condition is very very common. Low testosterone has all sorts of negative health repurcussions. Normal testosterone levels are between 300 and 1100 ng. You want to be at around 1100.. Your doctor wants you around 700-800. To do so he prescribes exogenous test at 150 mgs/week. That amount puts your total test at 760 ng, and your fee test around 10. Adding Masteron increases your free test to 19, Your total test is the same, but your free test, the test you actually use, is much more.
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.