Steroids are classified into two different types, oral and injectable. Oral Steroids make it harder for the liver to degrade the steroid. Although the steroid can still be degraded, it is not as effective as the unmodified steroid. Because of this, oral steroids make several cycles through the bloodstream before they are excreted. Most steroids are excreted from the body unchanged to various degrees.
Injectable Steroids are effectively degraded with just one pass through the liver. With the injectable steroid allows a regular release of steroid into the bloodstream. As the steroid is removed from the bloodstream by the liver, more steroid is being released.
Suspension is a way to use pure testosterone. Testosterone has a low solubility in water, and the crystals slowly dissolve in the watery area of the tissue in which it is injected. The testosterone is carried throughout the body by the bloodstream.
Esters is another way to provide a depot of steroid by using a water- insoluble form of the steroid that can be converted in the body to the parent steroid which has some solubilityin water, which is the bloodstream. It is believed that esters form a depot of oil that stys at the injection site.
When the steroid has been released from the depot, it will be transported throughout the body in the bloodstream.