Because the ultimate goal of a steroid cycle is to increase strength and muscle size, the associated spike in estrogen which accompanies steroids such as Testosterone is considered undesirable. In order to disassociate the two effects, two classes of drug are used. Medications such as Nolvadex or Clomid target the estrogen receptors. They make it more difficult for the estrogen to exert it’s influence within the body thus allowing the testosterone to act more freely. The second class is aromatase inhibitors such as Femara. They target the aromatase enzyme itself in order to prevent the production of estrogen in the first place. Sometimes, it’s not always clear which option you should go with or even what the differences are between the two. Lets clear that up a little.
The oral bioavailability of oxandrolone is 97%.  Its plasma protein binding is 94 to 97%.  The drug is metabolized primarily by the kidneys and to a lesser extent by the liver .   Oxandrolone is the only AAS that is not primarily or extensively metabolized by the liver, and this is thought to be related to its diminished hepatotoxicity relative to other AAS.   Its elimination half-life is reported as to hours but is extended to hours in the elderly.   Approximately 28% of an oral dose of oxandrolone is eliminated unchanged in the urine and 3% is excreted in the feces .