Natural steroidal hormones (testosterone, estrogens, glucocorticoids, etc.) have been used historically to treat certain cancers, but because they were biologically active in their normal hormone pathways, their use has often been limited by undesirable side effects. GTx designed its SARMs to produce the beneficial effects of natural androgen hormones in cancer treatment, while minimizing the undesirable side effects.
The metabolism of natural steroids involves chemical reactions that change these molecules into other related molecules. This is one cause of the undesirable side effects that can be circumvented by treatment with our SARMs. Several enzymes (such as CYP19 aromatase and 5-alpha-reductase) are present in the body to convert androgen hormones to other hormones, including estrogen. Because these converted hormones control different bodily systems, it is easy to see that using androgens to target a bodily system specific to that androgen can inadvertently affect other systems.