Some of the approved drugs are synthetic versions of the natural hormones, such as trenbolone acetate and zeranol. Just like the natural hormone implants, before FDA approved these drugs, FDA required information and/or toxicological testing in laboratory animals to determine safe levels in the animal products that we eat (edible tissues). Furthermore, FDA required that the manufacturers demonstrate that the amount of hormone left in each edible tissue after treatment is below the appropriate safe level. As described above, a safe level is a level which would be expected to have no harmful effect in humans.
It has some mild side effects associated with it as well. Side effects occur when you take it for a very long period of time and in more quantity. Major drawback of Anavar is that it is too costly, although available in black market but one cannot be so sure of the authenticity of it bought from there. As it is DHT and due to this hair loss and acne can occur. But hair loss only in men who have got this hair loss disease genetically transmitted. There could be high blood pressure and high cholesterol levels but only for those who are not living a healthy life style and these diseases are not transmitted genetically to the users as well. Due to the non aromatizing nature of Anavar it has taken side effects of water retention and Gynecomastia out of the equation.
Sex hormone-binding globulin (SHBG) is thought to mainly function as a transporter and reservoir for the estradiol and testosterone sex hormones. However it has also been demonstrated that SHBG can bind to a cell surface receptor (SHBG-R). The SHBG-R has not been completely characterized. A subset of steroids are able to bind to the SHBG/SHBG-R complex resulting in an activation of adenylyl cyclase and synthesis of the cAMP second messenger.  Hence the SHBG/SHBG-R complex appears to act as a transmembrane steroid receptor that is capable of transmitting signals to the interior of cells.