Testosterone Enanthate is not only the most popular derivative of Testosterone but also the most used steroid of all time. Synthetic testosterone was developed in the 1930’s. However, there were no esters attached, the drug was fast acting, and required very frequent injections. Very soon after that, the first ester that controls testosterone was introduced to the market, this was Testosterone Propionate. This ester allowed control over the testosterone hormone by regulating its time release. Testosterone Propionate’s half-life is only 2-3 days and still requires enough frequent injections for patients with low testosterone levels, which is why pharmaceutical companies continued working on creating new esters. In the 1950’s, a larger ester, Enanthate was attached to the testosterone hormone thus slowing down its activity.