Developed by the pharmaceutical firm Organon, Sustanon 250 is an oil-based testosterone blend. Sustanon 250 is an injectable steroid with four testosterone esters - propionate (30mg) phenylpropionate (60mg), isocaproate (60mg), and decanoate (100mg). Why the four esters?
Esters create a depot (thus some injectable steroids have "depot" on their names) on the site of administration, and from within the muscles the hormone is released in sustained manner. The role of esters is basically to make the synthetic hormones to resist immediate metabolism. Because of esters, the hormones are released steadily to prevent fluctuation in blood levels. The rate at which the hormones are released depends on the weight and length of the esters; some may take days, while some may take weeks. The longer and the heavier the ester attached, the longer the active life of the steroid.
In the case of Sustanon 250 , the propionate and the phenylpropionate esters have relatively shorter active lives. Propionate has only one to two days of active life while phenylpropionate has four to five days. Because of these two esters Sustanon 250 provides you immediate kick, so to speak. Isocaproate and decanoate, meanwhile, are longer-acting esters; these two ensure that the Sustanon 250 continues to exert tissue building active for a long time, oftentimes lasting for a month. Isocaproate and decanoate has active life of two and three weeks, respectively.
