Boldenone (1,4-androstadiene-3-one-17β-ol, available as the undecylenate ester), also known under the trade names Equipoise, Ganabol, Equigan and Ultragan, is an anabolic steroid developed for veterinary use, mostly for treatment of horses.
The activity of boldenone is mainly anabolic, with a low androgenic potency. Boldenone will increase nitrogen retention, protein synthesis, increases appetite and stimulates the release of erythropoietin in the kidneys. Boldenone was synthesized in an attempt to create a long-acting injectable methandrostenolone (Dianabol), but in reality boldenone acts nothing like methandrostenolone. It has a very long half-life, and can show up on a steroid test for up to 1.5 years, due to the long undecylenate ester attached to the parent steroid. Trace amounts of the drug can easily be detected for months after discontinued use. Although commonly compared to nandrolone, boldenone lacks progesterone receptor interaction and all the associated progestogenic side effects.