Bolasterone is an anabolic steroid. It is able to activate androgen receptor. Despite being a testosterone derivative, bolasterone is also much more anabolic than androgenic in nature. At a given therapeutic level, it is much less likely to cause androgenic/virilizing side effects. he drug was developed by Upjohn, and sold in the U.S. during the 1960's under the Myagen brand name. It was mainly indicated for the treatment of advanced breast cancer in women, although the agent was also investigated for its stimulatory effect on blood cells and its general anabolic (lean-tissue sparing) activity. Bolasterone was ultimately a short-lived drug, disappearing from the U.S. market shortly after its release.

Bolasterone:
https://drugs.ncats.io/drug/T7ZM08F7FU

Bolasterone was first discovered in 1959. It was closely evaluated for anabolic and androgenic effect approximately 3 years later. The drug was developed by Upjohn, and sold in the U.S. during the 1960's under the Myagen brand name. It was mainly indicated for the treatment of advanced breast cancer in women, although the agent was also investigated for its stimulatory effect on blood cells and its general anabolic (lean-tissue sparing) activity. Bolasterone was ultimately a short-lived drug, disappearing from the U.S. market shortly after its release. By the 1980's, bolasterone had been out of commerce for so long that it was all but forgotten among athletes. Bolasterone is no longer produced.

Excerpt from Steroids World:
https://steroids.world/myagen-bolasterone

Bolasterone:

• An anabolic steroid
• Used in veterinary medicine
• It has close structural similarity to testosterone
• It has a low to moderate ratio of anabolic to androgenic activity, similar to that of fluoxymesterone.

Bolasterone is on the World Anti-Doping Agency's list of prohibited substances, and is therefore banned from use in most major sports