Stanozolol, commonly sold under the name Winstrol (oral) and Winstrol Depot (intramuscular), is a synthetic anabolic steroid derived from dihydrotestosterone. It was developed by Winthrop Laboratories (Sterling Drug) in 1962, and has been approved by the FDA for human use.
Unlike most injectable anabolic steroids, stanozolol is not esterified and is sold as an aqueous suspension, or in oral tablet form. The drug has a high oral bioavailability, due to a C17 α-alkylation which allows the hormone to survive first-pass liver metabolism when ingested. It is because of this that stanozolol is also sold in tablet form.
Stanozolol has been used in both animal and human patients for a number of conditions. In humans, it has been demonstrated to be successful in treating anaemia and hereditary angioedema. Veterinarians may prescribe the drug to improve muscle growth, red blood cell production, increase bone density and stimulate the appetite of debilitated or weakened animals.
Stanozolol is one of the anabolic steroids commonly used as a performance enhancing drug and is banned from use in sports competition under the auspices of the International Association of Athletics Federations (IAAF) and many other sporting bodies. Additionally, stanozolol has been used in US horse racing.