Stanozolol (also known as winstrol) is a 17-alpha-alkylated derivative of dihydrotestosterone (DHT) with low androgenic qualities yet highly anabolic. It was first developed in 1962 by the American global pharmaceutical company Sterling-Winthrop Laboratories to increase lymphocyte count and CD8+ cell numbers, but to decrease CD4+ and CD3+ in postmenopausal women using it for osteoporosis.