Oxandrolone, also known as oxandrin, is a drug first synthesized by Raphael Pappo while at Searle Laboratories, now Pfizer Inc., under the trademark Anavar, and introduced into the United States in 1964. It is a synthetic anabolic steroidderivative of dihydrotestosterone with an oxygen atom replacing the 2 carbon and methylation in the 17 position
Oxandrolone is widely used due to its exceptionally small level of androgenicity accompanied by moderate anabolic effect. Although oxandrolone is a 17-alpha alkylated steroid, its liver toxicity is very small as well. Studies have showed that a daily dose of 20 mg oxandrolone used in the course of 12 weeks had only a negligible impact on the increase of liver enzymes. As a DHT derivative, oxandrolone does not aromatize (convert to estrogen, which causes gynecomastia or male breast tissue). It also does not significantly influence the body's normal testosterone production (HPTA axis) at low dosages (20 mg). When dosages are high, the human body reacts by reducing the production of LH (luteinizing hormone), thinking endogenous testosterone production is too high; this in turn eliminates further stimulation of Leydig cells in thetesticles, causing testicular atrophy (shrinking). Oxandrolone used in a dose of 20 mg/day suppressed endogenous testosterone by 67% after 12 weeks of therapy.
In a randomized, double-blind study, patients with 40% total body surface area burns were selected to receive standard burn care plus oxandrolone, or without oxandrolone. Those treated with oxandrolone showed improved body composition, preservedmuscle mass and reduced hospital stay time.
The drug was prescribed to promote muscle regrowth in disorders which cause involuntary weight loss, and is used as part of treatment for HIV/AIDS. It had also been shown to be partially successful in treating cases of osteoporosis. However, in part due to bad publicity from its abuses by bodybuilders, production of Anavar was discontinued by Searle Laboratories in 1989. It was picked up by Bio-Technology General Corporation, now Savient Pharmaceuticals who, following successful clinical trials in 1995, released it under the tradename Oxandrin.