Performance enhancing drugs are used by athletes in an attempt to improve strength, endurance, quickness and resilience to injury. While some of these drugs are approved for other purposes, or are synthetic forms of naturally-occurring substances in the body, they may still cause harmful and serious side effects.
Anabolic and Androgenic Agents
Anabolic agents are those that promote the growth of muscle, while androgenic agents are those that promote the development of male characteristics such as a deep voice and facial hair. Testosterone is an anabolic-androgenic steroid found naturally in the body that may also be taken by some to boost athletic performance, according to the Mayo Clinic. Other anabolic-androgenic drugs that can be taken orally, injected or applied topically include methyltestosterone, oxandrolone and oxymetholone. The Mayo Clinic advises that a particularly dangerous group of “designer” performance enhancing drugs that have received no safety testing include tetrahydrogestrinone, desoxymethyltestosterone and norbolethone.
According to the World Anti-Doping Agency, other anabolic agents include tibolone, zeranol, selective androgen receptor modulators, zilpaterol and clenbuterol.
Hormones and Hormone Antagonists
A number of synthetic hormones may be used in an attempt to increase physical strength or stamina. Erythropoiesis-stimulating agents are drugs that stimulate the production of red blood cells in the body. They are similar in structure and function to the protein erythropoietin that naturally occurs in the body and facilitates red blood cell production. These drugs include synthetic erythropoietin, or EPO, darbepoetin, or dEPO, methoxy polyethylene glycol-epoetin beta and hematide.
Among males, chorionic gonadotrophin, luteinizing hormone and corticotrophins--hormones that increase production of male sex hormones and other hormones that affect the balance of electrolytes in the body--are also performance enhancing hormones. Certain insulins and growth hormones may also be used to influence athletic performance. These include insulin-like growth factor-1 (IGF-1), growth hormone (GH), platelet-derived growth factor (PDGF), mechano growth factors (MGFs), fibroblast growth factors (FGFs), hepatocyte growth factor (HGF) and vascular-endothelial growth factor (VEGF), according to the World Anti-Doping Agency. In a process sometimes referred to as “blood spinning,” some people may also inject specially-prepared platelet-rich plasma preparations high in growth hormone into the muscle to shorten healing time from injuries.
Hormone antagonists are drugs that block the normal functioning of certain hormones in the body. Aromatase inhibitors such as aminoglutethimide, androstatrienedione, anastrozole, exemestane, letrozole, formestane, testolactone and 4-androstene-3,6,17 trione (6-oxo) work by stopping the production of estrogen in the body. Selective estrogen receptor modulators like raloxifene, toremifene and tamoxifen and anti-estrogenic drugs such as cyclofenil, fulvestrant and clomiphene also block the effects of estrogen in specific body locations. Myostatin inhibitors are also considered to be performance-enhancing drugs, blocking the effects of hormones responsible for regulating muscle mass.
Diuretics and Masking Agents
Diuretics alter the balance of naturally-occurring minerals such as sodium and potassium in the body, flushing the body of excess water. This can lead to weight loss and can also dilute the urine and mask the effects of other illicit drug use. According to the World Anti-Doping Agency, diuretics include furosemide, amiloride, triamterene, spironolactone, canrenone, indapamide, bumetanide, acetazolamide, chlorthalidone, etacrynic acid, metolazone, and thiazides such as hydrochlorothiazide, bendroflumethiazide and chlorothiazide. Other masking agents sometimes used include probenecid and intravenous albumin, mannitol, dextran or hydroxyethl starch.
Creatine is a nutritional supplement available over-the-counter in powder or pill form. According to the Mayo Clinic, there is some evidence that creatine may help to delay muscle exhaustion and improve short bursts of muscular power; however, there is no data to suggest it improves aerobic or muscular endurance.