ANABOLIC AGENTS
Two groups of drugs fall into the category, the anabolic androgenic steroids and the beta-2-agonists.

Anabolic androgenic steroids
Anabolic steroids include nandrolone, oxandrolone, stanozolol, testosterone, metenolone, dehydroepiandrosterone (DHEA) and related substances. Over 100 different anabolic steroids are available. Testosterone is responsible for stimulating development of male sexual characteristics (androgenic effect) and the build up of muscle tissue (anabolic effect). Manufacturers of anabolic steroids aim to minimise the androgenic and maximise the anabolic effects. They improve performance by increasing muscle size and strength, allow athletes to train harder and longer, with improved recovery from training sessions and promote increased aggression and competitiveness. Anabolic steroids are known as 'training drugs' as they are often taken during training prior to competition and then stopped for several weeks before a competition to reduce the likelihood of positive testing. The presence of testosterone (T) to epitestosterone (E) in the urine in a ratio of greater than 6:1 constitutes an offence unless there is evidence that the ratio is due to an underlying physiological or pathological disorder. Side-effects of anabolic steroid abuse include: hypogonadism, gynaecomastia, acne, alopecia, stunted growth in teenage athletes, male and female infertility, aggression, cholestasis, cardiovascular disease and death.

Beta-2-agonists
Beta-2 agonists are not anabolic steroids, however they do have potent anabolic effects, Drugs such as salbutamol and clenbuterol, when taken orally, increase muscle mass improving muscular strength. Clenbuterol ("angel dust"), only available as a veterinary medicine, is also widely abused in the cattle industry. Salbutamol, salmeterol and terbutaline are permitted by inhalation, with written notification in advance of competition; the same applies to inhaled steroids. Asthmatics may be treated with therapeutic doses of theophylline, sodium cromoglycate and anticholinergics without prior medical notice.

DIURETICS
Diuretics e.g. frusemide, bumetanide, chlorthalidone, triameterene, hydrochlorothiazide tend to be abused by those competing in weight classes e.g. weight lifiting, boxing, wrestling and horse-racing, to achieve rapid weight loss. Diuretic use prior to weigh-ins has been associated with serious adverse effects, such as profound hypotension and in one case pulmonary embolism. They are also used to enhance exertion of prohibited drugs to mask their presence in the urine by producing a significant dilution.

PEPTIDE HORMONES
Peptide hormones are the so-called sports designer drugs and are increasingly abused by athletes. Their attraction is that although they are synthetically produced, they are indistinguishable from the body's natural hormones and cannot be detected by current IOC testing methods. Human chorinonic gonadotrophin (HCG) is used to stimulate the production of endogenous testosterone. Human growth hormone (HGH), a particularly expensive drug, is also thought to have an anabolic effect. Recent data from studies in weight lifters however suggest that although it increases lean body mass, it does not significantly increase muscular strength. Side-effects associated with its abuse include acromegaly, gigantism and metabolic disturbances. Creutzfield-Jacob disease has been associated with some eastern European supplies of HGH. A detection method for HGH is currently under development. Insulin is also being abused, with potentially fatal consequences.

Some athletes are putting their lives at risk by taking erythropoietin (EPO). EPO stimulates red blood cell production from the bone marrow. Synthetically prepared EPO (Eprex) is used medically to increase the haematocrit of patients with severe anaemia associated with chronic renal failure. It increases haemoglobin levels thereby increasing packed cell volume (PCV) and improving oxygenation of the blood. Eprex is being used in sport to enhance oxygen delivery to working muscles and improve athletic endurance. Abuse of EPO can increase the haematocrit in endurance athletes to very high levels. The viscosity of the blood is greatly increased which can lead to poor circulation, thrombotic lesions and myocardial infarction. It is thought that the high incidence of sudden death in some endurance athletes is due to abuse of EPO now considered to be perhaps the most deadly of the ergogenic drugs available.

Prohibited Methods

BLOOD DOPING
Blood doping is also used to improve the oxygen capacity of the ahtlete's blood. It constitutes the administration of blood and red blood cells, usually preceded by withdrawal of the blood from the athlete who continues to train in a blood depleted state. The athlete's blood is stored and later reinfused, thereby boosting the PCV. Again this method is difficult to detect. Due to the difficulties associated with appropriate storage and reinfusion of blood, this method is being superseded by administration of EPO, as described above.

PHARMACOLOGICAL, CHEMICAL AND PHYSICAL MANIPULATION
The drug testing procedure may be manipulated by pharmacological, chemical and physical means and such procedures are also banned. A number of methods are used for tampering with the integrity and validity of urine samples collected for testing. Physical procedures include catheterisation and instillation of clean urine into the bladder, followed by simulation of voiding. Pharmacological means include the use of probenecid to inhibit renal excretion of steroids. Epitestosterone is also added to the urine to reduce the T/E ratio.
Drugs Subject to Certain Restrictions

A number of drugs are subject to certain restrictions and others are prohibited by some sports authorities only.

For example, corticosteroids may be given topically (i.e. nasal, ophthalmic, aural, anal, dermatological) and via inhalation and intraarticular injection, but only with prior written notification to the appropriate authority.

Local anaesthetics are also permitted under predefined conditions, except for dental use.

Betablockers reduce anxiety and tremor and so are banned in control sports such as shooting, archery, bowls, skijumping and synchronised swimming

Nutritional Supplements

Many athletes use ergogenic nutritional aids to benefit performance without damaging their eligibility for competition or indeed their health. Substances promoted as beneficial include carnitine, chromium picolinate and creatine.

Many products are promoted as natural anabolic steroids, and advertised in lifestyle magazines, health food stores and more recently on the Internet. However, despite their widespread promotion, many claims are unsubstantiated and there is little evidence of benefit.

In addition, purified amino acids are also taken as a rich protein source. Some products may also be harmful. Excessive intake of protein may cause liver and kidney damage. Hypervitaminosis is not uncommon.

Creatine is currently in vogue and actively promoted by coaches, but again there is limited evidence of improved performance. Chromium picolinate is a food supplement claimed to accelerate lean body mass and concurrent loss of body fat. It is particularly popular with weightlifters and bodybuilders. Recent studies have failed to confirm any significant effects on muscular development and strength. Analogues of picolinic acid are known to affect metabolism of serotonin, dopamine and noradrenaline metabolism. Chronic renal failure has also been associated with ingestion of this supplement.

High doses of sodium bicarbonate are taken by some athletes to enhance performance. Often referred to as soda doping it involves ingestion of up to 3 mg/kg sodium bicarbonate, approximately 30 minutes before exercise. The excess alkaline load buffers the lactic acid in the blood produced from fatigued muscles. The leg muscles are most susceptible to lactic acid accumulation. Hence the popularity of soda doping with competitive cyclists and sprinters.

Ingestion of such high doses of alkaline salts is not without side effects. Fluid retention and abdominal bloating are common, as is thirst. Severe GI discomfort may occur and the excess sodium load may place undue strain on the heart. Alkalination of the urine also prolongs the halflife of prohibited substances such as amphetamines and pseudoephedrine, thereby enhancing their toxicity.

Summary

The use of performance enhancing drugs in sport contravenes the spirit of fair competition and can also be detrimental to an athlete's health. Many feel that a drug must be taken to level the playing field and for some "it is just one step from the belief that drugs can aid performance to the expectation that athletes must take drugs if they want to win medals". However, where some athletes deliberately take drugs to seek an advantage, others may inadvertently take a prohibited substance due to a lack of awareness.

Nevertheless, drug doping is here to stay and effective doping control methods must be in place, supported by education, of both athletes and health care professionals, quality research and international collaboration.