Dopeology

Clenbuterol is classified as a sympathomimetic amine, meaning that it is a synthetic substance analogous to natural neurotransmitters (such as adrenaline) that act on the sympathetic nervous system.

Medically, its value is primarily as a bronchodilator, enabling asthma patients to breathe more easily, but it is most likely to be used by athletes to accelerate weight loss. While it is not approved for human use in some countries, where it tends nevertheless to be used on livestock, Clenbuterol is readily available elsewhere.

Testing

Clenbuterol is excreted from the body in the urine and can thus be detected by analysis using such technology as mass spectrometry.

Currently the most sensitive equipment is capable of detecting Clenbuterol concentrations as low as 5-10pg/ml in the urine, but WADA only requires that an accredited laboratory be able to detect a level as low as 2ng/ml (a picogram (pg) is one-trillionth of a gram; whilst a nanogram (ng) is one billionth of a gram).

A typical dose used by an athlete might be in the range of 50-100µg (microgram, one millionth of a gram) or higher, and under these conditions, Clenbuterol may be detected in the urine for a week or longer after it was last consumed.

Controversy

Since Clenbuterol is used on livestock to increase the proportion of lean meat, it can potentially be consumed by humans without their knowledge. In Europe, meat sold for human consumption is required to have a level of Clenbuterol less than 100ng/kg but elsewhere - particularly in China, Mexico and the Latin American region - standards may not be enforced.

Thus athletes who have tested positive for this substance in recent times have argued that their ingestion of this substance was accidental rather than the result of intentional doping.

Some scientists believe that this uncertainty might be alleviated by instituting a threshold for Clenbuterol — a level below which a positive would not be considered doping — but WADA has announced that it has no plans to change the status of the drug.

The current situation therefore remains: the outcome of each case is determined by whether or not an athlete can successfully argue that the evidence supports the conclusion that ingestion resulted from contaminated food.

Such evidence might include the location in which the meat was obtained or a hair test since Clenbuterol, like many other substances, accumulates in very small amounts in hair follicles. If an athlete has taken the substance over a period of time in the past, his/her hair test might return a positive for a period of six months or longer. Conversely, if the Clenbuterol resulted from a single incident, in which the subject had eaten meat for example, a hair test would almost certainly be negative.

Contributor: Andy Smith