BACKGROUND: Clenbuterol: stimulant and anabolic accelerator

Sep 30, 2010, 14:48 GMT

Berlin - Originally designed as an asthma medication, clenbuterol is also misused among livestock and athletes.

The substance is a non-steroidal beta-2-agonist and officially a stimulant. It is part of medications for various breathing disorders, most notably asthma.

However, clenbuterol in high dosage also acts as an anabolic accelerator which leads to misuse in various areas.

Most notably, it raises the muscle-to-fat ratio. It is used illegally among livestock to get leaner meat. A German farmer was sentenced in the 1990s for using among 800 calves and several hundred people reportedly were poisoned by pork contaminated with clenbuterol in China four years ago.

Among athletes, the fat burner is also popular as it builds muscle mass and slows down the body's natural muscle degeneration.

German sprinter Katrin Krabbe was the first big-name athlete who tested positive for clenbuterol, back in 1992. Not a banned substance at the time, she was punished for misuse of medication.

The substance is now on the doping list and gained headlines again in recent years in several doping cases.

Among others, Polish canoeist Adam Seroczynsk, British hurdler Callum Priestley and German table tennis player Dimitrij Ovtcharov tested positive for clenbuterol before Tour de France winner Alberto Contador was named Thursday as the latest offender.

According to the World Anti-Doping Agency, 73 athletes were caught using clenbuterol in 2008 and 67 in 2009.

Contador is among those athletes who have blamed contaminated food or supplements for the positive test.