Systematic (IUPAC) name
Clinical data
AHFS/ International Drug Names
Pregnancy cat. C
Legal status  ? (UK)
Routes oral
Pharmacokinetic data
Bioavailability 89-98% orally
Metabolism central nervous system
Half-life 36-39 hours
Excretion  ?
CAS number 37148-27-9
ATC code R03AC14 R03CC13 QG02CA91
PubChem CID 2783
DrugBank DB01407
ChemSpider 2681 YesY
KEGG D07713 YesY
ChEBI CHEBI:174690 YesY
Chemical data
Formula C12H18Cl2N2O 
Mol. mass 277.19
SMILES eMolecules & PubChem
 YesY(what is this?)  (verify)

Clenbuterol (trade names: Spiropent, Ventipulmin) is a sympathomimetic amine used by sufferers of breathing disorders as a decongestant and bronchodilator. People with chronic breathing disorders such as asthma use this as a bronchodilator to make breathing easier. It is most commonly available as the hydrochloride salt clenbuterol hydrochloride.


Effects and dosage

Clenbuterol is a β2 agonist with some structural and pharmacological similarities to epinephrine and salbutamol, but its effects are more potent and longer-lasting as a stimulant and thermogenic drug. It causes an increase in aerobic capacity, central nervous system stimulation, and an increase in blood pressure and oxygen transportation. It increases the rate at which body fat is metabolized, simultaneously increasing the body's BMR. It is commonly used for smooth muscle relaxant properties. This means that it is a bronchodilator and tocolytic.

Clenbuterol is usually used in dosages anywhere from 20-60 micrograms (mcg) a day when prescribed. A dose of about 120 mcg (women) or 140 mcg (men) should never be exceeded in a day.

Clenbuterol is also prescribed for treatment of horses; however, equine use is usually the liquid form of clenbuterol.

Human use

Clenbuterol is approved for use in some countries (via prescription only) as a bronchodilator for asthma patients.[1] Recently though, the drug has been publicized for its off-label use as a weight loss drug, similar to usage of other sympathomimetic amines such as ephedrine. It is commonly used as a slimming aid despite lack of sufficient clinical testing either supporting or negating such use.

Legal status

Clenbuterol is not an ingredient of any therapeutic drug approved by the U.S. Food and Drug Administration[1] and is now banned for IOC-tested athletes.[2] In the U.S., administration of clenbuterol to any animal that could be used as food for human consumption is banned by the FDA.[3]

Use as performance-enhancing drug

As a beta 2 sympathomimetic, clenbuterol has also been used as a performance-enhancing drug. In 2010, three cyclists were also accused of taking the drug. Three-time Tour de France champion Alberto Contador of Spain was suspended from cycling after testing positive for the drug at the 2010 Tour de France.[4] He has been cleared by the Spanish cycling federation, which canceled its January 26 proposal for a one-year ban.[5]

American swimmer Jessica Hardy tested positive at the U.S. trials in July 2008. She served a one-year suspension, having claimed she unknowingly took the drug in a contaminated food supplement. Former New York Mets clubhouse employee Kirk Radomski admitted to distributing clenbuterol to dozens of current and former Major League Baseball players and associates in his plea deal.[6]

Polish sprint canoer Adam Seroczyński was disqualified for taking this drug after he finished fourth in the K-2 1000 m event at the 2008 Summer Olympics in Beijing, and Chinese cyclist Li Fuyu tested positive for it at the Dwars door Vlaanderen race in Belgium on March 24, 2010.[7]

In September 2010, St. Louis Cardinals minor league shortstop Lainer Bueno received a 50-game suspension for the 2011 season as a result of testing positive for clenbuterol.[8]

In June 2011, Mexican National team in soccer were found with this drug but were aquitted by WADA, they claimed that it was contaminated in their food. FIFA have also claimed that 109 players from the Under 17 World Cup in Mexico tested positive for this drug. Claiming that Mexican meat is contaminated.

Contraindications and cautions


Excessive usage over the recommended dose of about 120 μg can cause muscle tremor, headache, dizziness and gastric irritation. Persons self-administering the drug for weight loss or to improve athletic performance have experienced nausea, vomiting, diaphoresis, palpitations, tachycardia and myocardial infarction. Use of the drug may be confirmed by detecting its presence in semen or urine.[9]

Food contamination

In September 2006 over 330 people in Shanghai were reported to have been poisoned by eating pork contaminated by clenbuterol that had been fed to the animals to keep their meat lean.[10]

In February 2009, at least 70 people in one Chinese province (Guangdong) suffered food poisoning after eating pig organs believed to contain clenbuterol residue. The victims complained of stomach aches and diarrhea after eating pig organs bought in local markets.[11][12]

In March 2011, China's Ministry of Agriculture (MOA) said that the government would launch a one-year crackdown on illegal additives in pig feed, after a subsidiary of Shuanghui Group, China's largest meat producer, was exposed for using clenbuterol-contaminated pork in its meat products. A total of 72 people in central Henan Province, where Shuanghui is based, were taken into police custody for allegedly producing, selling or using clenbuterol.[13][14]

Veterinary use

The United States and the European Union prohibit the use of clenbuterol in food-producing animals. It is, however, used in other parts of the world for the treatment of allergic respiratory disease in horses, as it is a bronchodilator. A common trade name is Ventipulmin. It can be used both orally and intravenously. It is also used in cattle to relax the uterus in cows, usually at the time of parturition.[15] It is also a nonsteroidal anabolic and metabolism accelerator,[citation needed] through a mechanism not well understood. Its ability to increase the muscle-to-fat body ratio makes its illegal use in livestock popular to obtain leaner meats.


  1. ^ a b "Clenbuterol", Daily Mail, 2009-10-01,, retrieved 2010-04-07 
  2. ^ Guest, Katy (2007-04-10). "Clenbuterol: The new weight-loss wonder drug gripping Planet Zero". The Independent (London). Retrieved 2007-04-10. 
  3. ^ FDA's Prohibited Drug List, Food Animal Residue Avoidance & Depletion Program
  4. ^ Macur, Juliet (29 September 2010). "With Positive Test, Contador May Lose Tour Title". The New York Times. Retrieved 29 September 2010. 
  5. ^ Brendan Gallagher, Alberto Contador has one-year ban for positive clenbuterol test overturned by Spanish National Cycling Federation,, 15 February 2011
  6. ^
  7. ^ Radioshack suspends Li after doping positive
  8. ^ "Three Minor League players suspended". September 30, 2010. 
  9. ^ R. Baselt, Disposition of Toxic Drugs and Chemicals in Man, 8th edition, Biomedical Publications, Foster City, CA, 2008, pp. 325–326.
  10. ^ "Pigs fed on bodybuilder steroids cause food poisoning in Shanghai" (in English). AFP. 2006-09-19. Retrieved 2006-09-19. 
  11. ^ "China: 70 ill from tainted pig organs –". CNN. 2009-02-23. Retrieved 2010-04-30. 
  12. ^
  13. ^ "China to launch one-year crackdown on contaminated pig feed –". Xinhua. 2011-03-28. Retrieved 2011-03-29. 
  14. ^
  15. ^

External links

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Clenbuterol — Énantiomère S du clenbuterol (en haut) et R clenbuterol (en bas) Général Nom IUPAC …   Wikipédia en Français

  • clenbuterol — /klen būˈtə rol/ noun A drug used in the treatment of asthma, sometimes used illegally to enhance sporting performance …   Useful english dictionary

  • Clenbuterol — Strukturformel (R) Clenbuterol (oben) und (S) Clenbuterol (unten) Allgemeines …   Deutsch Wikipedia

  • clenbuterol — noun The decongestant and bronchodilator 1 (4 amino 3,5 dichloro phenyl) 2 (tert butylamino)ethanol …   Wiktionary

  • Clenbuterol — Clen|bu|te|rol 〈n. 11; unz.; Pharm.〉 entkrampfend wirkender Stoff, der in einigen Asthma u. Hustenmitteln medizinisch eingesetzt wird, gelegentlich als Anabolikum missbraucht, sowohl bei der Kälbermast als auch zur Leistungssteigerung im… …   Universal-Lexikon

  • Clenbuterol® — Clen|bu|te|rol®, das; s [Kunstwort; das Suffix ol bezeichnet in der chem. Fachspr. bestimmte Kohlenwasserstoffe (zu lat. oleum = Öl)]: zur Kälbermast sowie als Dopingmittel verwendetes Anabolikum …   Universal-Lexikon

  • Clenbuterol ® — Clen|bu|te|rol ®, das; s [Kunstwort; das Suffix ol bezeichnet in der chem. Fachspr. bestimmte Kohlenwasserstoffverbindungen (zu lat. oleum = Öl)]: zur Kälbermast sowie als Dopingmittel verwendetes Anabolikum: In einem bei Abduschaparow… …   Universal-Lexikon

  • clenbuterol — clen·bu·ter·ol (klen buґtər ol) a long acting β2 adrenergic agonist used to treat bronchospasms in the horse …   Medical dictionary

  • Clenbuterol — Clen|bu|te|rol 〈n.; Gen.: s; Pl.: unz.; Pharm.〉 entkrampfend wirkender Stoff, der in einigen Asthma u. Hustenmitteln medizinisch eingesetzt wird (gelegentlich gesetzeswidrig als Anabolikum zur Leistungssteigerung im Spitzensport u. bei der… …   Lexikalische Deutsches Wörterbuch

  • Clenbuterol — Clen|bu|te|rol [k...] das; s Kunstw.> ein früher zur Kälbermast u. zum Doping verwendetes Mittel mit ↑anaboler Wirkung …   Das große Fremdwörterbuch

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