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 Clenbuterol (top), and (R)-(−)-clenbuterol (bottom) | |
| Clinical data | |
|---|---|
| Trade names | Dilaterol, Spiropent, Ventipulmin, others[1] |
| AHFS/Drugs.com | International Drug Names |
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| Routes of administration | By mouth |
| Drug class | β2-adrenergic receptor agonist |
| ATC code | |
| Legal status | |
| Legal status | |
| Pharmacokinetic data | |
| Bioavailability | 89–98% (orally) |
| Metabolism | Hepatic (negligible) |
| Eliminationhalf-life | 36–48 hours |
| Excretion | Feces and urine |
| Identifiers | |
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| CAS Number | |
| PubChemCID | |
| IUPHAR/BPS | |
| DrugBank |
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| ChemSpider |
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| UNII | |
| KEGG |
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| ChEBI | |
| ChEMBL | |
| CompTox Dashboard(EPA) | |
| ECHA InfoCard | 100.048.499 |
| Chemical and physical data | |
| Formula | C12H18Cl2N2O |
| Molar mass | 277.19 g·mol−1 |
| 3D model (JSmol) | |
| Chirality | Racemic mixture |
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| (verify) | |
Clenbuterol is asympathomimeticamine used by sufferers of breathing disorders as adecongestant andbronchodilator. People with chronic breathing disorders such asasthma use this as abronchodilator to make breathing easier. It is most commonly available as thehydrochloridesalt, clenbuterol hydrochloride.[2]
It was patented in 1967 and came into medical use in 1977.[3]
Clenbuterol is approved for use in some countries as a bronchodilator for asthma.[medical citation needed]
Clenbuterol is aβ2 agonist with some structural and pharmacological similarities toepinephrine andsalbutamol (albuterol), but its effects are more potent and longer-lasting as a stimulant andthermogenic drug.[citation needed] It is commonly used forsmooth muscle-relaxant properties as a bronchodilator andtocolytic.
It is classified by theWorld Anti-Doping Agency as ananabolic agent, not as a β2 agonist.[4]
Clenbuterol can cause these side effects:[5]
Use over the recommended dose of about 120 μg can cause muscle tremors, 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.[6]
Clenbuterol acts as aβ2-adrenergic receptoragonist.[medical citation needed]
Clenbuterol is not an ingredient of any therapeutic drug approved by the USFood and Drug Administration (FDA)[citation needed] and is now banned forIOC-tested athletes.[7] In the US, administration of clenbuterol to any animal that could be used as food for human consumption is banned by the FDA.[8][9]
Although often used bybodybuilders during their "cutting" cycles,[10] the drug has been more recently[as of?] known to the mainstream, particularly through publicized stories of use by celebrities such asVictoria Beckham,[7]Britney Spears, andLindsay Lohan,[11] for itsoff-label use as a weight-loss drug similar to usage of other sympathomimetic amines such asephedrine, despite the lack of sufficient clinical testing either supporting or negating such use.In 2021, Odalis Santos Mena, a Mexican fitness influencer, died after suffering a cardiac arrest while being anesthetized for a procedure ofmiraDry, a treatment that uses thermal energy to eliminate underarm sweat glands. The coroner reported that Mena's death was attributed to a combination of clenbuterol and anesthesia.
A common misconception about clenbuterol is that it hasanabolic properties, and can increase muscle mass when used in higher dosages. This claim has never been substantiated, and likely originated from equine research.[12] A β2 agonist, Clenbuterol has been found to increase short-term work rate andcardiovascular output, and consequently, its anabolic effects in horses can be attributed to exercise output and increased caloric intake. Given its ability to increasebasal metabolic rate,maximum heart rate, and exercise output, Clenbuterol hasergogenic properties more closely related toephedrine oramphetamine.
The notion that Clenbuterol is an anabolic agent likely originated from author and renowned authority on performance-enhancementDan Duchaine. Duchaine popularized the drug in the bodybuilding community, and was the first to suggest the drug had muscle-building properties. Likewise, Duchaine erred in promoting the drugGamma-hydroxybutyric acid (GHB) as an anabolic agent, and served time for the unlawful possession and distribution of the drug in the mid-1990s.[13]As of 2011, theWorld Anti-Doping Agency (WADA) listed clenbuterol as an anabolic agent, despite the fact there is no evidence to suggest this is the case.[14]
Clenbuterol has also been used as aperformance-enhancing drug. One issue is that clenbuterol is a food contaminant in some countries; doping control must distinguish between accidental and deliberate intake.[15][16]
Clenbuterol is occasionally referred to as "bute" and this risks confusion withphenylbutazone, also called "bute". Phenylbutazone, which is a drug also used with horses, was tested for in the2013 European meat adulteration scandal.[17]
Intended to result in leaner meat with a higher muscle-to-fat ratio, the use of clenbuterol has been banned in meat since 1991 in the US and since 1996 in the European Union. The drug is banned due to health concerns about symptoms noted in consumers. These include increased heart rate, muscular tremors, headaches, nausea, fever, and chills. In several cases in Europe, these adverse symptoms have been temporary.[18]
Clenbuterol is a growth-promoting drug in theβ agonist class of compounds. It is not licensed for use in China,[19] the United States,[18] or the EU[20] for food-producing animals, but some countries have approved it for animals not used for food, and a few countries have approved it for therapeutic uses in food-producing animals.
Not just athletes are affected by contamination. In Portugal, 50 people were reported as affected by clenbuterol in liver and pork between 1998 and 2002, while in 1990, veal liver was suspected of causing clenbuterol poisoning in 22 people in France and 135 people in Spain.[21]
In September 2006, some 330 people inShanghai suffered fromfood poisoning after eating clenbuterol-contaminatedpork.[22]
In February 2009, at least 70 people in oneChinese 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.[23]
In March 2011,China's Ministry of Agriculture said the government would launch a one-year crackdown on illegal additives in pig feed, after a subsidiary ofShuanghui 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.[24] The situation has dramatically improved in China since September 2011, when a ban of clenbuterol was announced by China's Ministry of Agriculture.[25]
Authorities around the world appear to be issuing stricter food safety requirements, such as theFood Safety Modernization Act in the United States, Canada's revision of their import regulations, China's new food laws published since 2009, South Africa's new food law, and many more global changes and restrictions.
Clenbuterol is administered as an aerosol for the treatment ofallergic respiratory disease in horses as abronchodilator, and intravenously in cattle to relax the uterus in cows at the time ofparturition,[26] specifically to facilitate exteriorisation of the uterus during Caesarian section surgery. It is licensed for obstetrical use in cattle as Planipart Solution for Injection.[27]
It is illegal in some countries to use in livestock used for food.[28]
