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Clenbuterol ball-and-stick model.png
and (R)-(−)-clenbuterol (bottom)
AHFS/Drugs.com International Drug Names
administration Oral (tablets, oral solution)
ATC code R03AC14 (WHO) R03CC13 (WHO) QG02CA91 (WHO)
UK: POM (Prescription only)
Bioavailability 89–98% (orally)
Metabolism Hepatic (negligible)
Biological half-life 36–48 hours
Excretion Feces and urine
CAS Number 37148-27-9 Yes
PubChem (CID) 2783
DrugBank DB01407 Yes
ChemSpider 2681 Yes
UNII XTZ6AXU7KN Yes
KEGG D07713 Yes
ChEBI CHEBI:174690 Yes
ChEMBL CHEMBL49080 Yes
ECHA InfoCard 100.048.499
Chemical and physical data
Molar mass 277.19
3D model (Jmol) Interactive image
Chirality Racemic mixture
Clenbuterol, marketed as Dilaterol, 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.
1 Effects and dosage
2 Human use
2.1 Legal status
2.2 Weight-loss drug
2.3 Notable cases of use as performance-enhancing drug
2.4 Side effects and dangers
2.6 Food contamination
3 Veterinary use
4 See also
6 External links
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, blood pressure, and oxygen transportation. It increases the rate at which body fat is metabolized while increasing the body’s basal metabolic rate (BMR). It is commonly used for smooth muscle-relaxant properties as a bronchodilator and tocolytic.
Clenbuterol is also prescribed for treatment of horses, but equine use is usually the liquid form.
Clenbuterol is approved for use in some countries, free or via prescription, as a bronchodilator for asthma patients.
Clenbuterol is not an ingredient of any therapeutic drug approved by the US Food and Drug Administration and is now banned for IOC-tested athletes. In the US, administration of clenbuterol to any animal that could be used as food for human consumption is banned by the FDA.
Although often used by bodybuilders during their “cutting” cycles, the drug has been more recently known to the mainstream, particularly through publicized stories of use by celebrities such as Victoria Beckham, Britney Spears, and Lindsay Lohan,  for its off-label use as a weight-loss drug similar to usage of other sympathomimetic amines such as ephedrine, despite the lack of sufficient clinical testing either supporting or negating such use.