Salbutamol (top) and (S)-salbutamol (bottom)
|Systematic (IUPAC) name|
|Licence data||US FDA:|
|Oral, inhalational, IV|
|Biological half-life||3.8 - 6 hours|
|ATC code||R03 R03|
|Molecular mass||239.311 g/mol|
|(what is this?)|
Salbutamol (INN) or albuterol (USAN) is a short-acting β2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease (COPD). It is marketed as Ventolin among other brand names.
Salbutamol was the first selective β2-receptor agonist to be marketed in 1968. It was first sold by Allen & Hanburys (UK) under the brand name Ventolin, and has been used for the treatment of asthma ever since. It was approved for use in the US by the Food and Drug Administration (FDA) in May 1982.
Salbutamol is mostly taken by the inhaled route for direct effect on bronchial smooth muscle. This is usually achieved through a metered-dose inhaler (MDI), nebulizer, or other proprietary delivery devices. In these forms of delivery, the maximal effect of salbutamol can take place within five to 20 minutes of dosing, though some relief is immediately seen. Mean duration of effect is roughly 2 hours. It can also be given intravenously. Salbutamol is also available in oral form (tablets, syrup).
It is on the World Health Organization's List of Essential Medicines, a list of the most important medication needed in a basic health system. Compliance with the Montreal Protocol, which requires the banning of the use of ozone-layer depleting CFCs, has caused the price of inhalers, however, to increase as much as ten-fold as generics were forced off the market from 2009 to 2013 by new patents obtained by pharmaceutical companies for non-CFC delivery systems.
Salbutamol is typically used to treat bronchospasm (due to any cause, allergen asthma or exercise-induced), as well as chronic obstructive pulmonary disease. Emergency medical practice commonly treats people presenting with asthma who report taking their salbutamol inhaler as prescribed with salbutamol; in general, people tolerate large doses well.[clarification needed]
As a β2-agonist, salbutamol also finds use in obstetrics. Intravenous salbutamol can be used as a tocolytic to relax the uterine smooth muscle to delay premature labor. While preferred over agents such as atosiban and ritodrine, its role has largely been replaced by the calcium-channel blocker nifedipine, which is more effective, better tolerated and orally administered.
Salbutamol has also been tested in a trial aimed at treatment of spinal muscular atrophy, where it appears to show modest benefits. The drug is speculated to modulate the alternative splicing of the SMN2 gene, increasing the amount of the SMN protein whose deficiency is regarded as the root cause of the disease.
The most common side effects are fine tremor, anxiety, headache, muscle cramps, dry mouth, and palpitation. Other symptoms may include tachycardia, arrhythmia, flushing, myocardial ischemia (rare), and disturbances of sleep and behaviour. Rarely occurring, but of importance, are allergic reactions of paradoxical bronchospasm, urticaria, angioedema, hypotension, and collapse. High doses or prolonged use may cause hypokalaemia, which is of concern especially in patients with renal failure and those on certain diuretics and xanthine derivatives.
Structure and activity
This drug is sold as a racemic mixture. The (R)-enantiomer (CIP nomenclature) is shown in the image at right (top), and is responsible for the pharmacologic activity; the (S)-enantiomer (bottom) blocks metabolic pathways associated with elimination both of it and of the pharmacologically active enantiomer.
Detection after dosing
Salbutamol may be quantified in blood or plasma; practical needs for this include to confirm a diagnosis of poisoning in hospitalized patients, or to aid in a forensic investigation. As well, urinary salbutamol concentrations are frequently measured in competitive sports programs, for which a level in excess of 1000 μg/L is considered to represent abuse.
The window of detection for urine testing is on the order of just 24 hours, given the relatively short elimination half-life of the drug, estimated at between 5 and 6 hours following oral administration of 4 mg.
Society and culture
||This section needs more medical references for verification or relies too heavily on primary sources. (October 2015)|
Salbutamol has been shown to improve muscle weight in rats  and anecdotal reports hypothesise that it might be an alternative to clenbuterol for purposes of fat burning and muscle gain, with multiple studies supporting this claim. Abuse of the drug may be confirmed by detection of its presence in plasma or urine, typically exceeding 1000 µg/L.
Clinical studies show no compelling evidence that salbutamol and other β2-agonists can increase performance in healthy athletes. In spite of this, salbutamol required "a declaration of Use in accordance with the International Standard for Therapeutic Use Exemptions" under the 2010 WADA prohibited list. This requirement was relaxed when the 2011 list was published to permit the use of "salbutamol (maximum 1600 micrograms over 24 hours) and salmeterol when taken by inhalation in accordance with the manufacturers’ recommended therapeutic regimen." 
Another study contradicts the above findings, however. The double blind, randomised test conducted on 12 non-asthmatic athletes concluded that salbutamol had a negligible effect on endurance performance. Nevertheless, the study also showed that the drug's bronchodilating effect may have improved respiratory adaptation at the beginning of exercise.
|This section requires expansion with: further updated information, and statement of the date through which the information is up-to-date. (May 2015)|
|This section does not cite any references (sources). (May 2015)|
Drug forms of this compound are marketed by GlaxoSmithKline as Ventolin, Ventoline, Ventilan, Aerolin, or Ventorlin, depending on the market; by Cipla as Asthalin and Asthavent; by Schering-Plough as Proventil, by Remedica as Salbutamol 4,by Teva as ProAir and Novo-Salbutamol HFA (Canada), Salamol, or Airomir, by Beximco (Bangladesh) as Azmasol by Ad-din Pharma as Ventosol and by Alphapharm as Asmol.
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- Salbutamol at The Periodic Table of Videos (University of Nottingham)
- Volmax Drug Information
- Side Effects
- U.S. National Library of Medicine: Drug Information Portal – Albuterol