Albuterol
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Salbutamol
Systematic (IUPAC) name
4-[2-(tert-butylamino)-1-hydroxyethyl]-2-(hydroxymethyl)phenol
Identifiers
CAS number	18559-94-9
ATC code	R03AC02 R03CC02
PubChem	2083
DrugBank	APRD00553
Chemical data
Formula	C13H21NO3
Mol. mass	239.311
SMILES	eMolecules & PubChem
Pharmacokinetic data
Bioavailability	?
Metabolism	Hepatic
Half life	1.6 hours
Excretion	Renal
Therapeutic considerations
Pregnancy cat.	A(AU) C(US)
Legal status	Pharmacist Only (S3)(AU) ?(CA) POM(UK) ℞-only(US)
Routes	Oral, inhalational, IV

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.

Salbutamol sulfate is usually given by the inhaled route for direct effect on bronchial smooth muscle. This is usually achieved through a metered dose inhaler (MDI), nebuliser or other proprietary delivery devices (e.g. Rotahaler or Autohaler). In these forms of delivery, the maximal effect of Salbutamol can take place within five to twenty minutes of dosing, though some relief is immediately seen. Salbutamol can also be given orally as an inhalant or intravenously. However, some asthmatics may not respond to these medications as they will not have the required DNA base sequence in a specific gene.

Salbutamol became available in the United Kingdom in 1969 and in the United States in 1980 under the trade name Ventolin.

Clinical use

Salbutamol is specifically indicated in the following conditions:

• acute asthma
• symptom relief during maintenance therapy of asthma and other conditions with reversible airways obstruction (including COPD)
• protection against exercise-induced asthma
• hyperkalaemia, especially in patients with renal failure
• can be aerosolized with a nebulizer for patients with cystic fibrosis, along with ipratropium bromide and pulmozyme.

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 labour. Whilst preferred over agents such as atosiban and ritodrine, its role has largely been replaced by the calcium-channel blocker nifedipine which is more effective, better tolerated and orally administered.^[1]

Diet and bodybuilding use

Salbutamol is taken by some as an alternative to Clenbuterol for purposes of fat burning.^[2]

In numerous animal studies it has been shown that heart damage has occurred in animals given doses of clenbuterol over extended periods of time. With albuterol, no such damage has ever been demonstrated. This may be due to the length of time that a user is exposed to the drug and therefore the likelihood that damage could occur. Many online bodybuilding and sculpting related websites address these issues and the positive and negative effects on humans, most of which show extensive positive results with little to no side effects unlike clenbuterol.^{citation needed}

Dosage recommendations vary between most users, given that use of salbutamol for this purpose is considered abuse by most pharmacologists and doctors little to no actual scientific or medical data is available. Doses generally start in the range of 2mg per day, escalating to a maximum of 16mg per day or where side effects are noticed.^{citation needed}

Mode of action

As with other β₂-adrenergic receptor agonists, salbutamol binds to β₂-adrenergic receptors with a higher affinity than β₁-receptors. In the airway, activation of β₂-receptors results in relaxation of bronchial smooth muscle resulting in a widening of the airway (bronchodilation). Inhaled salbutamol sulfate has a rapid onset of action, providing relief within five to fifteen minutes of administration.

In tocolysis, the activation of β₂-receptors results in relaxation of uterine smooth muscle, thus delaying labour.

Adverse effects

While salbutamol is well-tolerated, particularly when compared with previous therapies such as theophylline, like all medications there exists the potential for adverse drug reactions to occur - especially when in high doses, or when taken orally or intravenously.

Serious side effects

• bronchospasm (wheezing, chest tightness, trouble breathing), especially after starting a new canister of this medicine;
• chest pain and fast, pounding, or uneven heart beats, palpitations;
• tremor, nervousness; or
• low blood pressure (Rossi, 2004)
• dangerously high blood pressure (severe headache, blurred vision, buzzing in your ears, anxiety, confusion, chest pain, shortness of breath, uneven heartbeats, seizure) ^{[3] [4]}

Less serious side effects

• urticaria
• angioedema
• headache, dizziness, nervousness;
• sleep problems (insomnia);
• cough, hoarseness, sore throat, runny or stuffy nose;
• dry mouth and throat;
• muscle pain; or muscle cramps
• hypokalemia, tinnitus, hyperactivity in children
• hyperglycemia, lactic acidosis
• otitis media, vertigo ^[5]
• anaphylaxis, diaphoresis, lymphadenopathy
• diarrhea ^[4][3][5](Rossi, 2004)

Salbutamol is usually sold in racemic form. The (S) enantiomer of salbutamol has little activity as a β₂-adrenergic receptor agonist, and can inhibit the anti-inflammatory effect of steroids prescribed to treat asthma. However, the (R) enantiomer can stimulate the steroid's effect. The overall combined effect of the two isomers is unclear.

Brand names

Salbutamol is sold under the brand names Aerolin, Airomir, Apo-salvent Asmasal, Asthalin, Asthavent, Asmol, Butahale,Buventol, ProAir, Proventil, Salamol, Sultanol, Ventolin, Ventorlin and Volmax.

Levalbuterol, the R-enantiomer of salbutamol, is sold as Xopenex.

U.S. Brand Names

• AccuNeb®
• ProAir™ HFA
• Proventil® HFA
• Proventil®
• Ventolin® HFA
• VoSpire ER®

Canadian Brand Names

• Airomir
• Alti-Salbutamol
• Apo-Salvent® CFC Free
• Apo-Salvent® Respirator Solution
• Apo-Salvent® Sterules
• Apo-Salvent®
• Gen-Salbutamol
• PMS-Salbutamol
• ratio-Inspra-Sal
• ratio-Salbutamol
• Rhoxal-salbutamol
• Salbu-2
• Salbu-4
• Ventolin® Diskus
• Ventolin® HFA
• Ventolin® I.V. Infusion
• Ventolin®
• Ventrodisk ^[5]

Ban of CFC-containing albuterol inhalers

The U.S. Food & Drug Administration in April of 2005 mandated that all (including albuterol) inhalers containing chlorofluorocarbons (CFCs) will be prohibited in the United States as of 12/31/2008. CFC inhalers had previously been given "essential use" status, exempting it from a CFC-production ban, however in accordance with the Montreal Protocol they will be phased out; in many other countries patients have been transitioned to non-CFC based (HFA) inhalers. Pharmaceutical manufacturers are expected to produce adequate supplies of alternative (HFA) inhalers by 2009.

One drawback of this transition to HFA inhalers is that due to patent restrictions all of the HFA albuterol inhalers are "brand-name" (ProAir, Proventil, and Ventolin). They cost approximately $20 more per inhaler than existing generic CFC albuterol inhalers. Generic HFA albuterol inhalers are not expected on the market until 2017 due to existing patents, although some pharmaceutical companies will offer discounts for those who cannot afford the HFA inhalers.

Benefits of transitioning to HFA inhalers include (1) increased drug deposition in the distal airways, (2) more consistent drug delivery from nearly empty canisters, and (3) more consistent drug delivery at a greater range of canister temperatures. It should be noted that the spray force of HFA inhalers is less than that of CFC inhalers, which may mislead some patients to believe that they may not be receiving enough albuterol when in fact they are seeing the benefits as outlined above.

References

1. Anabolic effects of the beta 2-adrenoceptor agonist salmeterol are dependent on route of administration N. G. Moore, G. G. Pegg, and M. N. Sillence Am J Physiol Endocrinol Metab, Sep 1994; 267: E475 - E484.
2. Schiffelers SL, Saris WH, Boomsma F, and van Baak MA. beta(1)- and beta(2)-Adrenoceptor-mediated thermogenesis and lipid utilization in obese and lean men. J Clin Endocrinol Metab 86: 2191-2199, 2001
3. Effect of salbutamol on muscle strength and endurance performance in nonasthmatic men. Med Sci Sports Exerc. 2000 Jul;32(7):1300-6. J Strength Cond Res. 2005 Feb;19(1):102-7. Oral Albuterol dosing during the latter stages of a resistance exercise program
4. The effects of Albuterol and isokinetic exercise on the quadriceps muscle group.Med Sci Sports Exerc. 1995 Nov;27(11):1471-6
5. Salbutamol, a beta 2-adrenoceptor agonist, increases skeletal muscle strength in young men.Martineau L, Horan MA, Rothwell NJ, Little RA
6. Different Ability of Clenbuterol and Salbutamol to Block Sodium Channels Predicts Their Therapeutic Use in Muscle Excitability Disorders Jean-François Desaphy, Sabata Pierno, Annamaria De Luca, Paola Didonna, and Diana Conte Camerino Mol. Pharmacol., Mar 2003; 63: 659
7. Metabolism. 1996 Jun;45(6):712-7 Effects of oral albuterol on serum lipids and carbohydrate metabolism in healthy men. Maki KC, Skorodin MS, Jessen JH, Laghi F

See also

Carter Vanderbilt Cooper

External links

• Albuterol
• Volmax Drug Information