Salbutamol

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Salbutamol
Systematic (IUPAC) name
2-(hydroxymethyl)-4-[1-hydroxy- 2-(tert-butylamino)ethyl]phenol
Identifiers
CAS number	18559-94-9
ATC code	R03 AC02 R03 CC02
PubChem	2083
DrugBank	APRD00553
Chemical data
Formula	C₁₃H₂₁N O₃
Mol. weight	239.311
Pharmacokinetic data
Bioavailability	?
Metabolism	Hepatic
Half life	1.6 hours
Excretion	Urinary
Therapeutic considerations
Pregnancy cat.	A(AU) C(US)
Legal status	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 COPD.

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). Salbutamol can also be given orally 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.

1 Clinical use
2 Mode of action
3 Adverse effects
4 Other brand names
5 References
6 External links

[edit] 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
hyperkalemia, especially in patients with renal failure
can be aerosolized 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 Whilst preferred over agents such as atosiban and ritodrine, its role has largely been replaced by the calcium-channel blocker nifedipine which is more effective, better tolerated and orally administered.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]

[edit] 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 5-15 minutes of administration.

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

[edit] 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.

Common adverse effects include: tremor, palpitations and headache. (Rossi, 2004)

Infrequent adverse effects include: tachycardia, muscle cramps, agitation, hypokalemia, hyperactivity in children, and insomnia. ^[1]

The (S) isomer of salbutamol can inhibit the anti-inflammatory effect of steroids prescribed to treat asthma. However, the (R) isomer stimulates the steroid's effect and the overall effect of the two isomers is unclear^[2].

[edit] Other brand names

Salbutamol is sold under the brand names Airomir, Asthalin, Asmol, Buventol, Proventil, Salamol, Sultanol, Ventolin and Volmax.

[edit] References

^ ^a ^b Rossi S (Ed.) (2004). Australian Medicines Handbook 2004 (AMH). Adelaide: Australian Medicines Handbook. ISBN 0-9578521-4-2.
^ A BBC Scare Story by Blacktriangle.

[edit] External links

Volmax Drug Information (drugs.com)
Links to external chemical sources.

Medications commonly used in asthma and COPD (primarily R03) edit
Anticholinergics:	Ipratropium, Tiotropium
Short acting β₂-agonists:	Salbutamol, Terbutaline
Long acting β₂-agonists (LABA):	Clenbuterol, Formoterol, Salmeterol
Corticosteroids:	Beclometasone, Budesonide, Fluticasone
Leukotriene antagonists:	Montelukast, Pranlukast, Zafirlukast
Xanthines:	Aminophylline, Theobromine, Theophylline
Mast cell stabilizers:	Cromoglicate, Nedocromil
Combination products:	Budesonide/formoterol, Fluticasone/salmeterol, Ipratropium/salbutamol